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Small Price Changes, Sales Volume, and Menu Cost*
Doron Sayag
Department of Economics, Bar-Ilan University
Ramat-Gan 5290002, Israel
Doronsayag2@gmail.com
Avichai Snir
Department of Economics, Bar-Ilan University
Ramat-Gan 5290002, Israel
Snirav@biu.ac.il
Daniel Levy**
Department of Economics, Bar-Ilan University
Ramat-Gan 5290002, Israel,
Department of Economics, Emory University
Atlanta, GA 30322, USA,
ICEA, ISET at TSU, and RCEA
Daniel.Levy@biu.ac.il
Revised: February 29, 2024
Keywords: Menu cost, (S, s) band, price rigidity, sticky prices, small price changes, small
price adjustments, sales volume
JEL Codes: E31, E32, L16, L81, M31
* This is a substantially revised version of the manuscript that was presented at the 2021 ECB-Federal Reserve Bank of
Cleveland Conference on Inflation: Drivers and Dynamics, at the 2021 ICEA’s 3rd Warsaw Money-Macro-Finance
Conference, at the 2022 annual conference of the Royal Economic Society, at the 2022 annual conference of the
Armenian Economic Association, at the 2023 annual conference of the Israeli Economic Association, at the 2023
International Conference on Empirical Economics at Pennsylvania State University, and at the Bank of Israel Research
Seminar. We thank the participants of these conferences for their helpful and constructive comments and suggestions.
All errors are ours.
Declarations of interest: None
** Corresponding author: Daniel Levy, Daniel.Levy@biu.ac.il
Small Price Changes, Sales Volume, and Menu Cost
Abstract
The finding of small price changes in many retail price datasets is often viewed as a puzzle.
We show that a possible explanation for the presence of small price changes is related to
sales volume, an observation that has been overlooked in the existing literature. Analyzing
a large retail scanner price dataset that contains information on both prices and sales
volume, we find that small price changes are more frequent when products’ sales volume
is high. This finding holds across product categories, within product categories, and for
individual products. It is also robust to various sensitivity analyses such as measurement
errors, the definition of “small” price changes, the inclusion of measures of price
synchronization, the size of producers, the time horizon used to compute the average sales
volume, the revenues, the competition, shoppers’ characteristics, etc.
1
1. Introduction
Extensive empirical analyses of price-setting behavior using various micro-level price
datasets show that individual prices tend to change at a significantly lower frequency than
the corresponding market conditions.
1
A leading model offered to explain the sluggish
response of prices to underlying shocks is the menu cost model, which posits that each
time a firm changes a price, it incurs a lump sum cost that is independent of the size or
the direction of the price change.
2
A key prediction of the simple menu cost model is that firms make infrequent but
relatively large price changes because making frequent small price changes is less
economical (Caplin and Spulber 1987). However, empirical studies find that 20%–44%
of the observed price changes are small, which many authors see as evidence against the
simple menu cost model.
3
To reconcile the existence of small price changes with menu costs, Dotsey et al.
(1999) model stochastic menu costs, which lead to small price changes when the realized
menu cost is small. Lach and Tsiddon (2007), Klenow and Malin (2011), Midrigan
(2011), Alvarez and Lippi (2014) and Alvarez et al. (2016) suggest economies of scope in
price adjustments, allowing both small and large price changes, as long as the average
price change is larger than the menu cost.
4
Chakraborty et al. (2015), Rotemberg (1982),
and Chen et al. (2008) suggest that consumer inattention can explain small price changes.
In this paper, which is primarily empirical, we use a large scanner retail price dataset
with over 98 million weekly observations to show that sales volumes can be another
explanation for small price changes. The empirical evidence we present suggests that
small price changes are significantly more likely for products with high sales volumes
than for products with low sales volumes. This result is robust. It holds across product
categories, within product categories, or at the level of individual products across stores.
1
Examples include Carlton (1986), Cecchetti (1986), Lach and Tsiddon (1992, 1996, 2007), Kashyap (1995), Blinder
et al. (1998), Slade (1998), Eden (2001, 2018), Dutta et al. (1999, 2002), Fisher and Konieczny (2000, 2006), Owen
and Trzepacz (2002), Chevalier et al. (2003), Baharad and Eden (2004), Bils and Klenow (2004), Levy and Young
(2004), Zbaracki et al. (2004), Álvarez et al. (2006), Dhyne et al. (2006), Knotek (2008, and forthcoming), Nakamura
and Steinsson (2008), Campbell and Eden (2014), Kehoe and Midrigan (2015), Konieczny and Skrzypacz (2005,
2015), Gorodnichenko and Talavera (2017), Anderson et al. (2015, 2017), and studies cited therein. For older surveys,
see Romer (1993), Weiss (1993), Taylor (1999), Willis (2003), and Wolman (2007). More recent surveys include
Klenow and Malin (2011), Leahy (2011), and Nakamura and Steinsson (2013).
2
See, for example, Barro (1972), Sheshinski and Weiss (1977 and 1992), Akerlof and Yellen (1985), Mankiw (1985),
and Konieczny and Rumler (2006).
3
See, for example, Bils and Klenow (2004), Nakamura and Steinsson (2008), Chen et al. (2008), Klenow and Kryvtsov
(2008), Msidrigan (2011), Bhattarai and Schoenle (2014), Klenow and Malin (2011), and Gautier et al. (forthcoming).
4
Alvarez et al. (2014), Eichenbaum et al. (2014), Cavallo and Rigobon (2016), and Cavallo (2018) suggest that many
of the reported small price changes are due to measurement errors. Even these studies, however, find a non-negligible
share of small price changes that cannot be explained by measurement errors.
2
It is also robust to various sensitivity analyses such as the definition of “small” price
changes in relative vs. absolute terms, measurement errors, the time horizon used to
compute the average sales volume, and the inclusion of controls for competition,
markups, pricing zones, producers’ size, etc.
Sales volumes as an explanation for small price changes seem to have been
overlooked by the existing literature, although it has a straightforward intuition. Under a
menu cost (i.e., non-convex lump-sum price adjustment cost), the firm incurs the same
price adjustment cost regardless of the number of units sold because it pays the menu cost
once to change the price of all units sold. If it sells one unit, it will change the price only
if the benefit from the change exceeds the menu cost. If it sells many units, the benefit
from changing the price is accumulated across all units sold, while the menu cost is the
same, which will likely make a small price change more profitable. Thus, comparing
products that differ only in sales volume, we expect that products with higher sales
volumes would have more price changes and that their price changes would be smaller,
on average, than products with lower sales volumes. In the appendix, we show that the
data is consistent with both predictions.
Particularly relevant to our work are Bhattarai and Schoenle (2014) and Kang and
Usher (2023). Bhattarai and Schoenle (2014) use the BLS micro-level price data
underlying the PPI to show that the average size of price changes is negatively correlated
with the number of products offered by a producer. They also present evidence
suggesting that producers that offer many products tend to have high sales volume.
We check if our results may be driven by large firms having higher sales volume or
more price changes. We find that controlling for (a) the number of products offered by
each producer, (b) the percentage of prices that change, and (c) the average size of all
price changes (excluding the current price change), has little effect on the estimated
coefficients of the sales volume.
Kang and Usher (2023) construct a model based on the assumption that the size of
price changes is negatively correlated with the revenue and therefore, small price changes
are possible if the revenue is sufficiently large. Because there is a strong correlation
between sales volume and revenues (in our data, the average correlation is 0.85), our
model and findings are consistent with their model and findings. Indeed, when we test the
correlation between the likelihood of small changes and revenue, we find a positive and
significant correlation. However, our empirical results further suggest that the positive
correlation between revenue and small price changes is driven by the sales volume
3
component of the revenue, and not by the price component.
Our results are likely to hold in other datasets as well. For example, the strong
correlation between sales volume and revenue suggests that our results are likely to hold
in Kang and Usher’s (2023) data. In addition, although the Bhattarai and Schoenle (2014)
data does not allow direct analysis of the correlation between small price changes and
sales volume, the observation that our results hold along with their results, suggests that
such a correlation exists in their data.
Further, our results suggest that a lack of correlation between the price gap and the
likelihood of a price change, as reported by Karadi et al. (forthcoming), for example, is
not necessarily evidence against selection. If the likelihood of a small price change
depends on sales volumes, then retailers might select to adjust prices of products with
high sales volumes even if the deviation of their price from the optimal price is small.
Thus, even when selection is present, in the wake of a monetary shock we are likely to
observe both large and small price changes.
We proceed as follows. To motivate our empirical analyses, in section 2, we extend
Barro’s (1972) model to derive a relationship between the width of the (S, s) band and the
sales volume. In section 3, we discuss the data. In section 4, we present the empirical
findings. In section 5, we discuss robustness. We conclude in section 6.
2. Sales volume and the width of the optimal (S, s) band
To motivate the empirical analyses of the relationship between sales volumes and the
prevalence of small price changes, we extend Barro’s (1972) model. Although the model
is highly stylistic, it is useful because one criticism of the canonical menu cost model is
that it fails to predict small price changes. We show that conditional on sales volume,
even this highly stylistic model can predict small price changes.
Following Barro (1972), consider a profit-maximizing monopolist producing a
homogenous good. The linear demand and the quadratic cost functions are given by
Y P u
and
2
()C Y a bY cY
, respectively, where u is a symmetric demand
disturbance/shifter,
( ) 0CY
, and
, , , , 0abc
. The producer’s maximization problem
is thus given by:
2
max
s.t.
PY a bY cY
Y P u
(1)
Setting
MR MC
, and solving for P and Y, we obtain
4
212
*2 1 2 1
cb c
Pu
cc
(2)
and
1
*2 1 2 1
b
Yu
cc
(3)
The second-order condition for a maximum is given by
10c
.
In the absence of a disturbance, i.e. if
0u
, the profit-maximizing output is given by
0
*21
u
b
Yc
(4)
where
0b
, which is required for the output to be positive in the disturbance-free
equilibrium. We can think of
0
*u
Y
as the expected output.
Following Barro (1972, p. 19), suppose that the value of the disturbance changes from
0 to u. Assuming that the firm continuously adjusts its price and output to the change in
u, the resulting change in the firm’s profit, as Barro shows, is given by
(0, ) 0
0
2
()
1
2 1 4 1
u
u
u
ddu
du
P C Y du
buu
cc
(5)
Next, assume that the firm’s price is sticky, stuck at
ˆ
P
, which denotes the optimal
price in the disturbance-free equilibrium, such that
ˆ0dP du
. Then, (2) implies that
2
ˆ21
cb
Pc
(6)
We follow Barro (1972, p. 20) to assume that the disturbance is not “too small” or “too
large”, i.e.,
min max
u u u
. This is necessary to avoid the situations of no production,
which will be the case if
min
uu
, or a shortage, which will be the case if
max
uu
. Then,
(0, ) 0
0
2
ˆ
ˆ
ˆˆ
()
21
u
u
u
ddu
du
P C Y du
bu cu
c
(7)
The expression in (7) is the change in the profit when the disturbance value changes from
5
0 to u, but the firm does not adjust its price, i.e. when the price is stuck at
ˆ
P
.
The firm’s profit gain, if it adjusts its price to the demand shock, is therefore given by
2
(0, ) (0, )
ˆ
uu
u
(8)
where
2
12 0
41
c
c
(9)
The expression in (8) can be interpreted as the loss the firm incurs for not adjusting its
price in response to the demand shock. As Barro (1972, p. 20) notes, the symmetry of this
loss means that what matters is the size of the demand shock, not its sign. It follows that
the optimal price adjustment rule (S, s), is symmetric. Also, for a given disturbance u, the
loss from not adjusting the price decreases with the price sensitivity of demand
, and
increases with the slope of the marginal cost curve
( ) 2C Y c
.
Barro’s (1972) main conclusion is that if u follows a symmetric random walk, then
the optimal (S, s) band is symmetric, given by
ˆˆ
,hh
, where
0.25
6
ˆ
h
(10)
where
is a fixed, lump-sum menu cost,
2
is the variance of the Bernoulli process
driving the symmetric random walk, and
is given by (9).
5
According to (10), the higher the menu cost, the wider the band of inaction. On the
other hand, a high
implies a narrow band of inaction. That is because according to
(8)–(9), a high
means a greater profit loss from not adjusting the price.
In models with CES demand, the optimal value of the barrier
ˆ
h
is independent of the
output produced, because of the constant price elasticity assumption. Here, however, the
demand is assumed linear and thus its price elasticity is not constant. We can therefore
take advantage of this property by extending the model to derive the relationship between
the optimal barrier, i.e., the optimal (S, s) band, and the output. Rewrite (9) as
2
2
12
41
12
2 1 2
c
c
c
b
cb
(11)
5
The expression for the barrier
ˆ
h
as given above, is identical to the expression for the barrier that Dixit (1991, p. 144)
derives and reports in his equation (11).
6
By (4), the term in the first brackets is the optimal level of output in the disturbance-free
equilibrium
0
*u
Y
. Therefore, (11) can be written as a function of
0
*u
Y
,
2
00
12
**
2
uu
c
YY b
(12)
which shows that
0
*u
Y
, i.e.,
is a function of
0
*u
Y
.
To show the effect of changes in output
0
*u
Y
on the frequency of small price
changes, consider a change in
which by (4) affects the output
0
*u
Y
because of its
effect on the demand, while in parallel it also affects
by (11). Note that from the first
part of (11), it follows that
2
2
2
12
41
12
41
0
c
c
c
c
(13)
while from (10) it follows that
1
4
1
4
5
4
ˆ6
6
4
0
h
(14)
Now consider a situation where there is an increase in demand because of a decrease
in
, which leads to higher
0
*u
Y
because, using (4), we have
2
0
2(1 )
()
2( 1)
0
*ub
c
cb
c
Y
(15)
Then, the decrease in
which by (15) increases
0
*u
Y
, increases
by (13), which by
(14) decreases
ˆ
h
, making the (s, S) band narrower.
Another way to see this, is to find directly the sign of the partial derivative of
ˆ
h
with
7
respect to
, by first substituting (9) in (10). Then we obtain the partial derivative
1
4
ˆ6h
1
4
2
6
12
41
c
c
42 3 2
3
4
2
4 1 1
3
21 2 1 2 1 2
1
212
c c c
c
c c c
c
c
(16)
4
3
4
3
2
3
2
1
2 1 2 12
c
cc
0
The expressions in (13)(15), or alternatively (15)(16), constitute our main
analytical result. Consider, for example, a situation where there is an increase in demand
because of a decrease in
. Then, according to (15), output will increase. But according
to (16), the decrease in
will reduce
ˆ
h
, leading to a narrower optimal (S, s) band. In
other words, there is an inverse relationship between the level of output (as determined
by the demand) and the width of the (S, s) band. If the output of the monopolist is high
(low), then the (S, s) band will be narrower (wider), which means that we will see more
(less) frequent smaller price changes. Trivially, this will be true for small menu costs.
However, our result is independent of the size of the menu cost. That is, the model
predicts that we will likely see small price changes even if the menu cost is large.
Another implication of the reduction in the width of the (S, s) band is that as the sales
volume increases, the frequency of price changes, irrespective of their size, should also
increase. We test this second prediction in Appendix O, in the Online Supplementary
8
Appendix, and find that it is supported by the data.
3. Data
We use data from Dominick’s, a large US retail food chain with 93 stores in the
greater Chicago area with a market share of 25%. The data contain more than 98 million
weekly observations over 8 years, from September 14, 1989, to May 8, 1997, for 13,504
products in 29 categories, including food, cleaning products, hygienic products, and
pharmaceutical products.
6
Each weekly observation includes the retail price, the number
of units sold, the revenue, the retailer's markup, and some product attributes. These
features make Dominick's dataset especially well-suited for our analysis.
An important attribute of Dominick’s data is that its prices were set on a weekly
basis. Thus, each week there was one price. If manufacturer coupons were used, we
cannot account for these. During the sample period, however, the use of such coupons
was limited (Barsky et al. 2003, Chen et al. 2008, Levy et al. 2010 and 2011).
4. Empirical findings
4a. Results of pooled analysis
To study the correlation between sales volumes and small price changes, we follow Chen
et al. (2008) to define a small price change as a price change of 10¢ or less. We choose to
focus on the absolute rather than the relative size of price changes because our hypothesis
implies that a price change of a given size is profitable if the change in cents multiplied
by the sales volume is greater than the menu cost. For example, a change of 1 cent in a
price adds 1 cent to the revenue if the firm sells 1 unit and $10 if the firm sells 1,000
units, irrespective of the price prior to the change. For our purpose, therefore, it makes
sense to define small price changes in cents. In addition, a “unit” in our data may be
composed of multiple units, e.g., a six-pack of beer. In such cases, we count each pack as
a single unit, because the consumer pays once for the entire pack.
In the appendix, we show that our results hold (and are even stronger), if we exclude
multi-units packs. In the appendix, we also show that our findings are robust to
alternative definitions of small price changes, including 5¢, 15¢, 2%, and 5%, as well as
relative to the average product-level price change (Midrigan 2011, and Bhattarai and
Schoenle 2014). Thus, although we focus here on absolute price changes, the results also
6
Dominick’s data contains observations on 18,035 UPCs. However, some of the UPCs are re-launches of the same
product. See Mehrhoff (2018), and Dominick’s Data Manual (p. 9), available at https://www.chicagobooth.edu/-
/media/enterprise/centers/kilts/datasets/dominicks-dataset/dominicks-manual-and-codebook_kiltscenter.aspx.
9
apply to relative price changes, as in Alvarez et al. (2016).
Another possible source of noise in our data is measurement errors (Alvarez et al.,
2016). As Eichenbaum et al. (2014) note, prices reported in scanner datasets are weekly
average prices. This can result in spurious small price changes when shoppers pay
different prices, for example when some shoppers use coupons.
7
To control for this, we
use observations on price changes only if the post-change price lasted for at least two
consecutive weeks. As noted by Strulov-Shlain (2023), the likelihood that a spurious
price change would persist for more than one week is very low. In the appendix, we
report the results of two other robustness tests. In the first, we exclude observations
where price changes are
2¢ (Alvarez et al., 2016). In the second, we exclude
observations where Dominick’s dataset indicates that coupons were used.
As a first test of the correlation between small price changes and sales volumes, we
merge the observations in all 29 categories. Across all categories, 26.6% of all price
changes are small (i.e., smaller, or equal to 10¢), and the average sales volume is 10.0
units per week. We then divide product-stores into deciles according to their sales
volume. Figure 1 depicts the results. An increase in the sales volume is associated with a
significant increase in the percentage of small price changes. The percentage of small
price changes in the 10th decile, 33.36%, is 2.4 times higher than the percentage of small
price changes in the 1st decile, 13.89%.
As a formal test, we estimate the following fixed effect regression model using the
pooled data:
(17)
where small price change is a dummy that equals 1 if a price change of product i in
store s in week t is less or equal to 10¢, and 0 otherwise. The average sales volume is for
product i in store s over the sample period.
8
By taking the average over a long period, we
obtain an estimate of the expected sales volume that does not depend on transitory shocks
7
Consider the following example. In week t, the price of a good was $1.99 and all units were sold at the posted price.
In week t+1, the posted price remained $1.99. 9 consumers bought at the posted price, and one used a coupon and paid
1.79. The price that would be recorded in the scanner dataset is $1.97, i.e, a 2 cents change relative to week t.
8
In calculating the average sales volume, we need to account for missing observations, because a missing observation
in week t implies that the product was either out of stock or had 0 sales on that week. Thus, averaging over the
available observations can lead to an upward bias for products that are sold in small numbers. Therefore, for each
product in each store, we calculate the average by first determining the total number of units sold over all available
observations. We then identify the first and last week for which we have observations, and calculate the average for
each product-store as
. The resulting figure is smaller than we would obtain if we averaged over all
available observations (which would not include obsservations on weeks with 0 sales).
10
or sales. X is a matrix of other control variables. Month and year are fixed effects for the
month (to control for seasonality) and the year of the price change. To control for the
differences across stores and products, we add ,
and
which are fixed effects for
categories, stores and products, respectively. u is an i.i.d error term.
Table 1 reports the estimates of the coefficients of the key variable, average sales
volume. Column 1 reports the results of a baseline regression that includes only the
average sales volume and fixed effects for months, years, stores, and products. The
coefficient of the sales volume is 0.026, and it is statistically significant. This result
suggests that a 1% increase in the sales volume is associated with a 2.6 percentage points
increase in the likelihood of a small price change. In column 2, the matrix X includes the
following control variables: the log of the average price, to control for the price level
effect on the size of price changes, the percentage change in the wholesale price, and
control for sale- and bounce-back prices. The latter is important as price changes
associated with sales tend to be large (Nakamura and Steinsson 2008).
9
The coefficient of the sales volume remains positive and statistically significant. Its
value is 0.017, suggesting that a 1% increase in the sales volume is associated with a 1.7
percentage points increase in the likelihood of a small price change.
In column 3, we add a dummy for 9-ending prices as an additional control because
when the pre-change price is 9-ending, price changes tend to be larger than when the pre-
change price ends in other digits (Levy et al. 2020). Thus, if products with high sales
volume tend to have non-9-ending prices, then it might lead to small changes in their
prices. This has only a marginal effect on the coefficient; its value remains 0.017 and
statistically significant.
In column 4, we keep the same control variables as in column 3, but we focus on
regular prices by excluding the sale- and bounce-back prices. We do this for two reasons.
First, sale- and bounce-back prices tend to be large, and therefore, we need to account for
them properly. Second, it is often argued that changes in sale prices have smaller effect
on inflation than changes in regular prices (Nakamura and Steinsson 2008, Midrigan
2011, Anderson et al. 2017, Ray et al. 2023).
We find that the estimate of the coefficient of the sales volume is 0.033, and is
statistically significant. The pooled results, therefore, suggest that there is a positive and
9
To identify sale prices, we do not use the sales’ flag included in the Dominick’s data because it was not set on a
consistent basis (Peltzman 2000). Instead, we use the sales filter algorithm of Fox and Syed (2016) to identify sales.
This algorithm has the advantage that it was calibrated using Dominick’s data and, consequently, it is particularly
useful for identifying sales in the Dominick’s data.
11
statistically significant correlation between small price changes and sales volumes.
4b. Results of category-level analyses
Estimation using pooled data can hide large differences across categories. Therefore,
we study the category-level correlation between small price changes and sales volumes.
As a first test, for each category, we group the products into high, medium, and low
sales volume products, according to the average sales volumes over the sample period.
Low sales volume products are products with average sales volume in the bottom third of
the distribution, high sales volume products have sales volume in the top third of the
distribution, and medium sales volume products have sales volume in between.
Figure 2 shows, for every category, the frequency of price changes for each size of
price change from 1¢ to 50¢. The red dashed line depicts the frequency of price changes
for high sales volume products, the black dotted line depicts the frequency of price
changes for medium sales volume products, and the blue solid line depicts the frequency
of price changes for low sales volume products. The shaded area marks the range of small
price changes,
10¢P
.
The figure shows that the most common price changes are multiples of 10¢ (as
reported also by Chen et al. 2008 and Levy et al. 2011). It can also be observed that in all
categories except cigarettes (which are highly regulated), price changes are far more
common among high sales volume products than among low sales volume products.
Focusing on the shaded area, we see that the frequency of small price changes is in
general far greater among the high sales volume products than among low sales volume
products. Indeed, for high sales volume products, in most categories, the frequency of
small price changes exceeds the frequency of large price changes. This is less common,
and less dramatic, among low sales volume products. For the medium sales volume
products, the frequency of price changes, and the frequency of small price changes in
particular, fall in between the frequencies of the low and high sales-volume products.
As a formal test, we estimate a series of category-level fixed-effect regressions,
similar to (17). The only difference is that we now exclude the category fixed effects.
Table 2 reports the coefficients of the key variable, average sales volume, for each
product category. Column 1 reports the results of baseline regressions that exclude the X
matrix. I.e, the regressions include only the average sales volume and fixed effects for
months, years, stores, and products.
We find that in all 29 product categories, the coefficients are positive, and 27 are
statistically significant. One more is marginally significant. In other words, in 28 of 29
12
product categories, there is a positive and statistically significant correlation between the
likelihood that a price change is small and the average sales volume. The effect is
economically significant. The average coefficient is 0.026, suggesting that an increase of
1% in the sales volume is associated with an increase of 2.6 percentage points in the
likelihood that a price change will be small.
In column 2, we add the X matrix which includes the following control variables: the
log of the average price to control for the price level effect, the percentage change in the
wholesale price, and control for sale- and bounce-back prices, all as defined above. The
results are similar to column 1. The coefficients of the average sales volume are positive
and statistically significant in 27 categories, and marginally significant in 2 more. The
average coefficient is 0.019. Thus, even after including the controls, we still find that
increasing the average sales volume by 1% is associated with an increase of 1.9
percentage points in the likelihood of a small price change.
In column 3, we add a dummy for 9-ending prices as an additional control. Adding
this dummy does not change the main result appreciably. All 29 coefficients remain
positive. 27 are statistically significant, and 2 more marginally significant. Controlling for
9-ending prices, increasing the average sales volume by 1% is associated with a 2.0
percentage points increase in the likelihood of a small price change, on average.
In column 4, we focus on regular prices by excluding the sale- and bounce-back
prices. We find that all the coefficients remain positive. 27 are statistically significant,
and 1 more is marginally significant. The average coefficient is 0.038, implying that for
regular prices, an increase of 1% in the average sales volume is associated with an
increase of 3.8 percentage points in the likelihood of a small price change.
4c. Results of product-level analyses
A possible explanation for the correlation between sales volume and small price
changes is that products with high sales volume have some unobserved attributes that
make them prone to small price changes. We explore this possibility by estimating for
each product a separate regression. If the correlation between sales volume and small
price changes is found at the level of individual products, then it cannot be explained by
unobserved attributes, since in each regression we have data on only one product.
Before presenting the full regression results, consider as an example the bathroom
tissue category. In Figure 3, we show a scatter plot for each one of the 13 bathroom-tissue
products that have data for all 93 stores at Dominick’s. In each of the 13 panels, there are
93 dots, one for each store. In each figure, the x-axis in the figures gives the average
13
weekly sales volume of the product in a store, and the y-axis gives the share of small
price changes of the product in a store. The straight lines are regression lines.
According to the plots, the correlation between sales volume and the share of small
price changes is positive for 11 of the 13 individual products. None of the negative
correlations is statistically significant, while 8 of the 11 positive correlations (marked
with solid black regression lines) are statistically significant. The regression lines that are
not statistically significant are marked with red dotted lines.
For a more formal analysis, we calculate for each product in each of the 29 product
categories the average weekly sales volume and the share of small price changes in each
of the stores it was offered. Many products in the sample were offered for only short
periods or only in a small number of stores. To avoid biases, we drop products for which
we do not have information for at least 30 stores.
Using these data, we estimate for each product in each category an OLS regression
with robust standard errors. The dependent variable is the share of small price changes
for the product in each store. The independent variable is the average sales volume of the
product in each store. The estimation results are summarized in Table 3.
10
Column 1 gives, for each product category, the average of the estimated coefficients.
Columns 2–5 give information on the sign of the estimated coefficients: the total number
of coefficients, the % of positive coefficients, the total number of coefficients that are
statistically significant at the 5% level, and the % of coefficients that are both positive
and statistically significant at the 5% level.
According to the figures in the table, the average coefficients are positive in 28 of the
29 product categories. The only exception is the highly regulated cigarettes category,
which is often excluded from the analyses (Chen et al. 2008, p. 729, footnote 2). In
addition, the number of positive coefficients far exceeds the number of negative
coefficients. On average, the former is 3.2 times larger than the latter. Ignoring the
cigarettes category, more than 74.5% of the coefficients are positive.
Focusing on statistically significant coefficients, we find a far greater number of
positive coefficients than negative coefficients that are significant. Except for the
cigarettes category, in all categories, 81.40%–100% of the statistically significant
coefficients are positive. In other words, for the overwhelming majority of the individual
products in our sample, we find a positive relationship between sales volume and the
10
For robustness, we have also conducted an analysis using LPM regressions, as in the previous section. See the
discussion in Online Supplementary Web Appendix F.
14
share of small price changes.
To summarize, we find that the correlation between sales volume and the share of
small price changes is positive whether we look across categories, within categories, and
for individual products across stores. It seems unlikely, therefore, that the correlation is
due to unobserved characteristics of the products or the product categories.
4d. Sales volume versus revenue
Kang and Usher (2023) find that the size of price changes is negatively correlated
with the revenue. In column 1 of Table 4, we report the Pearson correlation coefficient
between the average sales volume and the average revenue for product-stores for each
product category. The average correlation is 0.85, suggesting that at the category level,
the correlation is very strong.
In column 2, we replicate one of Kang and Usher’s (2023) key findings by reporting
for each product category, the coefficient estimates of regression (16) where we replace
the log of the average sales volume with the log of the average revenue. The controls
include fixed effects for months, years, stores, and products. The estimated coefficients
are positive for all 29 product categories, and 28 of these are statistically significant. We
thus confirm that Kang and Usher’s (2023) findings hold in our data: there is a strong
positive correlation between revenue and the likelihood of a small price change.
Revenue, however, is a product of the sales volume and the price. Our hypothesis
implies that the revenue is correlated with the likelihood of a small price change via the
sales volume, rather than via the price. To test this, in columns 3 and 4, we show the
results of regressions that include both the sales volume and the revenue as independent
variables. Once we add the sales volume to the regression, the coefficients of the revenue
turn negative in 22 of the 29 categories. The coefficients of the sales volume, on the other
hand, are positive in 23 of the 29 categories.
These results suggest that holding the sales volume constant, the higher the price
level, the less frequent small price changes are. In other words, the positive correlation
between revenues and the frequency of small price changes seems to materialize through
the sales volume and not through the price.
4e. Sales volume, producer size, and price synchronization
According to Lach and Tsiddon (2007), Midrigan (2011), Alvarez and Lippi (2014),
Letterie and Nilsen (2014), and Alvarez et al. (2016), small price changes can be
explained by economies of scale in price adjustment, which makes small price changes
15
profitable if the average price change exceeds the menu cost. Lach and Tsiddon (2007)
and Bhattarai and Schoenle (2014) show that: (a) producers offering a large number of
products are more likely to make small price changes than producers offering a small
number of products, (b) small price changes are more likely when price changes are more
synchronized, and (c) small price changes are more likely when the average size of all
other contemporaneous price changes is high. In addition, Bhattarai and Schoenle (2014)
provide evidence suggesting that producers offering more products are more likely to
have a large sales volume. It is therefore of interest to examine whether our results hold
when accounting for economies of scope by adding controls for price changes
synchronization and the number of products per producer.
In column 1 of Table 5, we report the coefficients of the log of sales volume in
regression (17), where we also include the average number of products per category
offered by the same producer, as a proxy to the producer’s size.
11
The regression also
includes fixed effects for months, years, stores, and products. We find that all coefficients
of the sales volume are positive and 27 are statistically significant. In addition, the
coefficients of the sales volume are almost unaffected in comparison to the figures we
report in column 1 of Table 3. Thus, it appears that the effects of sales volume on the
likelihood of small price changes are unrelated to the effects of the size of the producers.
In column 2, we add a control for the percentage of the products that changed the
price in the same week, excluding the current observation. Again, the coefficients remain
almost unchanged in comparison to the figures we report in column 1 of Table 3.
In column 3, we further add the average size of contemporaneous price changes,
excluding the current observation. Lach and Tsiddon (2007) show that when price
changes are synchronized, a small price change is correlated with a large average
contemporaneous price change. However, we find that adding the average size of price
changes has little effect on the size of the coefficients of the sales volume. Also in this
specification, 27 of the 29 coefficients are statistically significant.
Finally, in column 4, we add the percentage of the products that are produced by the
same producer and changed price in the same week, excluding the current observation.
This forces us to drop some observations because we can only use an observation if the
producer offers at least two products on the relevant week. The upshot is that most of the
remaining observations are of products produced by relatively large producers which are
11
To calculate the average number of products offered by a producer, we follow Bhattarai and Schoenle (2014), by
first determining the nubmer of products offered by a producer each week, and then averaging over all weeks.
16
most likely to make small price changes (Bhattarai and Schoenle 2014).
Therefore, if our results are driven by the size of the producers rather than by the
sales volume, then focusing on large producers should lead to a substantial drop in the
coefficients of the sales volume. We find, however, that the results do not change
significantly. All the coefficients are positive, 27 of the 29 of them are statistically
significant, and 2 more are marginally significant.
As another test, we follow Bonomo et al. (2022). They show that a large share of
price changes takes place on “peak days.” We therefore follow their methodology and
create a dummy for peak days and then add it as a control to the regressions. The
estimation results, which we present and discuss in Online Supplementary Web Appendix
P, show that the correlation between sales volumes and small price changes holds also
when we control for peak days.
5. Robustness
To assess the robustness of our findings, we conducted 19 sets of robustness tests:
1) Measurement errors: Eichenbaum et al. (2014) conclude that prices based on scanner
data might include spurious small price changes. We mitigate this concern by
focusing only on price changes in which the post change price remained unchanged
for at least 2 weeks. As further tests, we exclude all 1¢ and 2¢ price changes
(Eichenbaum et al. 2014), and remove observations on price changes if Dominick’s
sale flag indicates that there was a coupon use because if some consumers used
coupons, this could result in measurement errors (Eichenbaum et al. 2014). We also
estimate the regressions using observations on all price changes, conditional on
observing the prices in weeks t and t+1.
2) Definition of small price changes: We define a small price change as a price change
of 5¢ or less, and 15¢ or less. Because the size of price changes may be larger for
more expensive products, we re-run the analyses by defining a small price change in
percent as a price change of 2% or less, and 5% or less. Following Midrigan (2011)
and Bhattarai and Schoenle (2014), we also define small price changes relative to the
average price change at the store-product level. I.e., a price change is small if it is
smaller or equal to
, where
is the average price change for product in
store , and attains the values (8) 0.50, (9) 0.33, (10) 0.25 and (11) 0.10.
3) Time horizon for computing the average sales volume: Above, we use the average
sales volume over the entire period, which can be thought of as a proxy for the
17
expected sales volume that is based on 8 years of data. However, this implicitly
assumes that in the first years, the retailer can predict the future sales volume. An
alternative is that the retailer makes decisions based on recent sales data. We,
therefore repeat the analyses by calculating the average sales volume based on a
rolling 52-week window of past observations.
4) Competition effect: As another control for the effect of competition, we add control
for Dominick’s pricing zones. We re-estimate the product-level regressions by
augmenting the data with demographic information of the consumers that live in the
proximity of each store, including their median income, the share of minorities, and
the share of unemployed.
5) Controlling for revenue: In section 4d, we estimate regressions with both the sales
volume and the revenue at the category level. For robustness, we explore the effect of
adding further controls. In addition, at the category level, the high correlation
between the sales volume and the revenue may render the results suspect. Therefore,
we pool data from all categories together and re-estimate the regressions. We also test
an alternative definition of the average revenue, defining it as the product of the
average sales volume and the average price for estimating category-level regressions.
6) Controlling for the producers’ size: In section 4e, we calculate the number of
products offered by each producer at the category level. To test that the results do not
change for firms of different sizes, we follow Bhattarai and Schoenle (2014) in
dividing producers into bins according to the number of products they offer in each
category and estimate the correlation between sales volume and small price changes
for each bin separately. In addition, it is possible that producers that offer products in
more than one category synchronize price changes across categories, We, therefore,
pool the data together and repeat the analysis.
7) Controlling for profit margins: Some products have high sales volumes, yet they
have few, if any, small price changes. One example is iPhones, which have high sales
volumes, yet most of their price changes are large. A possible explanation is that
small price changes are less likely for products with large markups because large
markups imply that small price changes have, in percentage terms, only a small effect
on total profits. We, therefore, add Dominick’s measure of markups to the category-
level regressions as a further control variable.
8) Graphic illustration of the category-level correlation between small price changes
and sales volume: We include a figure similar to Figure 1, which shows that small
18
price changes are correlated with high sales volume at the category level as well as at
the aggregate level.
9) Reproduce Figure 2 using % price changes: In Figure 2, the most common price
changes are multiples of 10 cents. This is consistent with a large literature on price
points (Levy et al., 2011, 2020). However, because price changes that are multiples of
10 cents might be large for some products, we reproduce Figure 2 using the size of
price changes in % terms rather than in cents.
10) National brands vs. private labels: A possible explanation for our results is that the
correlation between sales volume and small price changes is an artifact of differences
in demand. We, therefore, separate the data into two groups: national brands and
private labels, since the demand for private labels is likely to exhibit different patterns
than for national brands.
11) Holiday price rigidity: Levy et al. (2010) provide evidence suggesting that menu
costs are higher than normal during the Thanksgiving-Christmas holiday period. It is,
therefore, possible that there are fewer small price changes during the Thanksgiving-
Christmas period, leading to a decline in the correlation between sales volumes and
small price changes. We, therefore, re-estimate equation 1, using only the
observations from the Thanksgiving-Christmas period.
12) Another prediction of Barro’s (1972) model: In the paper, we study the correlation
between small price changes and sales volumes. However, Barro’s (1972) model, as
shown in section 2, also predicts that sales volume should also be correlated with the
number of price changes. In other words, prices of products with high sales volumes
should change more frequently than the prices of products with low sales volumes.
We test this hypothesis in the appendix.
13) Controlling for peak days: Bonomo et al. (2022) show that in their data, the majority
of price changes occur during “peak days.” Following their definition, for each
category in each store, we identify peak days as the subset of the most active days
that jointly account for one-half of all price changes in a store over the entire sample
period. We then control for peak days in the regressions.
14) Cross-category comparisons: We show that there are large variations in both the
average sales volume and the likelihood of small price changes across categories. We
then show that as we hypothesize, some of the variation in the likelihood of small
price changes can be explained by the average sales volumes.
15) Excluding observations on the multi-unit package: Some of the products in our
19
dataset are composed of several units. For example, we have products such as 6-packs
of beer, or a 4-pack of canned tuna. Above, we treat such packages as a single good,
because the consumer pays once for the entire package. However, these may add
noise to the regression, because it is unclear how consumers perceive such packages.
We, therefore, exclude such multi-unit packaged goods and focus on products that are
sold in single units.
16) Product level regressions: We show that the results we obtained for the product level
correlation between small price changes and sales volumes hold when we add further
controls and when we estimate the correlations using linear probability models.
17) Storable vs. non-storable products: Retailers might employ different strategies for
storable vs. non-storable products. We therefore test for the robustness of our results
by assessing them separately for storable and non-storable products.
18) Asymmetry in the correlations: Our model predicts a symmetric correlation between
sales volumes and the likelihood of small price changes. However, it is possible that
the correlation is asymmetric, for example, if shoppers are not attentive to small price
changes (Chen et al., 2008, Chakraborty et al., 2015). We therefore estimate separate
regressions for price increases and price decreases.
19) Cross-category analysis: We conduct further analysis comparing the likelihood of
small price changes and the sales volumes across categories.
The Online Supplementary Appendix contains the details of these analyses. Overall,
our main results are broadly unchanged, and are robust across the different specifications.
6. Conclusion and policy implications
The finding of frequent small price changes in many retail price datasets has been
interpreted by authors as prima facie evidence against simple menu cost models. We find,
however, that sales volume can explain some of the small price changes found in many
datasets. When a retailer expects to sell many units, then small price changes can be
profitable even in the presence of lump sum menu costs.
We use Dominick’s scanner price dataset to show a strong positive correlation
between the frequency of small price changes and products’ sales volume. This finding is
robust. It holds across product categories, within product categories, and for individual
products. It is also robust to a variety of sensitivity analyses such as the definition of
“small” price changes, measurement errors, the inclusion of control variables, firms’ size,
price synchronization, and the time horizon used to compute the average sales volume.
20
Our findings hold irrespective of how we measure price changesin absolute or relative
terms. The latter is useful if one wants to assess the “Calvo-ness” of the relevant model.
Our findings are consistent with the findings reported by Bhattarai and Schoenle
(2014) and Kang and Usher (2023), who employ more recent datasets. However, the
advantage of Dominick’s dataset, in comparison to more recent datasets is its richness. In
addition to prices and sales volume—two critical variables for our analyses, it also
contains data on wholesale prices, promotions and sales, pricing zones, shoppers’ socio-
demographics, markups, etc. We employ these additional variables to check robustness.
Above, we use Barro’s (1972) model to illustrate the theoretical correlation between
sales volumes and the size of price changes. However, Barro’s (1972) model is too
stylistic for deriving predictions about the distribution of the size of price changes. In
addition, it cannot predict the number of small price changes observed in many datasets
unless we assume unrealistically high sales volumes. Therefore, we believe that there is a
need for models that will account for sales volumes, perhaps along the lines of Golosov
and Lucas (2007). It would then be possible to evaluate the implications of heterogeneity
in sales volumes for the macro-level price rigidity.
Such a model might yield important insights. First, it might yield a non-trivial
distribution of the size of price changes even if all producers sell one product and the
menu costs are fixed. Second, if the size of price changes depends on the sales volume,
then the existence of small price changes does not rule out selection. Thus, unlike many
of the existing models, in such a model, the kurtosis of the distribution of the size of price
changes might not necessarily indicate selection (Alvarez et al., 2016). Therefore, for a
given frequency of price changes, we might obtain a result where a monetary shock has
only a small real effect even in the presence of many small price changes (Kang and
Usher, 2023). Related to this, Karadi et al. (forthcoming) find that the likelihood of a
price change does not depend on the gap between the price and the optimal price. They
interpret their finding as evidence against selection. However, in a model where price
changes depend on sales volumes, we may have selection together with both small and
large price changes in response to a monetary shock.
21
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25
Table 1. Pooled regressions of small price changes and sales volume
(1)
(2)
(3)
(4)
Average sales
volume
0.026***
(0.001)
0.017***
(0.001)
0.017***
(0.001)
0.033***
(0.001)
Observations
9,553,542
9,553,542
9,553,542
2,328,405
Notes: The dependent variable is “small price change,” which equals 1 if a price change of product i in
store s at time t is less or equal to 10¢, and 0 otherwise. The main independent variable is the log of the
average sales volume of product i in store s over the sample period. Column 1 reports the results of a
baseline regression that includes only the average sales volume and the fixed effects for months, years,
stores, and products. In column 2, we add the following controls: the log of the average price, the log of the
absolute change in the wholesale price, and a control for the sale- and bounce-back prices, which we
identify using a sales filter algorithm. In column 3, we add a dummy for 9-ending prices as an additional
control. In column 4, we focus on regular prices by excluding the sale- and bounce-back prices. All
regressions also include fixed effects for categories, stores, products, years, and months. We estimate
separate regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%,
*** p < 1%
26
Table 2. Category-level regressions of small price changes and sales volume
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient (Std.)
0.0262*** (0.0034)
0.019*** (0.0032)
0.0188*** (0.0031)
0.029*** (0.0068)
Observations
144,461
144,461
144,461
44,950
Bath Soap
Coefficient (Std.)
0.0293*** (0.008)
0.0277*** (0.0082)
0.0285*** (0.0081)
0.0972*** (0.0192)
Observations
15,295
15,295
15,295
3,208
Bathroom
Tissues
Coefficient (Std.)
0.0408*** (0.007)
0.0179** (0.0058)
0.0184*** (0.0057)
0.0386*** (0.0084)
Observations
149,441
149,441
149,441
47,041
Beer
Coefficient (Std.)
0.013*** (0.0012)
0.0147*** (0.0012)
0.0147*** (0.0012)
0.0699*** (0.0063)
Observations
290,620
290,620
290,620
27,348
Bottled Juice
Coefficient (Std.)
0.0329*** (0.0053)
0.0239*** (0.0044)
0.0238*** (0.0045)
0.0304*** (0.0063)
Observations
496,557
496,557
496,557
133,714
Canned Soup
Coefficient (Std.)
0.0158*** (0.0056)
0.0108* (0.005)
0.0134** (0.0049)
0.0144** (0.0049)
Observations
495,543
495,543
495,543
176,235
Canned Tuna
Coefficient (Std.)
0.0237*** (0.0054)
0.0134** (0.0046)
0.0131** (0.0045)
0.0225*** (0.0058)
Observations
213,043
213,043
213,043
64,161
Cereals
Coefficient (Std.)
0.0204*** (0.0037)
0.0149*** (0.0034)
0.0148*** (0.0034)
0.0188*** (0.0046)
Observations
357,120
357,120
357,120
155,367
Cheese
Coefficient (Std.)
0.0201*** (0.0028)
0.0113*** (0.0025)
0.0112*** (0.0025)
0.0113*** (0.0033)
Observations
796,150
796,150
796,150
224,889
Cigarettes
Coefficient (Std.)
0.0084** (0.0046)
0.0073
(0.0045)
0.0074
(0.0044)
0.0069
(0.0054)
Observations
36,157
36,157
36,157
30,262
Cookies
Coefficient (Std.)
0.0267*** (0.0018)
0.022*** (0.0017)
0.0223*** (0.0017)
0.046*** (0.0035)
Observations
688,761
688,761
688,761
132,488
Crackers
Coefficient (Std.)
0.0379*** (0.0031)
0.0302*** (0.0026)
0.0306*** (0.0026)
0.0467*** (0.0072)
Observations
245,185
245,185
245,185
50,029
Dish
Detergent
Coefficient (Std.)
0.0393*** (0.0044)
0.028*** (0.0036)
0.0279*** (0.0035)
0.0361*** (0.0041)
Observations
189,633
189,633
189,633
53,289
Fabric
Softener
Coefficient (Std.)
0.0238*** (0.0048)
0.0123*** (0.0043)
0.0126*** (0.0043)
0.0325*** (0.0057)
Observations
181,056
181,056
181,056
56,234
Front-End-
Candies
Coefficient (Std.)
0.0047
(0.0041)
0.0057
(0.0033)
0.0059
(0.0032)
0.0053
(0.0031)
Observations
278,853
278,853
278,853
111,635
Frozen
Dinners
Coefficient (Std.)
0.0475*** (0.0034)
0.036*** (0.0028)
0.0389*** (0.0027)
0.0795*** (0.0066)
Observations
203,191
203,191
203,191
37,527
27
Table 2. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient (Std.)
0.028*** (0.0021)
0.0259*** (0.0019)
0.0266*** (0.0019)
0.0443*** (0.0034)
Observations
864,832
864,832
864,832
213,545
Frozen Juices
Coefficient (Std.)
0.0273*** (0.0048)
0.0198*** (0.0042)
0.0206*** (0.0041)
0.0293*** (0.0062)
Observations
308,817
308,817
308,817
87,919
Grooming
Products
Coefficient (Std.)
0.0187*** (0.0023)
0.0209*** (0.0024)
0.021*** (0.0024)
0.0417*** (0.0069)
Observations
269,873
269,873
269,873
51,819
Laundry
Detergents
Coefficient (Std.)
0.0196*** (0.0032)
0.0093*** (0.0028)
0.0097*** (0.0028)
0.02*** (0.0045)
Observations
272,765
272,765
272,765
85,184
Oatmeal
Coefficient (Std.)
0.028*** (0.008)
0.0152* (0.0067)
0.0154* (0.0067)
0.0338*** (0.0098)
Observations
79,983
79,983
79,983
36,043
Paper Towels
Coefficient (Std.)
0.0454*** (0.0105)
0.0316*** (0.0118)
0.0321*** (0.0119)
0.0378*** (0.0115)
Observations
116,204
116,204
116,204
29,280
Refrigerated
Juices
Coefficient (Std.)
0.0357*** (0.0047)
0.0209*** (0.0039)
0.0209*** (0.0039)
0.033*** (0.0056)
Observations
306,865
306,865
306,865
72,031
Shampoos
Coefficient (Std.)
0.0162*** (0.0015)
0.02*** (0.0016)
0.0201*** (0.0015)
0.046*** (0.0052)
Observations
261,778
261,778
261,778
40,996
Snack
Crackers
Coefficient (Std.)
0.0319*** (0.0032)
0.0282*** (0.003)
0.0284*** (0.003)
0.0518*** (0.0052)
Observations
398,665
398,665
398,665
78,581
Soaps
Coefficient (Std.)
0.0374*** (0.0055)
0.0226*** (0.005)
0.0237*** (0.005)
0.049*** (0.0076)
Observations
152,379
152,379
152,379
46,829
Soft Drinks
Coefficient (Std.)
0.0211*** (0.0017)
0.024*** (0.0013)
0.023*** (0.0012)
0.0517*** (0.0037)
Observations
1,350,618
1,350,618
1,350,618
156,004
Toothbrushes
Coefficient (Std.)
0.0204*** (0.0028)
0.02*** (0.0028)
0.0195*** (0.0028)
0.0498*** (0.0076)
Observations
125,380
125,380
125,380
24,955
Toothpastes
Coefficient (Std.)
0.0123*** (0.0026)
0.0111*** (0.0022)
0.0111*** (0.0022)
0.0393*** (0.0063)
Observations
264,317
264,317
264,317
56,842
Average coefficients
0.0260
0.0195
0.0198
0.0384
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 10¢, and 0 otherwise. The main independent variable is the log of the average sales volume of product i in
store s over the sample period. Column 1 reports the results of baseline regression that includes only the average sales
volume and the fixed effects for months, years, stores, and products. In column 2, we add the following controls: the
log of the average price, the log of the absolute change in the wholesale price, and control for sale- and bounce-back
prices, which we identify using a sales filter algorithm. In column 3, we add a dummy for 9-ending prices as an
additional control. In column 4, we focus on regular prices by excluding the sale- and bounce-back prices. We estimate
separate regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
28
Table 3. Product-level regressions of the % of small price changes and sales volume
by categories
Product
Category
Average
coefficient
estimate
(1)
Number
of
coefficients
(2)
Percentage of
positive
coefficients
(3)
Number of
significant
coefficients
(4)
% of positive and
significant
coefficients
(5)
Analgesics
0.031
213
83.20%
87
98.25%
Bath Soaps
0.034
33
69.77%
14
100.00%
Bathroom tissues
0.057
100
79.31%
34
90.24%
Beers
0.019
202
91.57%
142
97.80%
Bottled juices
0.051
370
83.67%
192
84.56%
Canned soups
0.041
348
77.41%
145
90.37%
Canned tuna
0.037
181
76.16%
60
80.00%
Cereals
0.047
345
80.13%
99
89.32%
Cheese
0.036
474
81.76%
224
90.26%
Cigarettes
-0.020
107
71.43%
4
40.00%
Cookies
0.034
667
82.42%
304
94.71%
Crackers
0.044
212
88.41%
118
98.84%
Dish detergents
0.041
199
85.71%
84
91.89%
Fabric softeners
0.043
226
85.35%
69
91.67%
Front end candies
0.053
275
75.28%
92
91.03%
Frozen dinners
0.053
215
92.06%
131
97.59%
Frozen entrees
0.052
671
89.32%
363
97.46%
Frozen juices
0.032
142
75.00%
62
97.67%
Grooming products
0.011
531
80.94%
229
90.65%
Laundry detergents
0.018
406
75.00%
101
81.40%
Oatmeal
0.047
69
76.81%
20
84.62%
Paper towels
0.052
90
73.61%
33
90.91%
Refrigerated juices
0.036
176
73.08%
77
85.92%
Shampoos
0.022
614
82.78%
282
96.72%
Snack crackers
0.041
282
87.36%
172
92.55%
Soaps
0.039
217
80.55%
421
84.31%
Soft drinks
0.032
902
82.49%
72
94.87%
Toothbrushes
0.026
204
82.84%
89
95.83%
Toothpastes
0.015
337
79.67%
99
92.75%
Average
0.035
303
73.29%
96
90.08%
Notes: For each product category, column 1 presents the average estimated coefficients. Column 2 presents the total
number of coefficients. Column 3 presents the % of positive coefficients out of all coefficients. Column 4 presents the
total number of coefficients that are statistically significant at the 5% level. Column 5 presents the % of coefficients
that are positive and statistically significant, at the 5% level. Products are identified by their UPCs.
29
Table 4. Category-level regressions of small price changes, sales volume, and revenue
Category
Correlation
Revenue
Sales volume and revenue
(1)
(2)
(3)
(4)
(4)
Analgesics
Coefficient (Std.)
0.8088
0.0244*** (0.0035)
0.2246*** (0.0463)
-0.201*** (0.0467)
Observations
144,461
Bath Soap
Coefficient (Std.)
0.7757
0.0319*** (0.0082)
-0.3214** (0.1271)
0.3527* (0.1279)
Observations
15,295
Bathroom
Tissues
Coefficient (Std.)
0.7838
0.036*** (0.0062)
0.8456*** (0.1168)
-0.8195*** (0.1169)
Observations
149,441
Beer
Coefficient (Std.)
0.8642
0.0131*** (0.0012)
-0.0562* (0.0288)
0.0692** (0.0287)
Observations
290,620
Bottled Juice
Coefficient (Std.)
0.9138
0.0305*** (0.0052)
0.8371*** (0.1025)
-0.8065*** (0.1027)
Observations
496,557
Canned Soup
Coefficient (Std.)
0.9458
0.0148*** (0.0056)
0.5075*** (0.0785)
-0.4943*** (0.0791)
Observations
495,543
Canned Tuna
Coefficient (Std.)
0.863
0.0201*** (0.0054)
0.5276*** (0.1175)
-0.5093*** (0.1183)
Observations
213,043
Cereals
Coefficient (Std.)
0.9311
0.0203*** (0.0038)
0.0634
(0.0429)
-0.0433 (0.0437)
Observations
357,120
Cheese
Coefficient (Std.)
0.86
0.018*** (0.0029)
0.4048*** (0.1085)
-0.3846*** (0.1091)
Observations
796,150
Cigarettes
Coefficient (Std.)
0.9938
0.0102** (0.0046)
-0.3209*** (0.0622)
0.3303*** (0.062)
Observations
36,157
Cookies
Coefficient (Std.)
0.9485
0.0273*** (0.0018)
-0.0045 (0.022)
0.0318
(0.0221)
Observations
688,761
Crackers
Coefficient (Std.)
0.9536
0.038*** (0.0031)
0.1257** (0.0554)
-0.0881 (0.056)
Observations
245,185
Dish
Detergent
Coefficient (Std.)
0.8123
0.038*** (0.0043)
0.4862*** (0.1382)
-0.4511*** (0.1376)
Observations
189,633
Fabric
Softener
Coefficient (Std.)
0.7951
0.0181*** (0.0048)
0.9508*** (0.2067)
-0.9307*** (0.208)
Observations
181,056
Front−End−C
andies
Coefficient (Std.)
0.8611
0.0045
(0.0042)
0.8471*** (0.075)
-0.8406*** (0.0755)
Observations
278,853
Frozen
Dinners
Coefficient (Std.)
0.726
0.0471*** (0.0033)
0.2111*** (0.0446)
-0.162*** (0.044)
Observations
203,191
502,792 502,792
30
Table 4 (Cont.)
Category
Correlation
Revenue
Sales volume and Revenue Correlation
(1)
(2)
(3) (4)
Frozen Entrees
Coefficient (Std.)
0.8584
0.0271*** (0.002)
0.1611*** (0.0155)
-0.1321*** (0.0153)
Observations
864,832
Frozen Juices
Coefficient (Std.)
0.9651
0.0255*** (0.005)
0.2732*** (0.068)
-0.2456*** (0.0687)
Observations
308,817
Grooming
Products
Coefficient (Std.)
0.811
0.0188*** (0.0024)
0.0026
(0.0378)
0.0162
(0.0382)
Observations
269,873
Laundry
Detergents
Coefficient (Std.)
0.9153
0.0174*** (0.0031)
0.3272***
(0.061)
-0.311***
(0.0604)
Observations
272,765
Oatmeal
Coefficient (Std.)
0.8775
0.0293*** (0.0082)
-0.0121
(0.0248)
0.0416
(0.0255)
Observations
79,983
Paper Towels
Coefficient (Std.)
0.7593
0.0395*** (0.0107)
0.8975***
(0.204)
-0.8574***
(0.2028)
Observations
116,204
Refrigerated
Juices
Coefficient (Std.)
0.9201
0.0351*** (0.0048)
0.1247** (0.0586)
-0.09
(0.0592)
Observations
306,865
Shampoos
Coefficient (Std.)
0.7226
0.0162*** (0.0015)
0.0171
(0.0162)
-0.0008 (0.0162)
Observations
261,778
Snack
Crackers
Coefficient (Std.)
0.9124
0.0324*** (0.0033)
0.0736 (0.083)
-0.0414 (0.0839)
Observations
398,665
Soaps
Coefficient (Std.)
0.6725
0.0359*** (0.0055)
0.4935*** (0.0435)
-0.4684*** (0.0429)
Observations
152,379
Soft Drinks
Coefficient (Std.)
0.756
0.0207*** (0.0017)
0.5154*** (0.1761)
-0.4784*** (0.1763)
Observations
1,350,618
Toothbrushes
Coefficient (Std.)
0.82
0.0202*** (0.0029)
0.045
(0.0418)
-0.0247 (0.0419)
Observations
125,380
Toothpastes
Coefficient (Std.)
0.8902
0.0137*** (0.0026)
-0.1035*** (0.0373)
0.1181*** (0.0373)
Observations
264,317
Average coefficients
0.8523
0.03397
0.1902
0.1705-
Notes: Column 1 reports the Pearson correlation coefficient between the sales volume and revenues for each category.
Columns 2–4 report the results of category-level fixed effect regressions of the probability of a small price change. The
dependent variable in all columns is “small price change,” which equals 1 if a price change of product i in store s at time
t is less or equal to 10¢, and 0 otherwise. In column 2, the main independent variable is the log of average revenue for
product i in store s over the sample period. In columns 3 and 4, we report the results of a regression that includes both
the log of the sales volume and the log of the revenue as independent variables. Column 3 reports the coefficients of the
sales volume. Column 4 reports the coefficients of the revenue. All regressions also include fixed effects for months,
years, stores, and products. We estimate separate regressions for each product category, clustering the errors by product.
* p < 10%, ** p < 5%, *** p < 1%
31
Table 5. Category-level regressions of small price changes and synchronization
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient (Std.)
0.026*** (0.0034)
0.0258*** (0.0034)
0.024*** (0.0034)
0.0245*** (0.0033)
Observations
144,461
144,461
143,780
139,228
Bath Soap
Coefficient (Std.)
0.0313*** (0.0077)
0.0307*** (0.0077)
0.0266*** (0.0086)
0.0243*** (0.0088)
Observations
15,295
15,288
13,228
10,538
Bathroom
Tissues
Coefficient (Std.)
0.0406*** (0.007)
0.0402*** (0.007)
0.0398*** (0.007)
0.0436*** (0.0073)
Observations
149,441
149,441
148,926
139,207
Beer
Coefficient (Std.)
0.0123*** (0.0013)
0.0114*** (0.0012)
0.0114*** (0.0012)
0.0119*** (0.0013)
Observations
290,620
290,617
290,524
267,233
Bottled Juice
Coefficient (Std.)
0.0357*** (0.0052)
0.0356*** (0.0052)
0.0348*** (0.0052)
0.0357*** (0.0054)
Observations
496,557
496,555
496,461
485,670
Canned Soup
Coefficient (Std.)
0.0174*** (0.0056)
0.0174*** (0.0056)
0.0172*** (0.0055)
0.0169*** (0.0056)
Observations
495,543
495,543
495,276
490,981
Canned Tuna
Coefficient (Std.)
0.0229*** (0.0053)
0.0226*** (0.0053)
0.023*** (0.0053)
0.0234*** (0.0056)
Observations
213,043
213,043
212,567
202,922
Cereals
Coefficient (Std.)
0.0205*** (0.0037)
0.0205*** (0.0037)
0.0195*** (0.0035)
0.0205*** (0.0034)
Observations
357,120
357,120
357,077
352,500
Cheese
Coefficient (Std.)
0.02*** (0.0028)
0.0198*** (0.0028)
0.0198*** (0.0028)
0.0198*** (0.003)
Observations
796,150
796,148
796,142
758,753
Cigarettes
Coefficient (Std.)
0.007
(0.0051)
0.0076 (0.005)
0.0081
(0.0051)
0.0091* (0.0047)
Observations
36,157
36,152
35,824
35,408
Cookies
Coefficient (Std.)
0.0272*** (0.0019)
0.0278*** (0.0019)
0.0275*** (0.0019)
0.0277*** (0.0019)
Observations
688,761
688,759
688,726
681,886
Crackers
Coefficient (Std.)
0.0378*** (0.0031)
0.0379*** (0.0031)
0.0369*** (0.003)
0.0359*** (0.003)
Observations
245,185
245,183
244,898
236,163
Dish
Detergent
Coefficient (Std.)
0.0396*** (0.0045)
0.0387*** (0.0045)
0.0372*** (0.0043)
0.0394*** (0.0041)
Observations
189,633
189,633
189,182
185,996
Fabric
Softener
Coefficient (Std.)
0.0255*** (0.0048)
0.0252*** (0.0048)
0.0227*** (0.0047)
0.0239*** (0.0048)
Observations
181,056
181,056
180,721
168,434
Front-End-
Candies
Coefficient (Std.)
0.0042
(0.0041)
0.0032
(0.0041)
0.0054
(0.0034)
0.0064* (0.0035)
Observations
278,853
278,853
278,019
267,951
Frozen
Dinners
Coefficient (Std.)
0.0439*** (0.0037)
0.0439*** (0.0037)
0.0426*** (0.0036)
0.0426*** (0.0036)
Observations
203,191
203,191
203,064
202,953
32
Table 5. (Cont.) Category-level regressions of small price changes, synchronization
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient (Std.)
0.0317*** (0.0023)
0.0318*** (0.0023)
0.0309*** (0.0022)
0.0305*** (0.0022)
Observations
864,832
864,832
864,819
862,193
Frozen Juices
Coefficient (Std.)
0.0277*** (0.0048)
0.0279*** (0.0048)
0.0273*** (0.0046)
0.0273*** (0.0045)
Observations
308,817
308,817
308,802
298,899
Grooming
Products
Coefficient (Std.)
0.0188*** (0.0024)
0.019*** (0.0024)
0.0186*** (0.0024)
0.0186*** (0.0025)
Observations
269,873
269,872
269,780
268,124
Laundry
Detergents
Coefficient (Std.)
0.02*** (0.0033)
0.0198*** (0.0033)
0.0178*** (0.0032)
0.0176*** (0.0033)
Observations
272,765
272,765
272,695
269,543
Oatmeal
Coefficient (Std.)
0.0281*** (0.0079)
0.0281*** (0.008)
0.0282*** (0.0079)
0.0255*** (0.0081)
Observations
79,983
79,983
78,341
71,261
Paper Towels
Coefficient (Std.)
0.0447*** (0.0104)
0.0447*** (0.0104)
0.0436*** (0.0103)
0.048*** (0.0109)
Observations
116,204
116,204
115,754
108,011
Refrigerated
Juices
Coefficient (Std.)
0.035*** (0.0046)
0.0352*** (0.0046)
0.0335*** (0.0044)
0.0344*** (0.0043)
Observations
306,865
306,865
306,841
293,807
Shampoos
Coefficient (Std.)
0.0146*** (0.0016)
0.0138*** (0.0016)
0.0128*** (0.0016)
0.0127*** (0.0016)
Observations
261,778
261,778
261,740
257,886
Snack
Crackers
Coefficient (Std.)
0.0338*** (0.0032)
0.0335*** (0.0032)
0.0328*** (0.0031)
0.0328*** (0.003)
Observations
398,665
398,665
398,573
389,240
Soaps
Coefficient (Std.)
0.0375*** (0.0056)
0.0372*** (0.0055)
0.0348*** (0.0055)
0.0345*** (0.0056)
Observations
152,379
152,379
152,104
149,407
Soft Drinks
Coefficient (Std.)
0.02*** (0.0019)
0.0197*** (0.0019)
0.0199*** (0.0019)
0.02*** (0.0019)
Observations
1,350,618
1,350,617
1,350,613
1,337,747
Toothbrushes
Coefficient (Std.)
0.023*** (0.0028)
0.0219*** (0.0028)
0.0204*** (0.003)
0.0205*** (0.0029)
Observations
125,380
125,380
124,743
122,787
Toothpastes
Coefficient (Std.)
0.0112*** (0.0026)
0.0093*** (0.0026)
0.0062** (0.0026)
0.0067*** (0.0026)
Observations
264,317
264,317
264,156
260,282
Average coefficients
0.0261
0.0259
0.0249
0.0253
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 10¢, and 0 otherwise. The main independent variable is the log of the average sales volume of product i in
store s over the sample period. Column 1 reports the results of a regression that includes the log of average sales
volume and the average number of products offered in the category by the same producer. In column 2, we add the
percentage of the products whose prices changed in the same week, excluding the current observation. In column 3,
we add the average size of contemporaneous price changes, excluding the current observation. In column 4, we add
the percentage of the products that are produced by the same producer and that changed price in the same week,
excluding the current observation. All regressions include fixed effects for months, years, stores, and products. We
estimate separate regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p
< 1%
33
Figure 1. Frequency of small price changes by sales volume deciles
Notes: The chart was obtained by merging all 29 product categories and dividing the resulting data into deciles
according to the products’ sales volume. The % of small price changes
( ¢0 )1P
was calculated for each decile
as a ratio of the number of small price changes to the number of total price changes in each decile.
34
Figure 2. Frequency of price changes by size for high, medium, and low sales volume
products
35
Figure 2. (Cont.)
Notes: For each category, the figure shows the frequency of price changes for each size of price change from 1¢ to
50¢, comparing high sales volume products to medium sales volume products, and low sales volume products. To
obtain the figures, we compute the average sales volume over the entire sample period for each product, in each
store. We then group the products into high, medium, and low sales volume products. High (low) sales volume
products are products in the high (low) third of the distribution. Medium sales volume products are in the middle
third of the distribution. The y-axis shows the frequency of price changes. The red dashed line depicts the frequency
of price changes for the high sales-volume products, the purple dotted line depicts the frequency of price changes
for the medium sales-volume products, and the blue solid line depicts the frequency of price changes for the low
sales volume products. The green shaded area marks the range of small price changes,
10¢P
.
36
Figure 3. Product-level correlations between sales volume and small price changes in
the Bathroom Tissues Category
Note: The figure depicts the correlation between average sales volume (x-axis) and the percentage of small price
changes for various products in the bathroom tissues category. Each dot in the figures represents the data for the
product in a specific store. There are 93 dots in each figure, one for each store. The straight lines in the figures are
the regression lines. Black solid regression lines indicate that the regression coefficient is significant at the 5%
significance level, which is the case for 8 of the 13 products. The regression lines that are not statistically significant
are marked with red dotted lines.
1
Online Supplementary Web Appendix
Not for Publication
Small Price Changes, Sales Volume, and Menu Cost
Doron Sayag
Department of Economics, Bar-Ilan University
Ramat-Gan 5290002, Israel
DoronSayag2@gmail.com
Avichai Snir
Department of Economics, Bar-Ilan University
Ramat-Gan 5290002, Israel
snirav@biu.ac.il
Daniel Levy
Department of Economics, Bar-Ilan University
Ramat-Gan 5290002, Israel,
Department of Economics, Emory University
Atlanta, GA 30322, USA,
ICEA, ISET at TSU (Georgia), and RCEA
Daniel.Levy@biu.ac.il
Revised: February 29, 2024
2
Table of Contents
Appendix A. Controlling for measurement errors 3
Appendix B. Alternative definitions of small price changes 10
Appendix C. Using all price changes 34
Appendix D. Using a rolling 52-week window to calculate the average 41
sales volume
Appendix E. Adding Dominick’s pricing zones 45
Appendix F. Robustness of the Product-level regressions of the % of small 49
price changes and sales volume
Appendix G. Robustness: sales volume, revenue, and small price changes 55
Appendix H. Producers’ size and the robustness of the correlation 64
between small price changes and sales volumes
Appendix I. Results of cross-category analysis 71
Appendix J. Sales volume, markup, and small price changes 80
Appendix K. Category level correlation between sales volumes and the 83
size of price changes
Appendix L. Frequency of price changes by size for high, medium, and 86
low sales volume products – in percentage terms
Appendix M. National brand vs. private label products 90
Appendix N. Sales volumes, small price changes, and holidays 103
Appendix O. The likelihood of a price change, irrespective of its size 108
Appendix P. Controlling for peak days 114
Appendix Q. Estimation using only data on products what are sold in 120
single units
Appendix R. Storable vs. non-storable products 124
Appendix S. The correlation between the sales volume and the 127
likelihood of price increases vs. decreases
References 134
3
Appendix A. Controlling for measurement errors
We use a scanner dataset. As Eichenbaum et al. (2014) note, the distribution of the
size of price changes in scanner datasets is prone to measurement errors. The errors may
arise because, in scanner datasets, the price of a product in a given week is calculated as
the ratio of the sales revenue to the quantity sold. Thus, if the price has changed during
the week, or if some consumers used coupons, the price in the dataset might differ from
the actual transaction price in that week.
This type of error is less of a concern in Dominick’s dataset, because prices at
Dominick’s are set on a weekly basis, and the use of coupons in the period we study was
limited. See Barsky et al. (2003), Chen et al. (2008), and Levy et al. (2010, 2011).
Nevertheless, to mitigate possible concerns, we use in the paper only those price change
observations after which the price has remained unchanged for at least 2 weeks. If a price
remains unchanged for more than one week, then it is unlikely to be a mistake, since it is
unlikely that the same error occurred two weeks in a row.
In this appendix, we conduct two more robustness checks. First, Table A1
presents the results of regressions equivalent to the regressions we present in Table 3 in
the paper. This time, however, we include all price changes but exclude price changes
smaller or equal to 2¢. Eichenbaum et al. (2014) suggest that such small price changes
could be the result of measurement errors. Alvarez et al. (2016) also use Dominick’s data,
and they remove observations on price changes of 1¢. We, therefore, are more
conservative by using a stricter rule than Alvarez et al. (2016). The regressions take the
following form:
, , , , ,
,,
ln( )
i s t i s i s t
t t s i i s t
small price change average sales volume
month year u
X
(A1)
where small price change is a dummy that equals 1 if a price change of product i in store
s at time t is less or equal to 10¢ and larger than 2¢, and 0 otherwise. The average sales
volume is the average sales volume of product i in store s over the sample period. X is a
matrix of other control variables. Month and year are fixed effects for the month and the
year of the price change.
and
are fixed effects for stores and products. u is an i.i.d
error term. We estimate separate regressions for each product category, clustering the
4
errors by product.
The values in Table A1 are the coefficients of the log of the average sales volume. In
column 1, the only control variables are the log of the average sales volume, and the
dummies for months, years, stores, and products. Consistent with the results we report in
the paper, we find that all the coefficients of the log of the average sales volume are
positive. 28 of the 29 coefficients are statistically significant. The average coefficient is
0.030, suggesting that a 1% increase in the sales volume is associated with a 3% increase
in the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and for sale- and bounce-back prices, which we identify
using the sales filter algorithm of Fox and Syed (2016). All the coefficients are positive
and statistically significant: 26 at the 1% level, two at the 5% level, and one at the 10%
level. The average coefficient is 0.025, suggesting that a 1% increase in the sales volume
is associated with a 2.5% increase in the likelihood of a small price change.
In column 3, we also add control for 9-ending prices. All coefficients remain
positive and statistically significant: 26 at the 1% level, one at the 5%, and two at the
10% level. The average coefficient is 0.023, suggesting that a 1% increase in the sales
volume is associated with a 2.3% increase in the likelihood of a small price change.
As a further control for the possible effects of sales on the results, in column 4 we
focus on regular prices by excluding all sale- and bounce-back prices. When we focus on
regular prices, the results are even stronger. All the coefficients are positive and
statistically significant at the 1% level. The average coefficient is 0.045, suggesting that a
1% increase in the sales volume is associated with a 4.5% increase in the likelihood of a
small price change.
As a second robustness test, we re-run the above regressions, after dropping
observations if Dominick’s sales flag indicated that there was a coupon use in either the
week the price changed or in the preceding week because according to Eichenbaum et al.
(2014), that might lead to spurious small price changes.
Table A2 reports the estimation results. The coefficient estimates are similar in
sign, magnitude, and statistical significance, to the corresponding figures in Table A1. In
all columns, the coefficient estimates are positive and significant, ranging between 0.025
5
and 0.046, on average.
To summarize, the exclusion of (a) very small price changes, or (b) the exclusion of
observations with coupon use, do not change our main result. The likelihood of small
price changes remains strongly correlated with the average sales volume. We, therefore,
conclude that our results are not likely to be driven by measurement errors.
6
Table A1. Category-level regressions of small price changes
(0¢)1P
and sales volume
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0343***
(0.0031)
0.0271***
(0.0026)
0.0224***
(0.0025)
0.044***
(0.0057)
Observations
275,225
275,225
275,225
73,576
Bath Soap
Coefficient
(Std.)
0.0396***
(0.0085)
0.044***
(0.0088)
0.0417***
(0.0086)
0.0897***
(0.0162)
Observations
35,377
35,377
35,377
6,362
Bathroom
Tissues
Coefficient
(Std.)
0.0311***
(0.0051)
0.019***
(0.0055)
0.0165***
(0.0052)
0.04***
(0.0071)
Observations
288,963
288,963
288,963
58,189
Beer
Coefficient
(Std.)
0.0212***
(0.0013)
0.023***
(0.0011)
0.0198***
(0.001)
0.0673***
(0.005)
Observations
456,740
456,740
456,740
54,870
Bottled Juice
Coefficient
(Std.)
0.0457***
(0.0042)
0.0343***
(0.0031)
0.0304***
(0.0032)
0.0395***
(0.0049)
Observations
881,264
881,264
881,264
188,079
Canned Soup
Coefficient
(Std.)
0.0202***
(0.0041)
0.0109***
(0.0037)
0.0121***
(0.0036)
0.0268***
(0.0051)
Observations
814,575
814,575
814,575
191,616
Canned Tuna
Coefficient
(Std.)
0.0322***
(0.0051)
0.0246***
(0.0045)
0.0216***
(0.0043)
0.0361***
(0.0057)
Observations
330,897
330,897
330,897
89,246
Cereals
Coefficient
(Std.)
0.0177***
(0.0025)
0.0144***
(0.0023)
0.0135***
(0.0024)
0.0251***
(0.0038)
Observations
685,899
685,899
685,899
227,390
Cheese
Coefficient
(Std.)
0.0301***
(0.0029)
0.0189***
(0.0024)
0.0159***
(0.0024)
0.0123***
(0.0044)
Observations
1,615,593
1,615,593
1,615,593
371,129
Cigarettes
Coefficient
(Std.)
0.0131
(0.0081)
0.0144*
(0.0071)
0.014*
(0.007)
0.0148***
(0.005)
Observations
15,395
15,395
15,395
9,130
Cookies
Coefficient
(Std.)
0.0348***
(0.0016)
0.0317***
(0.0016)
0.0273***
(0.0015)
0.05***
(0.0031)
Observations
1,305,448
1,305,448
1,305,448
205,310
Crackers
Coefficient
(Std.)
0.044***
(0.0029)
0.0365***
(0.0027)
0.0334***
(0.0026)
0.0516***
(0.0052)
Observations
453,298
453,298
453,298
78,127
Dish
Detergent
Coefficient
(Std.)
0.0377***
(0.0037)
0.03***
(0.003)
0.0273***
(0.0029)
0.04***
(0.0047)
Observations
374,089
374,089
374,089
76,206
Fabric
Softener
Coefficient
(Std.)
0.0246***
(0.0036)
0.0176***
(0.0033)
0.0153***
(0.0034)
0.0378***
(0.0053)
Observations
357,746
357,746
357,746
86,846
Front-End-
Candies
Coefficient
(Std.)
0.0238***
(0.0036)
0.0146***
(0.0028)
0.0139***
(0.0028)
0.0121***
(0.0033)
Observations
415,331
415,331
415,331
121,111
Frozen
Dinners
Coefficient
(Std.)
0.0457***
(0.0026)
0.0381***
(0.0025)
0.0373***
(0.0025)
0.101***
(0.0067)
Observations
477,997
477,997
477,997
57,704
7
Table A1. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0321***
(0.0016)
0.0284***
(0.0015)
0.0279***
(0.0015)
0.0572***
(0.0034)
Observations
1,768,979
1,768,979
1,768,979
295,796
Frozen Juices
Coefficient
(Std.)
0.0262***
(0.0036)
0.0216***
(0.0033)
0.0196***
(0.0032)
0.0308***
(0.0059)
Observations
602,210
602,210
602,210
112,532
Grooming
Products
Coefficient
(Std.)
0.0394***
(0.0022)
0.0426***
(0.002)
0.0379***
(0.002)
0.0637***
(0.0061)
Observations
658,707
658,707
658,707
95,757
Laundry
Detergents
Coefficient
(Std.)
0.0156***
(0.0029)
0.0133***
(0.0025)
0.0112***
(0.0023)
0.025***
(0.0047)
Observations
580,679
580,679
580,679
135,575
Oatmeal
Coefficient
(Std.)
0.0241***
(0.007)
0.0153**
(0.0059)
0.0139***
(0.0059)
0.0416***
(0.0073)
Observations
154,817
154,817
154,817
51,510
Paper Towels
Coefficient
(Std.)
0.0306***
(0.0119)
0.0255**
(0.0125)
0.0245*
(0.0127)
0.0359***
(0.0119)
Observations
215,951
215,951
215,951
36,645
Refrigerated
Juices
Coefficient
(Std.)
0.0239***
(0.0032)
0.0179***
(0.0028)
0.0158***
(0.0027)
0.029***
(0.0047)
Observations
749,239
749,239
749,239
127,091
Shampoos
Coefficient
(Std.)
0.0293***
(0.0013)
0.0337***
(0.0013)
0.0295***
(0.0012)
0.0644***
(0.0042)
Observations
708,002
708,002
708,002
83,652
Snack
Crackers
Coefficient
(Std.)
0.0365***
(0.0029)
0.0338***
(0.0028)
0.0305***
(0.0026)
0.0621***
(0.0041)
Observations
770,442
770,442
770,442
127,881
Soaps
Coefficient
(Std.)
0.0231***
(0.0011)
0.0205***
(0.0009)
0.0171***
(0.0008)
0.0442***
(0.0023)
Observations
4,243,492
4,243,492
4,243,492
305,545
Soft Drinks
Coefficient
(Std.)
0.0415***
(0.0058)
0.0342***
(0.0042)
0.0286***
(0.004)
0.0562***
(0.0069)
Observations
300,763
300,763
300,763
71,459
Toothbrushes
Coefficient
(Std.)
0.0248***
(0.0029)
0.0276***
(0.003)
0.0237***
(0.0029)
0.0562***
(0.0059)
Observations
291,093
291,093
291,093
42,658
Toothpastes
Coefficient
(Std.)
0.0242***
(0.0029)
0.0247***
(0.0025)
0.0218***
(0.0024)
0.0507***
(0.0059)
Observations
584,401
584,401
584,401
84,802
Average coefficients
0.0299
0.0255
0.0229
0.0450
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 10¢ and larger than 2¢, and 0 otherwise. The main independent variable is the log of the average sales
volume of product i in store s over the sample period. Column 1 reports the results of the baseline regression that
includes only the log of the average sales volume and the fixed effects for months, years, stores, and products. In
column 2, we add the following controls: the natural log of the average price, the natural log of the absolute change in
the wholesale price, and control for sale- and bounce-back prices, which we identify using a sales filter algorithm. In
column 3, we add a dummy for 9-ending prices as an additional control. In column 4, we focus on regular prices by
excluding the sale- and bounce-back prices. We estimate separate regressions for each product category, clustering the
errors by product. * p < 10%, ** p < 5%, *** p < 1%
8
Table A2. Category-level regressions of small price changes and sales volume, excluding
coupon sales
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0388***
(0.0033)
0.0305***
(0.0027)
0.0248***
(0.0025)
0.0475***
(0.0057)
Observations
278,043
278,043
278,043
75,945
Bath Soap
Coefficient
(Std.)
0.0409***
(0.0093)
0.0452***
(0.0095)
0.0422***
(0.0091)
0.0871***
(0.016)
Observations
35,795
35,795
35,795
6,555
Bathroom
Tissues
Coefficient
(Std.)
0.0372***
(0.0056)
0.0203***
(0.0053)
0.0177***
(0.0049)
0.0351***
(0.0069)
Observations
326,382
326,382
326,382
81,914
Beer
Coefficient
(Std.)
0.023***
(0.0015)
0.0249***
(0.0012)
0.0208***
(0.0012)
0.0691***
(0.005)
Observations
459,669
459,669
459,669
56,427
Bottled Juice
Coefficient
(Std.)
0.0554***
(0.0043)
0.0393***
(0.003)
0.0343***
(0.0031)
0.0368***
(0.0045)
Observations
959,958
959,958
959,958
244,198
Canned Soup
Coefficient
(Std.)
0.0272***
(0.004)
0.0151***
(0.0034)
0.0158***
(0.0033)
0.0217***
(0.0038)
Observations
947,633
947,633
947,633
278,451
Canned Tuna
Coefficient
(Std.)
0.037***
(0.0052)
0.0266***
(0.0044)
0.0225***
(0.0041)
0.0334***
(0.0047)
Observations
375,343
375,343
375,343
116,170
Cereals
Coefficient
(Std.)
0.0216***
(0.0026)
0.0168***
(0.0023)
0.0156***
(0.0024)
0.0263***
(0.0035)
Observations
724,232
724,232
724,232
260,035
Cheese
Coefficient
(Std.)
0.0374***
(0.0029)
0.0208***
(0.0022)
0.0168***
(0.0022)
0.0116***
(0.0031)
Observations
1,811,792
1,811,792
1,811,792
519,225
Cigarettes
Coefficient
(Std.)
0.019***
(0.0082)
0.0203***
(0.0068)
0.0197***
(0.0067)
0.0215***
(0.0045)
Observations
15,862
15,862
15,862
9,593
Cookies
Coefficient
(Std.)
0.0429***
(0.0017)
0.0372***
(0.0017)
0.0315***
(0.0015)
0.0542***
(0.0031)
Observations
1,356,845
1,356,845
1,356,845
229,139
Crackers
Coefficient
(Std.)
0.0544***
(0.0033)
0.0431***
(0.0031)
0.0389***
(0.0029)
0.0563***
(0.0061)
Observations
475,368
475,368
475,368
89,210
Dish
Detergent
Coefficient
(Std.)
0.0481***
(0.0038)
0.0357***
(0.003)
0.0315***
(0.0029)
0.0417***
(0.0043)
Observations
401,001
401,001
401,001
95,477
Fabric
Softener
Coefficient
(Std.)
0.0342***
(0.0038)
0.0245***
(0.0034)
0.0209***
(0.0035)
0.0428***
(0.0049)
Observations
378,773
378,773
378,773
101,926
Front-End-
Candies
Coefficient
(Std.)
0.0165***
(0.0039)
0.0091***
(0.0028)
0.0082***
(0.0028)
0.0113***
(0.0031)
Observations
490,220
490,220
490,220
155,203
Frozen
Dinners
Coefficient
(Std.)
0.0536***
(0.0027)
0.0408***
(0.0025)
0.0394***
(0.0025)
0.0907***
(0.006)
Observations
502,792
502,792
502,792
72,693
9
Table A2. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0354***
(0.0019)
0.0301***
(0.0017)
0.0292***
(0.0017)
0.0602***
(0.0032)
Observations
1,848,166
1,848,166
1,848,166
353,120
Frozen Juices
Coefficient
(Std.)
0.0342***
(0.0037)
0.0253***
(0.0031)
0.0227***
(0.003)
0.03***
(0.0048)
Observations
659,295
659,295
659,295
150,129
Grooming
Products
Coefficient
(Std.)
0.0426***
(0.0024)
0.0455***
(0.0022)
0.039***
(0.0021)
0.0673***
(0.0061)
Observations
668,809
668,809
668,809
99,252
Laundry
Detergents
Coefficient
(Std.)
0.0185***
(0.0031)
0.0155***
(0.0027)
0.0126***
(0.0025)
0.0264***
(0.0047)
Observations
594,247
594,247
594,247
145,167
Oatmeal
Coefficient
(Std.)
0.0288***
(0.0071)
0.0172***
(0.0052)
0.0151***
(0.0052)
0.0319***
(0.0094)
Observations
168,988
168,988
168,988
63,575
Paper Towels
Coefficient
(Std.)
0.0376***
(0.0114)
0.0296***
(0.0116)
0.0284***
(0.0117)
0.0376***
(0.0096)
Observations
244,037
244,037
244,037
52,321
Refrigerated
Juices
Coefficient
(Std.)
0.031***
(0.0032)
0.0209***
(0.0027)
0.0182***
(0.0026)
0.0305***
(0.0041)
Observations
800,176
800,176
800,176
161,074
Shampoos
Coefficient
(Std.)
0.0323***
(0.0014)
0.0368***
(0.0014)
0.032***
(0.0013)
0.0674***
(0.0043)
Observations
713,652
713,652
713,652
86,458
Snack
Crackers
Coefficient
(Std.)
0.0435***
(0.0032)
0.0382***
(0.003)
0.0338***
(0.0027)
0.066***
(0.004)
Observations
801,599
801,599
801,599
143,154
Soaps
Coefficient
(Std.)
0.0306***
(0.0014)
0.0265***
(0.001)
0.0223***
(0.0009)
0.0586***
(0.0027)
Observations
4,372,346
4,372,346
4,372,346
346,106
Soft Drinks
Coefficient
(Std.)
0.0545***
(0.006)
0.0413***
(0.0044)
0.0336***
(0.0042)
0.0555***
(0.0057)
Observations
333,170
333,170
333,170
94,295
Toothbrushes
Coefficient
(Std.)
0.0291***
(0.0032)
0.0317***
(0.0034)
0.0265***
(0.0032)
0.0618***
(0.006)
Observations
295,275
295,275
295,275
44,690
Toothpastes
Coefficient
(Std.)
0.0289***
(0.0032)
0.028***
(0.0027)
0.0241***
(0.0026)
0.0561***
(0.0063)
Observations
596,900
596,900
596,900
91,759
Average coefficients
0.0356
0.0288
0.0254
0.0461
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 10¢, and 0 otherwise. We exclude observations on price changes if Dominick’s sales flag indicates a coupon
sale in either week t or t − 1. The main independent variable is the log of the average sales volume of product i in store
s over the sample period. Column 1 reports the results of the baseline regression that includes only the log of the
average sales volume and fixed effects for months, years, stores, and products. In column 2, we add the following
controls: the natural log of the average price, the natural log of the absolute change in the wholesale price, and control
for sale- and bounce-back prices, which we identify using a sales filter algorithm. In column 3, we add a dummy for
9-ending prices as an additional control. In column 4, we focus on regular prices by excluding the sale- and bounce-
back prices. We estimate separate regressions for each product category, clustering the errors by product. * p < 10%,
** p < 5%, *** p < 1%
10
Appendix B. Alternative definitions of small price changes
In the paper, we define a small price change as a price change smaller than or equal
to 10¢. In this appendix, we repeat our main analyses using 8 alternative definitions of
small price changes. First, we define small price changes as (1) price changes up to, and
including, 5¢, (2) price changes up to, and including, 15¢, (3) price changes up to, and
including 2%, and (4) price changes up to, and including, 5%.
Second, we follow Midrigan (2011) and Bhattarai and Schoenle (2014) to define
small price changes relative to the average price change in the corresponding category.
I.e., a price change is small if it is smaller than or equal to
, where
is the
average price change of product in store , and attains the values 0.5, 0.33, 0.25 and
0.10.
As we do in the paper, we use observations on price changes only if we observe the
price in both weeks t and t + 1 and the post-change price remained unchanged for at least
2 weeks.
Table B1 presents the results of regressions equivalent to the regressions in Table 3
in the paper. The regressions take the following form:
, , , , ,
,,
ln( )
i s t i s i s t
t t s i i s t
small price change average sales volume
month year u
X
(B1)
where small price change is a dummy that equals 1 if a price change of product i in store
s at time t is less or equal to 5¢, and 0 otherwise. The average sales volume is the average
sales volume of product i in store s over the sample period. X is a matrix of other control
variables. Month and year are fixed effects for the month and the year of the price
change.
and
are fixed effects for stores and products, respectively, and u is an i.i.d
error term. We estimate separate regressions for each product category, clustering the
errors by product.
The values in the table are the coefficients of the log of the average sales volume. In
column 1, the only control variables are the log of the average sales volume, and the
dummies for months, years, stores, and products. We find that 28 of the coefficients of
the log of the average sales volume are positive, 16 of them are statistically significant.
The average coefficient is 0.010, suggesting that a 1% increase in the sales volume is
11
associated with a 1.0% increase in the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). 27 of the coefficients are
positive, 13 of the 27 are statistically significant, and 2 more are marginally statistically
significant. The average coefficient is 0.007, suggesting that a 1% increase in the sales
volume is associated with a 0.7% increase in the likelihood of a small price change.
In column 3, we also add control for 9-ending prices. 27 of the coefficients are
positive, 14 of them statistically significant, and 3 more are marginally statistically
significant. The average coefficient is 0.008, suggesting that a 1% increase in the sales
volume is associated with a 0.8% increase in the likelihood of a small price change.
As a further control for the effects of sales on the results, in column 4 we focus on
regular prices by excluding all sale- and bounce-back prices. We find that 28 coefficients
are positive. 20 of the positive coefficients are statistically significant, and 2 more are
statistically significant at the 10% level. The average coefficient is 0.019, suggesting that
a 1% increase in the sales volume is associated with a 1.9% increase in the likelihood of a
small price change.
Table B2 presents the results of similar regressions, where we define small price
changes as price changes of up to, and including, 15¢. In column 1, the only control
variables are the log of the average sales volume, and the dummies for months, years,
stores, and products. We find that 26 of the coefficients of the log of the average sales
volume are positive. 17 of the 26 are statistically significant, and 2 more are marginally
statistically significant. The average coefficient is 0.016, suggesting that a 1% increase in
the sales volume is associated with a 1.6% increase in the likelihood of a small price
change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). 25 of the coefficients are
positive. 13 of the positive coefficients are statistically significant, and 2 more are
marginally statistically significant. The average coefficient is 0.012, suggesting that a 1%
increase in the sales volume is associated with a 1.2% increase in the likelihood of a
12
small price change.
In column 3, we also add control for 9-ending prices. 25 of the coefficients are
positive. 13 of the positive coefficients are statistically significant, and 5 more are
marginally statistically significant. The average coefficient is 0.012, suggesting that a 1%
increase in the sales volume is associated with a 1.2% increase in the likelihood of a
small price change.
As a further control for the effects of sales on the results, in column 4 we focus on
regular prices by excluding all sale- and bounce-back prices. 26 of the coefficients are
positive. 17 of the 26 are statistically significant, and 2 more are statistically significant at
the 10% level. The average coefficient is 0.019, suggesting that a 1% increase in the sales
volume is associated with a 1.9% increase in the likelihood of a small price change.
Table B3 presents the results where we define small price changes as price changes
of up to 2%. In column 1, the only control variables are the log of the average sales
volume, and the dummies for months, years, stores, and products. We find that 27 of the
29 coefficients of the log of the average sales volume are positive. Out of the 27, 20 are
statistically significant, and 3 more are statistically significant at the 10% level. The
average coefficient is 0.009, suggesting that a 1% increase in the sales volume is
associated with a 0.9% increase in the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). We find that 27 of the 29
coefficients are positive. 17 of the 27 are statistically significant, and 6 more are
statistically significant at the 10% level. The average coefficient is 0.007, suggesting that
a 1% increase in the sales volume is associated with a 0.7% increase in the likelihood of a
small price change.
In column 3, we also add a control for 9-ending prices. 27 of the 29 coefficients are
still positive. 17 of the 27 are statistically significant, and 5 more are statistically
significant at the 10% level. The average coefficient is 0.007, suggesting that a 1%
increase in the sales volume is associated with a 0.7% increase in the likelihood of a
small price change.
As a further control for the effects of sales on the results, in column 4 we focus on
13
regular prices by excluding all sale- and bounce-back prices. When we focus on regular
prices, 28 of the 29 coefficients are positive. 17 of the positive coefficients are
statistically significant, and 3 more are marginally statistically significant. The average
coefficient is 0.015, suggesting that a 1% increase in the sales volume is associated with a
1.5% increase in the likelihood of a small price change.
Table B4 presents the results where we define small price changes as price changes
up to 5%. In column 1, the only control variables are the log of the average sales volume,
and the dummies for months, years, stores, and products. We find that 23 coefficients of
the log of the average sales volume are positive. 17 of them are statistically significant,
and 2 more are marginally statistically significant. The average coefficient is 0.015,
suggesting that a 1% increase in the sales volume is associated with a 1.5% increase in
the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). 23 of the coefficients are
positive. 15 of the positive coefficients are statistically significant, and 2 more are
marginally statistically significant. The average coefficient is 0.010, suggesting that a 1%
increase in the sales volume is associated with a 1.0% increase in the likelihood of a
small price change.
In column 3, we also add a control for 9-ending prices. 23 of the coefficients are
positive. 15 of the 23 are statistically significant, and 2 more are marginally statistically
significant. The average coefficient is 0.010, suggesting that a 1% increase in the sales
volume is associated with a 1.0% increase in the likelihood of a small price change.
As a further control for the effects of sales on the results, in column 4 we focus on
regular prices by excluding all sale- and bounce-back prices. When we focus on regular
prices, 28 of the coefficients are positive. 16 of the 28 are statistically significant, and 2
more are marginally statistically significant. The average coefficient is 0.021, suggesting
that a 1% increase in the sales volume is associated with a 2.1% increase in the likelihood
of a small price change.
Table B5 presents the results where we define small price changes as price changes
of up to 50% of the average price change of the product-store. In other words, a price
14
change, , of product in store in week is small if
, where
is the average size of a price change of product in store . In column 1, the only
control variables are the log of the average sales volume, and dummies for months, years,
stores, and products. We find that 26 of the coefficients are positive. 22 of the positive
coefficients are statistically significant, and 1 more is marginally statistically significant.
The average coefficient is 0.021, suggesting that a 1% increase in the sales volume is
associated with a 2.1% increase in the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). We find that 26 of the
coefficients are positive. 18 of the 26 are statistically significant, and 2 more are
marginally statistically significant. The average coefficient is 0.020, suggesting that a 1%
increase in the sales volume is associated with a 2.0% increase in the likelihood of a
small price change.
In column 3, we also add a control for 9-ending prices. We find that 27 of the
coefficients are positive. 18 of the 27 are statistically significant, and 2 more are
marginally statistically significant. The average coefficient is 0.020, suggesting that a 1%
increase in the sales volume is associated with a 2.0% increase in the likelihood of a
small price change.
As a further control for the effects of sales on the results, in column 4 we focus on
regular prices by excluding all sale- and bounce-back prices. When we focus on regular
prices, 28 of the 29 are statistically significant. 23 of the positive coefficients are
statistically significant, and 3 more are marginally significant. The average coefficient is
0.041, suggesting that a 1% increase in the sales volume is associated with a 4.1%
increase in the likelihood of a small price change.
Table B6 presents the results where we define small price changes as price changes
up to 33% of the average price in the category. In other words, a price change, , of
product in store in week is small if
where
is the average
size of a price change of product in store . In column 1, the only control variables are
the log of the average sales volume, and dummies for months, years, stores, and products.
We find that 27 of the 29 coefficients of the log of the average sales volume are positive.
15
22 of them are statistically significant, and 2 more is marginally significant. The average
coefficient is 0.016, suggesting that a 1% increase in the sales volume is associated with a
1.6% increase in the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). We find that 27 of the 29
coefficients are positive. 18 of them are statistically significant, and 3 more are
marginally significant. The average coefficient is 0.015, suggesting that a 1% increase in
the sales volume is associated with a 1.5% increase in the likelihood of a small price
change.
In column 3, we also add a control for 9-ending prices. We find that 27 of the 29
coefficients are positive. 18 of them are statistically significant, and 3 more are
marginally significant. The average coefficient is 0.015, suggesting that a 1% increase in
the sales volume is associated with a 1.5% increase in the likelihood of a small price
change.
As a further control for the effects of sales on the results, in column 4 we focus on
regular prices by excluding all sale- and bounce-back prices. We find that all the
coefficients are positive and 23 of them are statistically significant. 3 more coefficients
are marginally significant. The average coefficient is 0.031, suggesting that a 1% increase
in the sales volume is associated with a 3.1% increase in the likelihood of a small price
change.
Table B7 presents the results where we define small price changes as price changes
up to 25% of the average price in the category. In other words, a price change, , of
product in store in week is small if
, where
is the average
size of a price change of product in store . In column 1, the only control variables are
the log of the average sales volume, and the dummies for months, years, stores, and
products. We find that 28 of the 29 coefficients of the log of the average sales volume are
positive. 22 of them are statistically significant, and 1 more is marginally significant. The
average coefficient is 0.013, suggesting that a 1% increase in the sales volume is
associated with a 1.3% increase in the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
16
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). We find that 27 of the 29
coefficients are positive. 22 of them are statistically significant. The average coefficient is
0.012, suggesting that a 1% increase in the sales volume is associated with a 1.2%
increase in the likelihood of a small price change.
In column 3, we also add a control for 9-ending prices. We find that 27 of the 29
coefficients are positive. 22 of them are statistically significant. The average coefficient is
0.012, suggesting that a 1% increase in the sales volume is associated with a 1.2%
increase in the likelihood of a small price change.
As a further control for the effects of sales on the results, in column 4 we focus on
regular prices by excluding all sale- and bounce-back prices. We find that all the
coefficients are positive and 25 of them are statistically significant at the 1% level. One
more coefficient is marginally significant. The average coefficient is 0.025, suggesting
that a 1% increase in the sales volume is associated with a 2.5% increase in the likelihood
of a small price change.
Table B8 presents the results where we define small price changes as price changes
up to 10% of the average price in the category. In other words, a price change, , of
product in store in week is small if
, where
is the average
size of a price change of product in store . In column 1, the only control variables are
the log of the average sales volume, and the dummies for months, years, stores, and
products. We find that 24 of the 29 coefficients of the log of the average sales volume are
positive. 19 of them are statistically significant, and 2 more are marginally significant.
The average coefficient is 0.004, suggesting that a 1% increase in the sales volume is
associated with a 0.4% increase in the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). We find that 25 of the 29
coefficients are positive. 20 of them are statistically significant, and 2 more are
marginally significant. The average coefficient is 0.005, suggesting that a 1% increase in
the sales volume is associated with a 0.5% increase in the likelihood of a small price
change.
17
In column 3, we also add a control for 9-ending prices. We find that 25 of the 29
coefficients are positive. 20 of them are statistically significant, and 2 more are
marginally significant. The average coefficient is 0.005, suggesting that a 1% increase in
the sales volume is associated with a 0.5% increase in the likelihood of a small price
change.
As a further control for the effects of sales on the results, in column 4 we focus on
regular prices by excluding all sale- and bounce-back prices. We find that 25 of the
coefficients are positive. 20 of them are statistically significant, and 3 more are
marginally significant. The average coefficient is 0.010, suggesting that a 1% increase in
the sales volume is associated with a 1.0% increase in the likelihood of a small price
change.
18
Table B1. Category-level regressions of small price changes
(5¢)P
and sales volume
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0033
(0.0023)
0.0022
(0.0022)
0.0019
(0.0022)
0.0068
(0.0056)
Observations
74,451
74,451
74,451
24,729
Bath Soap
Coefficient
(Std.)
0.0128**
(0.0053)
0.0114**
(0.0051)
0.0113**
(0.0044)
0.0198
(0.0129)
Observations
6,650
6,650
6,650
1,466
Bathroom
Tissues
Coefficient
(Std.)
0.0481***
(0.0079)
0.0235***
(0.0066)
0.0233***
(0.0063)
0.0466***
(0.0074)
Observations
56,458
56,458
56,458
19,285
Beer
Coefficient
(Std.)
0.0003
(0.0002)
0.0005**
(0.0002)
0.0005**
(0.0002)
0.0051**
(0.0021)
Observations
187,691
187,691
187,691
12,080
Bottled Juice
Coefficient
(Std.)
0.0067
(0.0068)
0.0017
(0.0059)
0.0017
(0.006)
0.0398***
(0.0079)
Observations
224,857
224,857
224,857
60,015
Canned Soup
Coefficient
(Std.)
0.0055
(0.0086)
0.0028
(0.0084)
0.0052
(0.0082)
0.0148*
(0.0078)
Observations
233,779
233,779
233,779
95,310
Canned Tuna
Coefficient
(Std.)
0.0097**
(0.0047)
0.004
(0.0045)
0.0039
(0.0045)
0.0201***
(0.0064)
Observations
112,629
112,629
112,629
31,922
Cereals
Coefficient
(Std.)
0.0042
(0.0036)
0.0045
(0.0034)
0.0045
(0.0033)
0.019***
(0.0059)
Observations
141,087
141,087
141,087
72,789
Cheese
Coefficient
(Std.)
0.0004
(0.0029)
-0.0001
(0.0023)
-0.0003
(0.0023)
0.018***
(0.0051)
Observations
357,679
357,679
357,679
92,758
Cigarettes
Coefficient
(Std.)
0.0114***
(0.0021)
0.0107***
(0.0021)
0.0108***
(0.0021)
0.0114***
(0.0025)
Observations
24,553
24,553
24,553
20,692
Cookies
Coefficient
(Std.)
0.0043***
(0.001)
0.0037***
(0.001)
0.0036***
(0.001)
0.0149***
(0.0026)
Observations
317,932
317,932
317,932
66,087
Crackers
Coefficient
(Std.)
0.0006
(0.0016)
0.0001
(0.0016)
0.0002
(0.0016)
0.0141***
(0.0044)
Observations
115,658
115,658
115,658
24,771
Dish
Detergent
Coefficient
(Std.)
0.0175***
(0.003)
0.0123***
(0.0026)
0.0126***
(0.0024)
0.0289***
(0.0052)
Observations
85,222
85,222
85,222
26,735
Fabric
Softener
Coefficient
(Std.)
0.01**
(0.0044)
0.0027
(0.0039)
0.0032
(0.0039)
0.0157**
(0.0079)
Observations
85,337
85,337
85,337
27,488
Front-End-
Candies
Coefficient
(Std.)
-0.0038
(0.0034)
-0.0046
(0.0031)
-0.0045
(0.0031)
0.0011
(0.0028)
Observations
148,200
148,200
148,200
77,323
Frozen
Dinners
Coefficient
(Std.)
0.0252***
(0.0061)
0.0186***
(0.0052)
0.0198***
(0.0051)
0.0524***
(0.012)
Observations
52,893
52,893
52,893
12,287
19
Table B1. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0132***
(0.0022)
0.0123***
(0.0019)
0.0125***
(0.0019)
0.0294***
(0.0028)
Observations
345,223
345,223
345,223
117,044
Frozen Juices
Coefficient
(Std.)
0.0185***
(0.0051)
0.0162***
(0.0044)
0.0168***
(0.0044)
0.0249***
(0.0073)
Observations
118,582
118,582
118,582
40,517
Grooming
Products
Coefficient
(Std.)
0.0028**
(0.0011)
0.0029***
(0.0011)
0.0031***
(0.0011)
0.0058
(0.0039)
Observations
101,944
101,944
101,944
22,102
Laundry
Detergents
Coefficient
(Std.)
0.0053**
(0.0024)
0.0024
(0.0022)
0.0027
(0.0022)
0.0073*
(0.0042)
Observations
121,566
121,566
121,566
42,121
Oatmeal
Coefficient
(Std.)
0.0421***
(0.0139)
0.0327***
(0.011)
0.0308***
(0.0104)
0.0564***
(0.0153)
Observations
25,523
25,523
25,523
13,605
Paper Towels
Coefficient
(Std.)
0.0113
(0.0101)
0.0095
(0.0097)
0.0107
(0.0095)
-0.006
(0.0108)
Observations
48,199
48,199
48,199
9,243
Refrigerated
Juices
Coefficient
(Std.)
0.018***
(0.0054)
0.0104*
(0.0057)
0.0104*
(0.0056)
0.0267**
(0.0108)
Observations
108,965
108,965
108,965
23,705
Shampoos
Coefficient
(Std.)
0.0007
(0.0006)
0.0008
(0.0006)
0.0008
(0.0006)
0.0038
(0.0023)
Observations
88,193
88,193
88,193
16,099
Snack
Crackers
Coefficient
(Std.)
0.0018
(0.0013)
0.0024*
(0.0013)
0.0025**
(0.0013)
0.0131***
(0.0034)
Observations
176,527
176,527
176,527
38,123
Soaps
Coefficient
(Std.)
0.0216***
(0.0084)
0.0125
(0.0082)
0.0157**
(0.0079)
0.0473***
(0.0109)
Observations
56,725
56,725
56,725
16,882
Soft Drinks
Coefficient
(Std.)
0.0026
(0.0018)
0.006***
(0.0015)
0.0048***
(0.0015)
0.0005
(0.0027)
Observations
243,837
243,837
243,837
49,989
Toothbrushes
Coefficient
(Std.)
0.0066**
(0.0026)
0.0059**
(0.0026)
0.0057**
(0.0025)
0.0121**
(0.0059)
Observations
52,185
52,185
52,185
13,695
Toothpastes
Coefficient
(Std.)
0.0036
(0.0026)
0.0036
(0.0023)
0.0038*
(0.0022)
0.0145***
(0.0055)
Observations
100,845
100,845
100,845
28,039
Average coefficients
0.0105
0.0073
0.0075
0.0195
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 5¢, and 0 otherwise. The main independent variable is the log of the average sales volume of product i in
store s over the sample period. Column 1 reports the results of the baseline regression that includes only the log of the
average sales volume and the fixed effects for months, years, stores, and products. In column 2, we add the following
controls: the log of the average price, the log of the absolute change in the wholesale price, and a control for sale- and
bounce-back prices, which we identify using a sales filter algorithm. In column 3, we add a dummy for 9-ending prices
as an additional control. In column 4, we focus on regular prices by excluding the sale- and bounce-back prices. We
estimate separate regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p
< 1%
20
Table B2. Category-level regressions of small price changes
(5¢)1P
and sales volume
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0177***
(0.0052)
0.0127***
(0.0049)
0.0118***
(0.0049)
0.0078*
(0.0091)
Observations
74,451
74,451
74,451
24,729
Bath Soap
Coefficient
(Std.)
0.0349**
(0.0189)
0.0296**
(0.0179)
0.0295**
(0.0177)
0.018
(0.0348)
Observations
6,650
6,650
6,650
1,466
Bathroom
Tissues
Coefficient
(Std.)
0.0592***
(0.01)
0.0333***
(0.0092)
0.0332***
(0.0094)
0.0323***
(0.0084)
Observations
56,458
56,458
56,458
19,285
Beer
Coefficient
(Std.)
0.0018***
(0.0006)
0.0042***
(0.0007)
0.0042***
(0.0007)
0.0219***
(0.0052)
Observations
187,691
187,691
187,691
12,080
Bottled Juice
Coefficient
(Std.)
0.015***
(0.0069)
0.0108**
(0.006)
0.0109**
(0.0058)
0.0161**
(0.0088)
Observations
224,857
224,857
224,857
60,015
Canned Soup
Coefficient
(Std.)
-0.0049*
(0.0056)
-0.0057*
(0.0056)
-0.0044
(0.0054)
0.0009
(0.0035)
Observations
233,779
233,779
233,779
95,310
Canned Tuna
Coefficient
(Std.)
0.0084*
(0.0077)
-0.0021
(0.0066)
-0.0022
(0.0066)
0.0098*
(0.0077)
Observations
112,629
112,629
112,629
31,922
Cereals
Coefficient
(Std.)
0.0054*
(0.0058)
0.0052*
(0.0053)
0.0052*
(0.0053)
0.0071*
(0.0061)
Observations
141,087
141,087
141,087
72,789
Cheese
Coefficient
(Std.)
0.0055**
(0.0042)
0.0052**
(0.0037)
0.0052**
(0.0037)
0.0104***
(0.0039)
Observations
357,679
357,679
357,679
92,758
Cigarettes
Coefficient
(Std.)
0.0008
(0.0046)
0
(0.0047)
0.0001
(0.0047)
-0.0025
(0.005)
Observations
24,553
24,553
24,553
20,692
Cookies
Coefficient
(Std.)
0.0117***
(0.0025)
0.0103***
(0.0024)
0.01***
(0.0023)
0.016***
(0.0043)
Observations
317,932
317,932
317,932
66,087
Crackers
Coefficient
(Std.)
0.0081***
(0.0032)
0.0081***
(0.003)
0.0083***
(0.0029)
0.0131***
(0.0053)
Observations
115,658
115,658
115,658
24,771
Dish
Detergent
Coefficient
(Std.)
0.0257***
(0.0054)
0.0194***
(0.0045)
0.0194***
(0.0045)
0.0219***
(0.0057)
Observations
85,222
85,222
85,222
26,735
Fabric
Softener
Coefficient
(Std.)
0.0138**
(0.0086)
0.0032
(0.0077)
0.0035
(0.0077)
0.0176***
(0.0086)
Observations
85,337
85,337
85,337
27,488
Front-End-
Candies
Coefficient
(Std.)
-0.0027
(0.0047)
-0.0025
(0.0034)
-0.0024
(0.0034)
-0.0012
(0.003)
Observations
148,200
148,200
148,200
77,323
Frozen
Dinners
Coefficient
(Std.)
0.0434***
(0.0076)
0.0362***
(0.0069)
0.0354***
(0.0068)
0.0729***
(0.0108)
Observations
52,893
52,893
52,893
12,287
21
Table B2. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0209***
(0.0032)
0.0202***
(0.0029)
0.0202***
(0.0029)
0.0141***
(0.0037)
Observations
345,223
345,223
345,223
117,044
Frozen Juices
Coefficient
(Std.)
0.0177**
(0.0093)
0.0163**
(0.009)
0.0166**
(0.009)
0.0004
(0.0091)
Observations
118,582
118,582
118,582
40,517
Grooming
Products
Coefficient
(Std.)
0.0127***
(0.0039)
0.015***
(0.0038)
0.015***
(0.0038)
0.0203**
(0.0118)
Observations
101,944
101,944
101,944
22,102
Laundry
Detergents
Coefficient
(Std.)
0.0302***
(0.0055)
0.0192***
(0.0048)
0.0195***
(0.0048)
0.013***
(0.0058)
Observations
121,566
121,566
121,566
42,121
Oatmeal
Coefficient
(Std.)
0.0419***
(0.0152)
0.0366***
(0.0146)
0.037***
(0.0147)
0.0433***
(0.0171)
Observations
25,523
25,523
25,523
13,605
Paper Towels
Coefficient
(Std.)
0.014
(0.0168)
0.0084
(0.0176)
0.0084
(0.0175)
0.0279***
(0.0131)
Observations
48,199
48,199
48,199
9,243
Refrigerated
Juices
Coefficient
(Std.)
0.0236***
(0.0069)
0.013**
(0.007)
0.0131**
(0.0071)
0.0283***
(0.009)
Observations
108,965
108,965
108,965
23,705
Shampoos
Coefficient
(Std.)
0.0279***
(0.004)
0.0278***
(0.0038)
0.0278***
(0.0038)
0.0424***
(0.0114)
Observations
88,193
88,193
88,193
16,099
Snack
Crackers
Coefficient
(Std.)
-0.0041**
(0.0034)
-0.0033**
(0.0034)
-0.0031*
(0.0034)
0.0044
(0.0057)
Observations
176,527
176,527
176,527
38,123
Soaps
Coefficient
(Std.)
0.0169***
(0.0077)
0.007**
(0.007)
0.0094**
(0.0071)
0.0335***
(0.0113)
Observations
56,725
56,725
56,725
16,882
Soft Drinks
Coefficient
(Std.)
0.0079***
(0.0026)
0.0099***
(0.0025)
0.0096***
(0.0025)
-0.0003
(0.004)
Observations
243,837
243,837
243,837
49,989
Toothbrushes
Coefficient
(Std.)
0.0182***
(0.0061)
0.0119**
(0.0062)
0.0113**
(0.0061)
0.0385***
(0.013)
Observations
52,185
52,185
52,185
13,695
Toothpastes
Coefficient
(Std.)
0.0024
(0.0062)
0.0005
(0.0059)
0.0009
(0.0058)
0.0172**
(0.0088)
Observations
100,845
100,845
100,845
28,039
Average coefficients
0.0163
0.0121
0.0122
0.0188
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 15¢, and 0 otherwise. The main independent variable is the log of the average sales volume of product i in
store s over the sample period. Column 1 reports the results of the baseline regression that includes only the log of the
average sales volume and the fixed effects for months, years, stores, and products. In column 2, we add the following
controls: the log of the average price, the log of the absolute change in the wholesale price, and a control for sale- and
bounce-back prices, which we identify using a sales filter algorithm. In column 3, we add a dummy for 9-ending prices
as an additional control. In column 4, we focus on regular prices by excluding the sale- and bounce-back prices. We
estimate separate regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p
< 1%
22
Table B3. Category-level regressions of small price changes Δ and sales
volume
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0097***
(0.0034)
0.0058**
(0.003)
0.0054**
(0.003)
0.0132**
(0.0072)
Observations
74,451
74,451
74,451
24,729
Bath Soap
Coefficient
(Std.)
0.0093**
(0.0054)
0.0085**
(0.0049)
0.0084**
(0.0046)
0.0004
(0.0127)
Observations
6,650
6,650
6,650
1,466
Bathroom
Tissues
Coefficient
(Std.)
0.022***
(0.0054)
0.0095***
(0.0044)
0.0095***
(0.0043)
0.015**
(0.0082)
Observations
56,458
56,458
56,458
19,285
Beer
Coefficient
(Std.)
0.0017***
(0.0004)
0.0034***
(0.0006)
0.0034***
(0.0006)
0.0196***
(0.004)
Observations
187,691
187,691
187,691
12,080
Bottled Juice
Coefficient
(Std.)
0.0115***
(0.0039)
0.0068***
(0.0032)
0.0068***
(0.0031)
0.0237***
(0.0095)
Observations
224,857
224,857
224,857
60,015
Canned Soup
Coefficient
(Std.)
-0.0032*
(0.0031)
-0.0038**
(0.0028)
-0.0034**
(0.0028)
-0.0061*
(0.006)
Observations
233,779
233,779
233,779
95,310
Canned Tuna
Coefficient
(Std.)
0.0069***
(0.0026)
0.0038**
(0.0023)
0.0038**
(0.0023)
0.0072*
(0.0063)
Observations
112,629
112,629
112,629
31,922
Cereals
Coefficient
(Std.)
0.01***
(0.0039)
0.011***
(0.0033)
0.011***
(0.0033)
0.0237***
(0.0063)
Observations
141,087
141,087
141,087
72,789
Cheese
Coefficient
(Std.)
0.0051**
(0.0027)
0.0043***
(0.002)
0.0042***
(0.002)
0.0149***
(0.0048)
Observations
357,679
357,679
357,679
92,758
Cigarettes
Coefficient
(Std.)
0.0041**
(0.0026)
0.0049**
(0.0026)
0.0049**
(0.0026)
0.0073***
(0.0029)
Observations
24,553
24,553
24,553
20,692
Cookies
Coefficient
(Std.)
0.0032***
(0.0008)
0.0025***
(0.0007)
0.0025***
(0.0007)
0.0073***
(0.0022)
Observations
317,932
317,932
317,932
66,087
Crackers
Coefficient
(Std.)
0.0015**
(0.0008)
0.0011**
(0.0008)
0.0012**
(0.0008)
0.0028*
(0.0031)
Observations
115,658
115,658
115,658
24,771
Dish
Detergent
Coefficient
(Std.)
0.0139***
(0.0022)
0.009***
(0.0018)
0.0091***
(0.0018)
0.0233***
(0.0047)
Observations
85,222
85,222
85,222
26,735
Fabric
Softener
Coefficient
(Std.)
0.0104***
(0.004)
0.0035*
(0.0033)
0.0037*
(0.0033)
0.0082*
(0.0078)
Observations
85,337
85,337
85,337
27,488
Front-End-
Candies
Coefficient
(Std.)
-0.002**
(0.0012)
-0.002**
(0.0011)
-0.0021**
(0.0011)
0.0009
(0.0015)
Observations
148,200
148,200
148,200
77,323
Frozen
Dinners
Coefficient
(Std.)
0.0227***
(0.005)
0.0156***
(0.0038)
0.0162***
(0.0037)
0.0246***
(0.0091)
Observations
52,893
52,893
52,893
12,287
23
Table B3. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0097***
(0.0018)
0.0092***
(0.0016)
0.0093***
(0.0015)
0.0266***
(0.0027)
Observations
345,223
345,223
345,223
117,044
Frozen Juices
Coefficient
(Std.)
0.0152***
(0.0035)
0.0131***
(0.003)
0.0131***
(0.003)
0.0206***
(0.0068)
Observations
118,582
118,582
118,582
40,517
Grooming
Products
Coefficient
(Std.)
0.0026*
(0.0023)
0.0031**
(0.0023)
0.0033**
(0.0023)
0.0048
(0.0086)
Observations
101,944
101,944
101,944
22,102
Laundry
Detergents
Coefficient
(Std.)
0.019***
(0.0044)
0.0101***
(0.003)
0.0105***
(0.003)
0.0116**
(0.0059)
Observations
121,566
121,566
121,566
42,121
Oatmeal
Coefficient
(Std.)
0.0428***
(0.0153)
0.0314***
(0.0105)
0.0303***
(0.0102)
0.0511***
(0.0141)
Observations
25,523
25,523
25,523
13,605
Paper Towels
Coefficient
(Std.)
0.0053**
(0.0037)
0.0066**
(0.0035)
0.0068**
(0.0035)
0.0255**
(0.0147)
Observations
48,199
48,199
48,199
9,243
Refrigerated
Juices
Coefficient
(Std.)
0.0156***
(0.0038)
0.0082***
(0.0029)
0.0082***
(0.0029)
0.0212***
(0.0081)
Observations
108,965
108,965
108,965
23,705
Shampoos
Coefficient
(Std.)
0.0022***
(0.0011)
0.0025***
(0.0011)
0.0025***
(0.0011)
0.0127***
(0.0052)
Observations
88,193
88,193
88,193
16,099
Snack
Crackers
Coefficient
(Std.)
0.0005
(0.0009)
0.0008*
(0.0009)
0.0008*
(0.0009)
0.0035*
(0.0028)
Observations
176,527
176,527
176,527
38,123
Soaps
Coefficient
(Std.)
0.019***
(0.0059)
0.0088**
(0.0048)
0.0101**
(0.0048)
0.0273***
(0.0111)
Observations
56,725
56,725
56,725
16,882
Soft Drinks
Coefficient
(Std.)
0.0017***
(0.0008)
0.0015**
(0.0008)
0.0012**
(0.0008)
0.0003
(0.0027)
Observations
243,837
243,837
243,837
49,989
Toothbrushes
Coefficient
(Std.)
0.0056***
(0.0022)
0.0044***
(0.0021)
0.0044***
(0.0021)
0.0166***
(0.0066)
Observations
52,185
52,185
52,185
13,695
Toothpastes
Coefficient
(Std.)
0.0066***
(0.0021)
0.0054***
(0.0019)
0.0056***
(0.0019)
0.0157***
(0.0055)
Observations
100,845
100,845
100,845
28,039
Average coefficients
0.0094
0.0065
0.0066
0.0146
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 2%, and 0 otherwise. The main independent variable is the log of the average sales volume of product i in
store s over the sample period. Column 1 reports the results of the baseline regression that includes only the log of the
average sales volume and the fixed effects for months, years, stores, and products. In column 2, we add the following
controls: the log of the average price, the log of the absolute change in the wholesale price, and a control for sale- and
bounce-back prices, which we identify using a sales filter algorithm. In column 3, we add a dummy for 9-ending prices
as an additional control. In column 4, we focus on regular prices by excluding the sale- and bounce-back prices. We
estimate separate regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p
< 1%
24
Table B4. Category-level regressions of small price changes
( 5%)P
and sales volume
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0266***
(0.0065)
0.0214***
(0.0061)
0.0204***
(0.0061)
0.0135**
(0.0103)
Observations
74,451
74,451
74,451
24,729
Bath Soap
Coefficient
(Std.)
0.0207**
(0.0148)
0.0144*
(0.0135)
0.0144*
(0.0134)
0.0176
(0.0329)
Observations
6,650
6,650
6,650
1,466
Bathroom
Tissues
Coefficient
(Std.)
0.0236***
(0.009)
0.0005
(0.0081)
0.0003
(0.0082)
0.0048
(0.0091)
Observations
56,458
56,458
56,458
19,285
Beer
Coefficient
(Std.)
0.0066***
(0.0015)
0.0115***
(0.0016)
0.0115***
(0.0016)
0.0444***
(0.0069)
Observations
187,691
187,691
187,691
12,080
Bottled Juice
Coefficient
(Std.)
-0.0025
(0.0071)
-0.0068*
(0.0064)
-0.0067*
(0.0066)
0.0195***
(0.0075)
Observations
224,857
224,857
224,857
60,015
Canned Soup
Coefficient
(Std.)
-0.0201**
(0.0114)
-0.0226**
(0.0111)
-0.0202**
(0.011)
0.0133**
(0.0086)
Observations
233,779
233,779
233,779
95,310
Canned Tuna
Coefficient
(Std.)
-0.0021
(0.0058)
-0.0064*
(0.0057)
-0.0065*
(0.0057)
0.0129**
(0.0088)
Observations
112,629
112,629
112,629
31,922
Cereals
Coefficient
(Std.)
-0.0003
(0.0076)
-0.0001
(0.0073)
0
(0.0073)
0.014**
(0.0073)
Observations
141,087
141,087
141,087
72,789
Cheese
Coefficient
(Std.)
0.0047*
(0.0037)
0.0043*
(0.0034)
0.004*
(0.0034)
0.0126***
(0.0044)
Observations
357,679
357,679
357,679
92,758
Cigarettes
Coefficient
(Std.)
-0.0007
(0.004)
-0.0037*
(0.0039)
-0.0038*
(0.004)
-0.0062**
(0.0046)
Observations
24,553
24,553
24,553
20,692
Cookies
Coefficient
(Std.)
0.0109***
(0.002)
0.0097***
(0.0021)
0.0096***
(0.002)
0.0102***
(0.0036)
Observations
317,932
317,932
317,932
66,087
Crackers
Coefficient
(Std.)
0.0024
(0.003)
0.0015
(0.003)
0.0019
(0.003)
0.0147***
(0.0061)
Observations
115,658
115,658
115,658
24,771
Dish
Detergent
Coefficient
(Std.)
0.0308***
(0.0049)
0.0249***
(0.0042)
0.025***
(0.0041)
0.0256***
(0.0055)
Observations
85,222
85,222
85,222
26,735
Fabric
Softener
Coefficient
(Std.)
0.0207***
(0.0079)
0.0104**
(0.0069)
0.011**
(0.0069)
0.0232***
(0.0082)
Observations
85,337
85,337
85,337
27,488
Front-End-
Candies
Coefficient
(Std.)
-0.0033**
(0.0026)
-0.0033**
(0.0025)
-0.0033**
(0.0025)
0.0015
(0.0023)
Observations
148,200
148,200
148,200
77,323
Frozen
Dinners
Coefficient
(Std.)
0.0385***
(0.0071)
0.0296***
(0.0065)
0.0295***
(0.0065)
0.0684***
(0.0099)
Observations
52,893
52,893
52,893
12,287
25
Table B4. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0186***
(0.0029)
0.0196***
(0.0026)
0.0197***
(0.0026)
0.0249***
(0.0035)
Observations
345,223
345,223
345,223
117,044
Frozen Juices
Coefficient
(Std.)
0.0244***
(0.0057)
0.0224***
(0.005)
0.0233***
(0.0048)
0.0323***
(0.0071)
Observations
118,582
118,582
118,582
40,517
Grooming
Products
Coefficient
(Std.)
0.0091***
(0.0038)
0.0104***
(0.0039)
0.0106***
(0.004)
0.0154**
(0.0097)
Observations
101,944
101,944
101,944
22,102
Laundry
Detergents
Coefficient
(Std.)
0.0273***
(0.006)
0.0153***
(0.0052)
0.0159***
(0.0052)
0.0119**
(0.0063)
Observations
121,566
121,566
121,566
42,121
Oatmeal
Coefficient
(Std.)
0.0424***
(0.0138)
0.0367***
(0.0135)
0.0362***
(0.0133)
0.0536***
(0.0115)
Observations
25,523
25,523
25,523
13,605
Paper Towels
Coefficient
(Std.)
0.0232**
(0.0126)
0.0226**
(0.0117)
0.0232**
(0.0115)
0.01
(0.0167)
Observations
48,199
48,199
48,199
9,243
Refrigerated
Juices
Coefficient
(Std.)
0.0264***
(0.0065)
0.0187***
(0.0064)
0.0187***
(0.0064)
0.0223**
(0.0116)
Observations
108,965
108,965
108,965
23,705
Shampoos
Coefficient
(Std.)
0.0176***
(0.0029)
0.0185***
(0.0029)
0.0185***
(0.0029)
0.0318***
(0.0089)
Observations
88,193
88,193
88,193
16,099
Snack
Crackers
Coefficient
(Std.)
0.0028*
(0.0026)
0.0035**
(0.0026)
0.0035**
(0.0026)
0.0173***
(0.0047)
Observations
176,527
176,527
176,527
38,123
Soaps
Coefficient
(Std.)
0.0295***
(0.009)
0.0182***
(0.0085)
0.0212***
(0.0084)
0.0509***
(0.0102)
Observations
56,725
56,725
56,725
16,882
Soft Drinks
Coefficient
(Std.)
0.0029***
(0.0013)
0.0028***
(0.0012)
0.0023**
(0.0012)
0.0012**
(0.0033)
Observations
243,837
243,837
243,837
49,989
Toothbrushes
Coefficient
(Std.)
0.0141***
(0.0059)
0.0108**
(0.006)
0.0103**
(0.006)
0.0314***
(0.0119)
Observations
52,185
52,185
52,185
13,695
Toothpastes
Coefficient
(Std.)
0.0083**
(0.0043)
0.0082**
(0.004)
0.0084***
(0.004)
0.0225***
(0.0083)
Observations
100,845
100,845
100,845
28,039
Average coefficients
0.0139
0.0101
0.0103
0.0212
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 5%, and 0 otherwise. The main independent variable is the log of the average sales volume of product i in
store s over the sample period. Column 1 reports the results of the baseline regression that includes only the log of the
average sales volume and the fixed effects for months, years, stores, and products. In column 2, we add the following
controls: the log of the average price, the log of the absolute change in the wholesale price, and a control for sale- and
bounce-back prices, which we identify using a sales filter algorithm. In column 3, we add a dummy for 9-ending prices
as an additional control. In column 4, we focus on regular prices by excluding the sale- and bounce-back prices. We
estimate separate regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p
< 1%
26
Table B5. Category-level regressions of small price changes (
P
50% of the
average price change) and sales volume
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0374***
(0.0074)
0.032***
(0.007)
0.0314***
(0.007)
0.0563***
(0.0108)
Observations
74,451
74,451
74,451
24,729
Bath Soap
Coefficient
(Std.)
0.0503***
(0.0138)
0.0433***
(0.0137)
0.0432***
(0.0136)
0.1405***
(0.0357)
Observations
6,650
6,650
6,650
1,466
Bathroom
Tissues
Coefficient
(Std.)
0.0184***
(0.0058)
0.0175***
(0.0068)
0.0174***
(0.0068)
0.0405***
(0.0097)
Observations
56,458
56,458
56,458
19,285
Beer
Coefficient
(Std.)
0.0057***
(0.0015)
0.012***
(0.0014)
0.012***
(0.0014)
0.0648***
(0.0084)
Observations
187,691
187,691
187,691
12,080
Bottled Juice
Coefficient
(Std.)
0.0132***
(0.0053)
0.01**
(0.0054)
0.0101**
(0.0054)
0.0193***
(0.0087)
Observations
224,857
224,857
224,857
60,015
Canned Soup
Coefficient
(Std.)
-0.0043
(0.0066)
-0.0003
(0.0069)
0.0017
(0.0068)
0.0129**
(0.0073)
Observations
233,779
233,779
233,779
95,310
Canned Tuna
Coefficient
(Std.)
0.0125***
(0.0048)
0.0118***
(0.0048)
0.0116***
(0.0049)
0.0222***
(0.0074)
Observations
112,629
112,629
112,629
31,922
Cereals
Coefficient
(Std.)
-0.0018
(0.0046)
-0.0012
(0.0048)
-0.0011
(0.0048)
0.0082*
(0.0074)
Observations
141,087
141,087
141,087
72,789
Cheese
Coefficient
(Std.)
0.0078***
(0.0036)
0.0066**
(0.004)
0.0065**
(0.004)
0.0158***
(0.0059)
Observations
357,679
357,679
357,679
92,758
Cigarettes
Coefficient
(Std.)
0.107***
(0.0084)
0.1075***
(0.0081)
0.1075***
(0.0081)
0.1225***
(0.009)
Observations
24,553
24,553
24,553
20,692
Cookies
Coefficient
(Std.)
0.0153***
(0.0031)
0.0127***
(0.0031)
0.0126***
(0.0031)
0.0367***
(0.006)
Observations
317,932
317,932
317,932
66,087
Crackers
Coefficient
(Std.)
0.0152***
(0.0049)
0.0138***
(0.005)
0.0139***
(0.005)
0.0253***
(0.0078)
Observations
115,658
115,658
115,658
24,771
Dish
Detergent
Coefficient
(Std.)
0.0092***
(0.0042)
0.004*
(0.0041)
0.0042*
(0.0042)
0.0137**
(0.0072)
Observations
85,222
85,222
85,222
26,735
Fabric
Softener
Coefficient
(Std.)
0.0125**
(0.0065)
0.0088**
(0.0065)
0.0093**
(0.0066)
0.0317***
(0.0102)
Observations
85,337
85,337
85,337
27,488
Front-End-
Candies
Coefficient
(Std.)
0.0199***
(0.0052)
0.0239***
(0.0052)
0.0241***
(0.0052)
0.0128***
(0.0043)
Observations
148,200
148,200
148,200
77,323
Frozen
Dinners
Coefficient
(Std.)
0.0285***
(0.0079)
0.0312***
(0.0085)
0.0305***
(0.0084)
0.0678***
(0.0128)
Observations
52,893
52,893
52,893
12,287
27
Table B5. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0286***
(0.0032)
0.0377***
(0.0034)
0.0375***
(0.0034)
0.0308***
(0.0036)
Observations
345,223
345,223
345,223
117,044
Frozen Juices
Coefficient
(Std.)
0.0143***
(0.0066)
0.0125**
(0.0076)
0.013**
(0.0077)
0.0229***
(0.0103)
Observations
118,582
118,582
118,582
40,517
Grooming
Products
Coefficient
(Std.)
0.0417***
(0.0037)
0.0435***
(0.0038)
0.0434***
(0.0038)
0.0797***
(0.009)
Observations
101,944
101,944
101,944
22,102
Laundry
Detergents
Coefficient
(Std.)
0.0159***
(0.0044)
0.0113***
(0.004)
0.0117***
(0.004)
0.0198***
(0.0066)
Observations
121,566
121,566
121,566
42,121
Oatmeal
Coefficient
(Std.)
-0.0063
(0.0101)
-0.0135*
(0.012)
-0.0133*
(0.012)
0.0112
(0.0167)
Observations
25,523
25,523
25,523
13,605
Paper Towels
Coefficient
(Std.)
0.0111**
(0.0071)
0.0161***
(0.0071)
0.0167***
(0.0071)
-0.004
(0.0188)
Observations
48,199
48,199
48,199
9,243
Refrigerated
Juices
Coefficient
(Std.)
0.0068**
(0.0049)
0.0034
(0.0052)
0.0034
(0.0052)
0.0211**
(0.0113)
Observations
108,965
108,965
108,965
23,705
Shampoos
Coefficient
(Std.)
0.0522***
(0.0035)
0.0521***
(0.0035)
0.0521***
(0.0035)
0.1111***
(0.0112)
Observations
88,193
88,193
88,193
16,099
Snack
Crackers
Coefficient
(Std.)
0.0048*
(0.0048)
0.0007
(0.0052)
0.0008
(0.0052)
0.0215***
(0.0063)
Observations
176,527
176,527
176,527
38,123
Soaps
Coefficient
(Std.)
0.0137***
(0.0067)
0.0049
(0.0069)
0.0077*
(0.007)
0.0332***
(0.0118)
Observations
56,725
56,725
56,725
16,882
Soft Drinks
Coefficient
(Std.)
0.0137***
(0.0022)
0.0119***
(0.0024)
0.0122***
(0.0024)
0.0152***
(0.0043)
Observations
243,837
243,837
243,837
49,989
Toothbrushes
Coefficient
(Std.)
0.0445***
(0.0058)
0.0394***
(0.0055)
0.0387***
(0.0056)
0.0881***
(0.0125)
Observations
52,185
52,185
52,185
13,695
Toothpastes
Coefficient
(Std.)
0.0287***
(0.0046)
0.0287***
(0.0047)
0.0288***
(0.0047)
0.0613***
(0.0092)
Observations
100,845
100,845
100,845
28,039
Average coefficients
0.0213
0.0201
0.0203
0.0415
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to
where
is the average size of a price change of product in store , and 0 otherwise. The
main independent variable is the log of the average sales volume of product i in store s over the sample period. Column
1 reports the results of the baseline regression that includes only the log of the average sales volume and the fixed
effects for months, years, stores, and products. In column 2, we add the following controls: the log of the average price,
the log of the absolute change in the wholesale price, and a control for sale- and bounce-back prices, which we identify
using a sales filter algorithm. In column 3, we add a dummy for 9-ending prices as an additional control. In column 4,
we focus on regular prices by excluding the sale- and bounce-back prices. We estimate separate regressions for each
product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
28
Table B6. Category-level regressions of small price changes (
P
33% of the average
price change) and sales volume
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0293***
(0.0045)
0.0248***
(0.0043)
0.0242***
(0.0042)
0.0414***
(0.0088)
Observations
74,451
74,451
74,451
24,729
Bath Soap
Coefficient
(Std.)
0.0304***
(0.0113)
0.026***
(0.0107)
0.026***
(0.0105)
0.0736***
(0.0225)
Observations
6,650
6,650
6,650
1,466
Bathroom
Tissues
Coefficient
(Std.)
0.0057*
(0.005)
0.0107**
(0.0064)
0.0106**
(0.0064)
0.0297***
(0.0123)
Observations
56,458
56,458
56,458
19,285
Beer
Coefficient
(Std.)
0.0023***
(0.0006)
0.0065***
(0.0008)
0.0064***
(0.0008)
0.0526***
(0.0069)
Observations
187,691
187,691
187,691
12,080
Bottled Juice
Coefficient
(Std.)
0.0184***
(0.0041)
0.0157***
(0.0044)
0.0157***
(0.0044)
0.0183***
(0.0081)
Observations
224,857
224,857
224,857
60,015
Canned Soup
Coefficient
(Std.)
-0.0072*
(0.0057)
-0.0028
(0.006)
-0.0014
(0.0058)
0.0121**
(0.0073)
Observations
233,779
233,779
233,779
95,310
Canned Tuna
Coefficient
(Std.)
0.0102***
(0.0036)
0.0082***
(0.0032)
0.0081***
(0.0032)
0.0161***
(0.0063)
Observations
112,629
112,629
112,629
31,922
Cereals
Coefficient
(Std.)
0.0081***
(0.0039)
0.0088***
(0.004)
0.0088***
(0.004)
0.0163***
(0.0069)
Observations
141,087
141,087
141,087
72,789
Cheese
Coefficient
(Std.)
0.0078***
(0.0033)
0.0068**
(0.0035)
0.0068**
(0.0035)
0.0142***
(0.0061)
Observations
357,679
357,679
357,679
92,758
Cigarettes
Coefficient
(Std.)
0.0476***
(0.0061)
0.0492***
(0.0059)
0.0493***
(0.0058)
0.0588***
(0.0065)
Observations
24,553
24,553
24,553
20,692
Cookies
Coefficient
(Std.)
0.0121***
(0.0023)
0.0103***
(0.0025)
0.0102***
(0.0024)
0.0148***
(0.0043)
Observations
317,932
317,932
317,932
66,087
Crackers
Coefficient
(Std.)
0.0104***
(0.0041)
0.0092***
(0.0041)
0.0093***
(0.0041)
0.0195***
(0.006)
Observations
115,658
115,658
115,658
24,771
Dish
Detergent
Coefficient
(Std.)
0.0073***
(0.0028)
0.0034**
(0.0029)
0.0036*
(0.0029)
0.0181***
(0.0048)
Observations
85,222
85,222
85,222
26,735
Fabric
Softener
Coefficient
(Std.)
0.0098**
(0.0061)
0.0066**
(0.0059)
0.0069*
(0.006)
0.033***
(0.0097)
Observations
85,337
85,337
85,337
27,488
Front-End-
Candies
Coefficient
(Std.)
0.0107***
(0.0046)
0.0132***
(0.0045)
0.0134***
(0.0045)
0.0115***
(0.0039)
Observations
148,200
148,200
148,200
77,323
Frozen
Dinners
Coefficient
(Std.)
0.0312***
(0.0078)
0.0339***
(0.0087)
0.0339***
(0.0086)
0.0534***
(0.0144)
Observations
52,893
52,893
52,893
12,287
29
Table B6. (Cont.)
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or to
where
is the average size of a price change of product in store , and 0 otherwise. The main
independent variable is the log of the average sales volume of product i in store s over the sample period. Column 1
reports the results of the baseline regression that includes only the log of the average sales volume and the fixed effects
for months, years, stores, and products. In column 2, we add the following controls: the log of the average price, the log
of the absolute change in the wholesale price, and a control for sale- and bounce-back prices, which we identify using
a sales filter algorithm. In column 3, we add a dummy for 9-ending prices as an additional control. In column 4, we
focus on regular prices by excluding the sale- and bounce-back prices. We estimate separate regressions for each product
category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0332***
(0.003)
0.0405***
(0.0031)
0.0404***
(0.0031)
0.0311***
(0.0034)
Observations
345,223
345,223
345,223
117,044
Frozen Juices
Coefficient
(Std.)
0.0251***
(0.0067)
0.0228***
(0.0076)
0.0232***
(0.0077)
0.0289***
(0.009)
Observations
118,582
118,582
118,582
40,517
Grooming
Products
Coefficient
(Std.)
0.0279***
(0.0031)
0.029***
(0.003)
0.0291***
(0.003)
0.0645***
(0.008)
Observations
101,944
101,944
101,944
22,102
Laundry
Detergents
Coefficient
(Std.)
0.0092***
(0.0033)
0.005**
(0.0032)
0.0053**
(0.0032)
0.0104**
(0.0057)
Observations
121,566
121,566
121,566
42,121
Oatmeal
Coefficient
(Std.)
-0.0023
(0.0102)
-0.0087
(0.0121)
-0.0094
(0.012)
0.0159*
(0.0172)
Observations
25,523
25,523
25,523
13,605
Paper Towels
Coefficient
(Std.)
0.0122**
(0.009)
0.0174**
(0.0092)
0.0179**
(0.0092)
0.0161**
(0.0151)
Observations
48,199
48,199
48,199
9,243
Refrigerated
Juices
Coefficient
(Std.)
0.0095**
(0.005)
0.0061*
(0.0049)
0.0061*
(0.0048)
0.0122**
(0.0126)
Observations
108,965
108,965
108,965
23,705
Shampoos
Coefficient
(Std.)
0.0328***
(0.0027)
0.0325***
(0.0026)
0.0325***
(0.0026)
0.0829***
(0.0094)
Observations
88,193
88,193
88,193
16,099
Snack
Crackers
Coefficient
(Std.)
0.0037*
(0.0039)
0.0001
(0.0042)
0.0002
(0.0042)
0.0177***
(0.0047)
Observations
176,527
176,527
176,527
38,123
Soaps
Coefficient
(Std.)
0.0143***
(0.0055)
0.0083**
(0.0056)
0.01**
(0.0057)
0.0216**
(0.0121)
Observations
56,725
56,725
56,725
16,882
Soft Drinks
Coefficient
(Std.)
0.0143***
(0.0021)
0.0121***
(0.0024)
0.0119***
(0.0024)
0.0137***
(0.0031)
Observations
243,837
243,837
243,837
49,989
Toothbrushes
Coefficient
(Std.)
0.0277***
(0.0043)
0.0238***
(0.0041)
0.0234***
(0.0041)
0.0611***
(0.0108)
Observations
52,185
52,185
52,185
13,695
Toothpastes
Coefficient
(Std.)
0.0211***
(0.0034)
0.0204***
(0.0035)
0.0205***
(0.0035)
0.0425***
(0.0078)
Observations
100,845
100,845
100,845
28,039
Average coefficients
0.0160
0.0152
0.0153
0.0311
30
Table B7. Category-level regressions of small price changes (
P
25% of the average
price change) and sales volume
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0211***
(0.0035)
0.0177***
(0.0032)
0.0172***
(0.0032)
0.0337***
(0.0074)
Observations
74,451
74,451
74,451
24,729
Bath Soap
Coefficient
(Std.)
0.0209***
(0.0083)
0.0177***
(0.0077)
0.0176***
(0.0074)
0.0616***
(0.0241)
Observations
6,650
6,650
6,650
1,466
Bathroom
Tissues
Coefficient
(Std.)
0.0036
(0.005)
0.012***
(0.0057)
0.0119***
(0.0057)
0.028***
(0.0127)
Observations
56,458
56,458
56,458
19,285
Beer
Coefficient
(Std.)
0.0025***
(0.0006)
0.0054***
(0.0007)
0.0054***
(0.0007)
0.0377***
(0.0059)
Observations
187,691
187,691
187,691
12,080
Bottled Juice
Coefficient
(Std.)
0.016***
(0.004)
0.0134***
(0.0041)
0.0135***
(0.0041)
0.0221***
(0.0071)
Observations
224,857
224,857
224,857
60,015
Canned Soup
Coefficient
(Std.)
-0.0121**
(0.0062)
-0.0077*
(0.0065)
-0.0064*
(0.0064)
0.0152***
(0.0065)
Observations
233,779
233,779
233,779
95,310
Canned Tuna
Coefficient
(Std.)
0.0089***
(0.0037)
0.0066***
(0.0031)
0.0065***
(0.0031)
0.014***
(0.0063)
Observations
112,629
112,629
112,629
31,922
Cereals
Coefficient
(Std.)
0.0105***
(0.0035)
0.0111***
(0.0035)
0.0112***
(0.0034)
0.0195***
(0.0059)
Observations
141,087
141,087
141,087
72,789
Cheese
Coefficient
(Std.)
0.0085***
(0.0029)
0.0077***
(0.0029)
0.0077***
(0.0029)
0.0152***
(0.0053)
Observations
357,679
357,679
357,679
92,758
Cigarettes
Coefficient
(Std.)
0.0193***
(0.004)
0.0209***
(0.0039)
0.0209***
(0.0039)
0.025***
(0.0045)
Observations
24,553
24,553
24,553
20,692
Cookies
Coefficient
(Std.)
0.0086***
(0.0018)
0.0073***
(0.0019)
0.0072***
(0.0019)
0.0143***
(0.0035)
Observations
317,932
317,932
317,932
66,087
Crackers
Coefficient
(Std.)
0.0045**
(0.0025)
0.0038**
(0.0026)
0.0038**
(0.0025)
0.0068**
(0.0041)
Observations
115,658
115,658
115,658
24,771
Dish
Detergent
Coefficient
(Std.)
0.0093***
(0.0021)
0.006***
(0.0021)
0.0061***
(0.0021)
0.0183***
(0.0046)
Observations
85,222
85,222
85,222
26,735
Fabric
Softener
Coefficient
(Std.)
0.0128***
(0.0044)
0.0098***
(0.0043)
0.0101***
(0.0043)
0.0278***
(0.0087)
Observations
85,337
85,337
85,337
27,488
Front-End-
Candies
Coefficient
(Std.)
0.0125***
(0.0042)
0.0147***
(0.0042)
0.0148***
(0.0042)
0.0132***
(0.0041)
Observations
148,200
148,200
148,200
77,323
Frozen
Dinners
Coefficient
(Std.)
0.0373***
(0.0064)
0.0398***
(0.0076)
0.0401***
(0.0075)
0.0586***
(0.0123)
Observations
52,893
52,893
52,893
12,287
31
Table B7. (Cont.)
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or to
where
is the average size of a price change of product in store , and 0 otherwise. The main
independent variable is the log of the average sales volume of product i in store s over the sample period. Column 1
reports the results of the baseline regression that includes only the log of the average sales volume and the fixed effects
for months, years, stores, and products. In column 2, we add the following controls: the log of the average price, the
log of the absolute change in the wholesale price, and a control for sale- and bounce-back prices, which we identify
using a sales filter algorithm. In column 3, we add a dummy for 9-ending prices as an additional control. In column 4,
we focus on regular prices by excluding the sale- and bounce-back prices. We estimate separate regressions for each
product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0324***
(0.0032)
0.0389***
(0.0035)
0.0389***
(0.0034)
0.0321***
(0.0039)
Observations
345,223
345,223
345,223
117,044
Frozen Juices
Coefficient
(Std.)
0.0279***
(0.0062)
0.0255***
(0.0068)
0.0259***
(0.0068)
0.0312***
(0.0089)
Observations
118,582
118,582
118,582
40,517
Grooming
Products
Coefficient
(Std.)
0.0149***
(0.0021)
0.0156***
(0.0022)
0.0157***
(0.0022)
0.0368***
(0.0062)
Observations
101,944
101,944
101,944
22,102
Laundry
Detergents
Coefficient
(Std.)
0.0013
(0.0025)
-0.0018
(0.0024)
-0.0017
(0.0024)
0.0011
(0.0054)
Observations
121,566
121,566
121,566
42,121
Oatmeal
Coefficient
(Std.)
0.0065
(0.0082)
0.0011
(0.0095)
-0.0002
(0.0094)
0.0022
(0.0145)
Observations
25,523
25,523
25,523
13,605
Paper Towels
Coefficient
(Std.)
0.0074
(0.0102)
0.0116*
(0.0106)
0.0123*
(0.0105)
0.0265**
(0.0132)
Observations
48,199
48,199
48,199
9,243
Refrigerated
Juices
Coefficient
(Std.)
0.0094***
(0.0041)
0.006**
(0.0041)
0.0061**
(0.0041)
0.0151**
(0.0108)
Observations
108,965
108,965
108,965
23,705
Shampoos
Coefficient
(Std.)
0.018***
(0.0021)
0.018***
(0.002)
0.018***
(0.002)
0.054***
(0.0077)
Observations
88,193
88,193
88,193
16,099
Snack
Crackers
Coefficient
(Std.)
0.0044**
(0.0027)
0.0015
(0.0027)
0.0015
(0.0027)
0.0126***
(0.0046)
Observations
176,527
176,527
176,527
38,123
Soaps
Coefficient
(Std.)
0.0184***
(0.005)
0.0138***
(0.005)
0.015***
(0.0051)
0.0251***
(0.0109)
Observations
56,725
56,725
56,725
16,882
Soft Drinks
Coefficient
(Std.)
0.016***
(0.0026)
0.0136***
(0.0027)
0.0131***
(0.0028)
0.0132***
(0.0032)
Observations
243,837
243,837
243,837
49,989
Toothbrushes
Coefficient
(Std.)
0.0156***
(0.0043)
0.013***
(0.004)
0.0127***
(0.004)
0.0427***
(0.0095)
Observations
52,185
52,185
52,185
13,695
Toothpastes
Coefficient
(Std.)
0.0178***
(0.0027)
0.0168***
(0.0026)
0.0169***
(0.0026)
0.0315***
(0.007)
Observations
100,845
100,845
100,845
28,039
Average coefficients
0.0129
0.0124
0.0125
0.0253
32
Table B8. Category-level regressions of small price changes (
P
10% of the average
price change) and sales volume
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0067***
(0.0018)
0.0057***
(0.0017)
0.0055***
(0.0017)
0.0122***
(0.0047)
Observations
74,451
74,451
74,451
24,729
Bath Soap
Coefficient
(Std.)
0.005***
(0.0021)
0.0045***
(0.0019)
0.0044***
(0.0019)
-0.0015
(0.0107)
Observations
6,650
6,650
6,650
1,466
Bathroom
Tissues
Coefficient
(Std.)
-0.0058**
(0.0029)
0.0069**
(0.0039)
0.0069**
(0.0039)
0.0207***
(0.0078)
Observations
56,458
56,458
56,458
19,285
Beer
Coefficient
(Std.)
0.0015***
(0.0004)
0.0031***
(0.0006)
0.0031***
(0.0006)
0.0191***
(0.004)
Observations
187,691
187,691
187,691
12,080
Bottled Juice
Coefficient
(Std.)
0.0029**
(0.0015)
0.0019*
(0.0015)
0.0019*
(0.0015)
0.0039*
(0.0045)
Observations
224,857
224,857
224,857
60,015
Canned Soup
Coefficient
(Std.)
0.0001
(0.002)
0.0031**
(0.0023)
0.0033**
(0.0023)
0.0128***
(0.004)
Observations
233,779
233,779
233,779
95,310
Canned Tuna
Coefficient
(Std.)
0.0032***
(0.0013)
0.0021***
(0.0011)
0.0021**
(0.0011)
0.0089***
(0.0029)
Observations
112,629
112,629
112,629
31,922
Cereals
Coefficient
(Std.)
0.0038***
(0.0015)
0.004***
(0.0015)
0.004***
(0.0015)
0.0094***
(0.003)
Observations
141,087
141,087
141,087
72,789
Cheese
Coefficient
(Std.)
0.0018***
(0.0008)
0.0015***
(0.0008)
0.0015**
(0.0008)
0.0075***
(0.0026)
Observations
357,679
357,679
357,679
92,758
Cigarettes
Coefficient
(Std.)
-0.001
(0.0013)
-0.0004
(0.0013)
-0.0004
(0.0013)
-0.0004
(0.0015)
Observations
24,553
24,553
24,553
20,692
Cookies
Coefficient
(Std.)
0.0013***
(0.0005)
0.0012***
(0.0005)
0.0012***
(0.0004)
0.0028***
(0.0011)
Observations
317,932
317,932
317,932
66,087
Crackers
Coefficient
(Std.)
-0.0002
(0.0005)
-0.0003
(0.0005)
-0.0002
(0.0005)
0.0014*
(0.0015)
Observations
115,658
115,658
115,658
24,771
Dish
Detergent
Coefficient
(Std.)
0.0047***
(0.0013)
0.0036***
(0.0012)
0.0037***
(0.0012)
0.0087***
(0.0033)
Observations
85,222
85,222
85,222
26,735
Fabric
Softener
Coefficient
(Std.)
0.0014
(0.0018)
0.0009
(0.0018)
0.001
(0.0018)
0.0034
(0.0055)
Observations
85,337
85,337
85,337
27,488
Front-End-
Candies
Coefficient
(Std.)
0.0077***
(0.0025)
0.0093***
(0.0028)
0.0093***
(0.0028)
0.0079***
(0.0032)
Observations
148,200
148,200
148,200
77,323
Frozen
Dinners
Coefficient
(Std.)
0.028***
(0.0056)
0.0279***
(0.0061)
0.0288***
(0.006)
0.0425***
(0.0124)
Observations
52,893
52,893
52,893
12,287
33
Table B8. (Cont.)
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or to
where
is the average size of a price change of product in store , and 0 otherwise. The main
independent variable is the log of the average sales volume of product i in store s over the sample period. Column 1
reports the results of the baseline regression that includes only the log of the average sales volume and the fixed effects
for months, years, stores, and products. In column 2, we add the following controls: the log of the average price, the log
of the absolute change in the wholesale price, and a control for sale- and bounce-back prices, which we identify using
a sales filter algorithm. In column 3, we add a dummy for 9-ending prices as an additional control. In column 4, we
focus on regular prices by excluding the sale- and bounce-back prices. We estimate separate regressions for each product
category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0157***
(0.0023)
0.02***
(0.0024)
0.0201***
(0.0024)
0.0322***
(0.0036)
Observations
345,223
345,223
345,223
117,044
Frozen Juices
Coefficient
(Std.)
0.0165***
(0.0041)
0.0149***
(0.0043)
0.0151***
(0.0042)
0.0251***
(0.006)
Observations
118,582
118,582
118,582
40,517
Grooming
Products
Coefficient
(Std.)
0.0013***
(0.0006)
0.0014***
(0.0006)
0.0015***
(0.0006)
0.0031**
(0.0022)
Observations
101,944
101,944
101,944
22,102
Laundry
Detergents
Coefficient
(Std.)
-0.0009
(0.0015)
-0.0016*
(0.0014)
-0.0016*
(0.0014)
-0.0034*
(0.0036)
Observations
121,566
121,566
121,566
42,121
Oatmeal
Coefficient
(Std.)
0.0032
(0.0042)
0.0014
(0.0042)
0.001
(0.0041)
0.0056
(0.0081)
Observations
25,523
25,523
25,523
13,605
Paper Towels
Coefficient
(Std.)
0.0058**
(0.0034)
0.0062**
(0.0034)
0.0065**
(0.0034)
0.0143***
(0.0067)
Observations
48,199
48,199
48,199
9,243
Refrigerated
Juices
Coefficient
(Std.)
0.0052***
(0.0014)
0.0033***
(0.0013)
0.0033***
(0.0013)
0.0165***
(0.0054)
Observations
108,965
108,965
108,965
23,705
Shampoos
Coefficient
(Std.)
0.0009***
(0.0003)
0.0009***
(0.0003)
0.0009***
(0.0003)
0.0041***
(0.0016)
Observations
88,193
88,193
88,193
16,099
Snack
Crackers
Coefficient
(Std.)
-0.0003
(0.0009)
-0.0007
(0.0009)
-0.0007
(0.0009)
0.0024*
(0.0019)
Observations
176,527
176,527
176,527
38,123
Soaps
Coefficient
(Std.)
0.0067***
(0.0022)
0.0057***
(0.0021)
0.0059***
(0.0021)
0.0107***
(0.0054)
Observations
56,725
56,725
56,725
16,882
Soft Drinks
Coefficient
(Std.)
0.0022***
(0.0007)
0.0014***
(0.0007)
0.0008*
(0.0007)
-0.002*
(0.0021)
Observations
243,837
243,837
243,837
49,989
Toothbrushes
Coefficient
(Std.)
0.0053***
(0.0013)
0.0047***
(0.0013)
0.0046***
(0.0013)
0.0119***
(0.004)
Observations
52,185
52,185
52,185
13,695
Toothpastes
Coefficient
(Std.)
0.0048***
(0.001)
0.0046***
(0.001)
0.0047***
(0.001)
0.0123***
(0.0032)
Observations
100,845
100,845
100,845
28,039
Average coefficients
0.0044
0.0047
0.0048
0.0101
34
Appendix C. Using all price changes
In the paper, we use observations on price changes only if we observe the price in
both week t and t+1 and the post change price remained unchanged for at least 2 weeks.
In this appendix, we re-run the regressions we report in Table 3 in the paper, but this
time: (1) using observations if we observe the price in both week t and t +1 and (2) using
observations on all price changes. As in the paper, we define small price changes as price
changes smaller than, or equal to, 10¢.
Table C1 presents the results of regressions equivalent to the regressions in Table 3
in the paper. The regressions take the following form:
, , , , ,
,,
ln( )
i s t i s i s t
t t s i i s t
small price change average sales volume
month year u
X
(C1)
where small price change is a dummy that equals 1 if a price change of product i in store
s at time t is less or equal to 10¢, and 0 otherwise. The average sales volume is the
average sales volume of product i in store s over the sample period. X is a matrix of other
control variables. Month and year are fixed effects for the month and the year of the price
change.
and
are fixed effects for stores and products, respectively, and u is an i.i.d
error term. We estimate separate regressions for each product category, clustering the
errors by product. We use all observations on price changes if we observe the price in
both week t and week t +1.
The values in the table are the coefficients of the log of the average sales volume. In
column 1, the only control variables are the log of the average sales volume, and the
dummies for months, years, stores, and products. We find that all the coefficients of the
log of the average sales volume are positive and statistically significant. The average
coefficient is 0.030, suggesting that a 1% increase in the sales volume is associated with a
3.0% increase in the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). All the coefficients are
positive and statistically significant. The average coefficient is 0.025, suggesting that a
1% increase in the sales volume is associated with a 2.5% increase in the likelihood of a
35
small price change.
In column 3, we also add a control for 9-ending prices. All the coefficients are still
positive and statistically significant. The average coefficient is 0.023, suggesting that a
1% increase in the sales volume is associated with a 2.3% increase in the likelihood of a
small price change.
As a further control for the effects of sales on the results, in column 4 we focus on
regular prices by excluding all sale- and bounce-back prices. When we focus on regular
prices, the results are even stronger. All the coefficients are positive and statistically
significant. The average coefficient is 0.045, suggesting that a 1% increase in the sales
volume is associated with a 4.5% increase in the likelihood of a small price change.
Table C2 presents the results when we use observations on all price changes. In
column 1, the control variables are the log of the average sales volume, and the dummies
for months, years, stores, and products. We find that all the coefficients of the log of the
average sales volume are positive and 28 of the 29 are statistically significant at the 1%
level. The remaining coefficient is statistically significant at the 10% level. The average
coefficient is 0.035, suggesting that a 1% increase in the sales volume is associated with a
3.5% increase in the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). All the coefficients are
positive and statistically significant at the 1% level. The average coefficient is 0.035,
suggesting that a 1% increase in the sales volume is associated with a 3.5% increase in
the likelihood of a small price change.
In column 3, we add a control for 9-ending prices. All the coefficients are still
positive and statistically significant. The average coefficient is 0.032, suggesting that a
1% increase in the sales volume is associated with a 3.2% increase in the likelihood of a
small price change.
As a further control for the effects of sales on the estimation results, in column 4 we
focus on regular prices by excluding all sale- and bounce-back prices. When we focus on
regular prices, the results are even stronger. All the coefficients are positive and
statistically significant. The average coefficient is 0.055, suggesting that a 1% increase in
36
the sales volume is associated with a 5.5% increase in the likelihood of a small price
change.
37
Table C1. Category-level regressions of small price changes and sales volume
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0388***
(0.0033)
0.0305***
(0.0027)
0.0248***
(0.0025)
0.0475***
(0.0057)
Observations
278,052
278,052
278,052
75,945
Bath Soap
Coefficient
(Std.)
0.0409***
(0.0093)
0.0452***
(0.0095)
0.0422***
(0.0091)
0.0871***
(0.016)
Observations
35,795
35,795
35,795
6,555
Bathroom
Tissues
Coefficient
(Std.)
0.0372***
(0.0056)
0.0203***
(0.0053)
0.0177***
(0.0049)
0.0351***
(0.0069)
Observations
326,383
326,383
326,383
81,914
Beer
Coefficient
(Std.)
0.023***
(0.0015)
0.0249***
(0.0012)
0.0208***
(0.0012)
0.0691***
(0.005)
Observations
459,669
459,669
459,669
56,427
Bottled Juice
Coefficient
(Std.)
0.0554***
(0.0043)
0.0393***
(0.003)
0.0343***
(0.0031)
0.0368***
(0.0045)
Observations
960,033
960,033
960,033
244,199
Canned Soup
Coefficient
(Std.)
0.0272***
(0.004)
0.0151***
(0.0034)
0.0158***
(0.0033)
0.0217***
(0.0038)
Observations
947,633
947,633
947,633
278,451
Canned Tuna
Coefficient
(Std.)
0.037***
(0.0052)
0.0266***
(0.0044)
0.0225***
(0.0041)
0.0334***
(0.0047)
Observations
375,343
375,343
375,343
116,170
Cereals
Coefficient
(Std.)
0.0215***
(0.0026)
0.0168***
(0.0023)
0.0156***
(0.0024)
0.0263***
(0.0035)
Observations
724,902
724,902
724,902
260,110
Cheese
Coefficient
(Std.)
0.0374***
(0.0029)
0.0208***
(0.0022)
0.0169***
(0.0022)
0.0116***
(0.0031)
Observations
1,812,016
1,812,016
1,812,016
519,361
Cigarettes
Coefficient
(Std.)
0.019***
(0.0082)
0.0203***
(0.0068)
0.0197**
(0.0067)
0.0215***
(0.0045)
Observations
15,862
15,862
15,862
9,593
Cookies
Coefficient
(Std.)
0.0429***
(0.0017)
0.0372***
(0.0017)
0.0315***
(0.0015)
0.0543***
(0.0031)
Observations
1,357,300
1,357,300
1,357,300
229,189
Crackers
Coefficient
(Std.)
0.0544***
(0.0033)
0.0431***
(0.0031)
0.0389***
(0.0029)
0.0563***
(0.0061)
Observations
475,497
475,497
475,497
89,212
Dish
Detergent
Coefficient
(Std.)
0.0481***
(0.0038)
0.0357***
(0.003)
0.0315***
(0.0029)
0.0417***
(0.0043)
Observations
401,332
401,332
401,332
95,495
Fabric
Softener
Coefficient
(Std.)
0.0342***
(0.0038)
0.0245***
(0.0034)
0.0209***
(0.0035)
0.0428***
(0.0049)
Observations
378,836
378,836
378,836
101,979
Front-End-
Candies
Coefficient
(Std.)
0.0165***
(0.0039)
0.0091**
(0.0028)
0.0082**
(0.0028)
0.0113***
(0.0032)
Observations
490,627
490,627
490,627
155,230
Frozen
Dinners
Coefficient
(Std.)
0.0536***
(0.0027)
0.0408***
(0.0025)
0.0394***
(0.0025)
0.0907***
(0.006)
Observations
502,792
502,792
502,792
72,693
38
Table C1. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0354***
(0.0019)
0.0301***
(0.0017)
0.0292***
(0.0017)
0.0602***
(0.0032)
Observations
1,848,187
1,848,187
1,848,187
353,136
Frozen Juices
Coefficient
(Std.)
0.0342***
(0.0037)
0.0253***
(0.0031)
0.0227***
(0.003)
0.0299***
(0.0048)
Observations
659,305
659,305
659,305
150,138
Grooming
Products
Coefficient
(Std.)
0.0426***
(0.0024)
0.0455***
(0.0022)
0.039***
(0.0021)
0.0673***
(0.0061)
Observations
668,821
668,821
668,821
99,253
Laundry
Detergents
Coefficient
(Std.)
0.0185***
(0.0031)
0.0155***
(0.0027)
0.0126***
(0.0025)
0.0264***
(0.0047)
Observations
594,258
594,258
594,258
145,176
Oatmeal
Coefficient
(Std.)
0.0288***
(0.0071)
0.0172***
(0.0052)
0.0151**
(0.0052)
0.0319***
(0.0094)
Observations
168,988
168,988
168,988
63,575
Paper Towels
Coefficient
(Std.)
0.0378***
(0.0114)
0.0298***
(0.0116)
0.0285**
(0.0117)
0.0376***
(0.0096)
Observations
244,068
244,068
244,068
52,327
Refrigerated
Juices
Coefficient
(Std.)
0.031***
(0.0032)
0.0209***
(0.0027)
0.0182***
(0.0026)
0.0305***
(0.0041)
Observations
800,280
800,280
800,280
161,098
Shampoos
Coefficient
(Std.)
0.0323***
(0.0014)
0.0368***
(0.0014)
0.032***
(0.0013)
0.0674***
(0.0043)
Observations
713,730
713,730
713,730
86,458
Snack
Crackers
Coefficient
(Std.)
0.0434***
(0.0032)
0.0381***
(0.003)
0.0337***
(0.0027)
0.0661***
(0.004)
Observations
802,462
802,462
802,462
143,164
Soaps
Coefficient
(Std.)
0.0305***
(0.0014)
0.0265***
(0.001)
0.0222***
(0.0009)
0.0585***
(0.0027)
Observations
4,378,334
4,378,334
4,378,334
346,632
Soft Drinks
Coefficient
(Std.)
0.0545***
(0.006)
0.0413***
(0.0044)
0.0336***
(0.0042)
0.0555***
(0.0057)
Observations
333,170
333,170
333,170
94,295
Toothbrushes
Coefficient
(Std.)
0.0291***
(0.0032)
0.0317***
(0.0034)
0.0265***
(0.0032)
0.0619***
(0.006)
Observations
295,403
295,403
295,403
44,776
Toothpastes
Coefficient
(Std.)
0.0289***
(0.0032)
0.028***
(0.0027)
0.0241***
(0.0026)
0.0561***
(0.0063)
Observations
596,903
596,903
596,903
91,760
Average coefficients
0.030
0.025
0.023
0.045
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 10¢, and 0 otherwise. The main independent variable is the log of the average sales volume of product i in
store s over the sample period. Column 1 reports the results of baseline regression that includes only the average sales
volume and the fixed effects for months, years, stores, and products. In column 2, we add the following controls: the
log of the average price, the log of the absolute change in the wholesale price, and a control for sale- and bounce back
prices, which we identify using a sales filter algorithm. In column 3, we add a dummy for 9-ending prices as an
additional control. In column 4, we focus on regular prices by excluding the sale- and bounce-back prices. We estimate
separate regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
39
Table C2. Category-level regressions of small price changes
(10¢)P
and sales
volume, using all observations
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0288***
(0.0028)
0.0406***
(0.0028)
0.0362***
(0.0025)
0.0571***
(0.0045)
Observations
467,137
467,137
467,137
158,600
Bath Soap
Coefficient
(Std.)
0.0197***
(0.0071)
0.0479***
(0.0063)
0.0458***
(0.0061)
0.0701***
(0.0094)
Observations
76,548
76,548
76,548
22,545
Bathroom
Tissues
Coefficient
(Std.)
0.0377***
(0.0055)
0.0246***
(0.0054)
0.0218***
(0.005)
0.0392***
(0.0074)
Observations
347,559
347,559
347,559
88,388
Beer
Coefficient
(Std.)
0.0184***
(0.0014)
0.0287***
(0.0014)
0.0244***
(0.0013)
0.0561***
(0.0038)
Observations
617,181
617,181
617,181
95,440
Bottled Juice
Coefficient
(Std.)
0.0591***
(0.0041)
0.0467***
(0.0031)
0.041***
(0.0032)
0.0553***
(0.0048)
Observations
1,044,176
1,044,176
1,044,176
269,990
Canned Soup
Coefficient
(Std.)
0.029***
(0.0038)
0.0194***
(0.0033)
0.0196***
(0.0031)
0.0339***
(0.004)
Observations
1,041,402
1,041,402
1,041,402
309,450
Canned Tuna
Coefficient
(Std.)
0.0418***
(0.0049)
0.0342***
(0.0044)
0.0294***
(0.004)
0.0461***
(0.0053)
Observations
447,946
447,946
447,946
142,596
Cereals
Coefficient
(Std.)
0.0249***
(0.0026)
0.0242***
(0.0024)
0.0228***
(0.0025)
0.0407***
(0.0035)
Observations
771,993
771,993
771,993
281,908
Cheese
Coefficient
(Std.)
0.0407***
(0.0027)
0.0278***
(0.0023)
0.0232***
(0.0023)
0.0282***
(0.0037)
Observations
1,955,416
1,955,416
1,955,416
557,994
Cigarettes
Coefficient
(Std.)
0.024*
(0.0133)
0.0297***
(0.01)
0.0295***
(0.01)
0.0245**
(0.0096)
Observations
71,155
71,155
71,155
35,156
Cookies
Coefficient
(Std.)
0.0466***
(0.0017)
0.0464***
(0.0017)
0.0404***
(0.0015)
0.0681***
(0.0029)
Observations
1,581,102
1,581,102
1,581,102
297,881
Crackers
Coefficient
(Std.)
0.0601***
(0.0035)
0.0543***
(0.0033)
0.0494***
(0.0031)
0.0709***
(0.0057)
Observations
567,809
567,809
567,809
114,425
Dish
Detergent
Coefficient
(Std.)
0.0459***
(0.0041)
0.0411***
(0.0035)
0.0372***
(0.0034)
0.0618***
(0.0047)
Observations
497,210
497,210
497,210
115,037
Fabric
Softener
Coefficient
(Std.)
0.0333***
(0.0041)
0.0292***
(0.0036)
0.0247***
(0.0037)
0.0529***
(0.0049)
Observations
478,611
478,611
478,611
123,818
Front-End-
Candies
Coefficient
(Std.)
0.0184***
(0.0036)
0.0131***
(0.003)
0.0122***
(0.003)
0.0157***
(0.0034)
Observations
537,812
537,812
537,812
173,538
Frozen
Dinners
Coefficient
(Std.)
0.0584***
(0.0041)
0.0528***
(0.0034)
0.051***
(0.0035)
0.1183***
(0.0065)
Observations
567,884
567,884
567,884
86,750
40
Table C2. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0359***
(0.0019)
0.0392***
(0.0017)
0.0382***
(0.0017)
0.087***
(0.0038)
Observations
2,084,913
2,084,913
2,084,913
419,173
Frozen Juices
Coefficient
(Std.)
0.0389***
(0.0038)
0.0331***
(0.0035)
0.0297***
(0.0033)
0.0504***
(0.0054)
Observations
703,893
703,893
703,893
162,718
Grooming
Products
Coefficient
(Std.)
0.0307***
(0.0021)
0.0473***
(0.002)
0.0423***
(0.0019)
0.0601***
(0.0042)
Observations
1,092,785
1,092,785
1,092,785
210,384
Laundry
Detergents
Coefficient
(Std.)
0.0176***
(0.0032)
0.0191***
(0.0028)
0.0162***
(0.0024)
0.0367***
(0.0046)
Observations
766,390
766,390
766,390
183,661
Oatmeal
Coefficient
(Std.)
0.0333***
(0.0069)
0.023***
(0.0057)
0.0205***
(0.0056)
0.045***
(0.0115)
Observations
181,193
181,193
181,193
69,150
Paper Towels
Coefficient
(Std.)
0.0394***
(0.0111)
0.0327***
(0.0114)
0.0304***
(0.0114)
0.0482***
(0.0089)
Observations
274,918
274,918
274,918
58,771
Refrigerated
Juices
Coefficient
(Std.)
0.0348***
(0.0032)
0.0283***
(0.0029)
0.025***
(0.0027)
0.047***
(0.0048)
Observations
827,359
827,359
827,359
169,826
Shampoos
Coefficient
(Std.)
0.0185***
(0.0013)
0.0361***
(0.0012)
0.0328***
(0.0012)
0.0503***
(0.0026)
Observations
1,315,278
1,315,278
1,315,278
272,979
Snack
Crackers
Coefficient
(Std.)
0.0492***
(0.0035)
0.0483***
(0.0033)
0.0432***
(0.003)
0.084***
(0.0045)
Observations
903,254
903,254
903,254
172,655
Soaps
Coefficient
(Std.)
0.0321***
(0.0013)
0.0313***
(0.0011)
0.0266***
(0.0009)
0.0634***
(0.0027)
Observations
4,985,172
4,985,172
4,985,172
451,007
Soft Drinks
Coefficient
(Std.)
0.0519***
(0.0079)
0.0488***
(0.0044)
0.0398***
(0.0042)
0.0704***
(0.0059)
Observations
395,114
395,114
395,114
110,144
Toothbrushes
Coefficient
(Std.)
0.0197***
(0.0035)
0.0358***
(0.0034)
0.0305***
(0.0032)
0.0504***
(0.0056)
Observations
481,842
481,842
481,842
93,164
Toothpastes
Coefficient
(Std.)
0.0251***
(0.0029)
0.0349***
(0.0025)
0.0311***
(0.0025)
0.0684***
(0.0058)
Observations
771,084
771,084
771,084
136,134
Average coefficients
0.0350
0.0351
0.0316
0.0552
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 10¢, and 0 otherwise. The main independent variable is the log of the average sales volume of product i in
store s over the sample period. Column 1 reports the results of the baseline regression that includes only the log of the
average sales volume and the fixed effects for months, years, stores, and products. In column 2, we add the following
controls: the log of the average price, the log of the absolute change in the wholesale price, and a control for sale- and
bounce-back prices, which we identify using a sales filter algorithm. In column 3, we add a dummy for 9-ending prices
as an additional control. In column 4, we focus on regular prices by excluding the sale- and bounce-back prices. We
estimate separate regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p
< 1%
41
Appendix D. Using a rolling 52-week window to calculate the average sales volume
In the paper, we calculate the average sales volume for each product in each store
over the entire period. This has the advantage of using a long-term “expected” sales
volume for each product in each store. However, it implicitly assumes that the retailer can
forecast future sales.
An alternative is to assume that the retailer makes decisions based on a recent past.
To control for this possibility, we calculate the average sales volume for each product in
each store based on data from the previous 52 weeks.
We then use the results to re-estimate regressions similar to the ones that we report
in Table 3 in the paper. The regressions take the following form:
, , , , ,
,,
ln( )
i s t i s i s t
t t s i i s t
small price change average sales volume
month year u
X
(D1)
where small price change is a dummy that equals 1 if a price change of product i in store
s at time t is less or equal to 10¢, and 0 otherwise. The average sales volume is the
average sales volume of product i in store s over the 52 weeks preceding week t. X is a
matrix of other control variables. Month and year are fixed effects for the month and the
year of the price change.
and
are fixed effects for stores and products,
respectively, and u is an i.i.d error term. We estimate separate regressions for each
product category, clustering the errors by product.
The results are summarized in Table D1. The values in the table are the coefficients
of the log of the average sales volume. In column 1, the only control variables are the log
of the average sales volume, and the dummies for months, years, stores, and products.
We find that 24 of the 29 coefficients of the log of the average sales volume are positive
and that 16 of them are statistically significant. One more coefficient is marginally
significant. None of the five negative coefficients are statistically significant. The average
coefficient is 0.018, suggesting that a 1% increase in the sales volume is associated with a
1.8% increase in the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). We find that 25 of the 29
42
coefficients are positive and that 17 of them are statistically significant. None of the four
negative coefficients are statistically significant. The average coefficient is 0.017,
suggesting that a 1% increase in the sales volume is associated with a 1.7% increase in
the likelihood of a small price change.
In column 3, we also add a control for 9-ending prices. Again, we find that 25 of the
29 coefficients are positive and that 16 of them are statistically significant. One more
coefficient is marginally statistically significant. None of the negative coefficients is
statistically significant. The average coefficient is 0.015, suggesting that a 1% increase in
the sales volume is associated with a 1.5% increase in the likelihood of a small price
change.
As a further control for the effects of sales on the results, in column 4 we focus on
regular prices by excluding all sale- and bounce-back prices. When we focus on regular
prices, the results are stronger. We find that 27 of the 29 coefficients are positive and 21
of them are statistically significant. One more coefficient is marginally significant. Out of
the two negative coefficients, one (cereals) is marginally significant. The average
coefficient is 0.31, suggesting that a 1% increase in the sales volume is associated with a
3.1% increase in the likelihood of a small price change.
Thus, basing the estimation on the sales volume of the more recent period does not
change our main results. The correlation between small price changes and sales volume
holds in a large majority of the product categories.
43
Table D1. Category-level regressions of small price changes
(10¢)P
, using a rolling
52-week window for sales volume
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0339***
(0.0084)
0.0262***
(0.0074)
0.0215***
(0.0071)
0.0358**
(0.0139)
Observations
258,282
258,282
258,282
71,945
Bath Soap
Coefficient
(Std.)
0.0263***
(0.0076)
0.0246***
(0.0075)
0.0256***
(0.0072)
0.0421***
(0.015)
Observations
31,704
31,704
31,704
5,186
Bathroom
Tissues
Coefficient
(Std.)
0.0155
(0.0134)
0.0084
(0.0111)
0.0051
(0.0101)
0.0225**
(0.0104)
Observations
311,206
311,206
311,206
76,063
Beer
Coefficient
(Std.)
0.0172***
(0.0019)
0.0146***
(0.0016)
0.0111***
(0.0016)
0.0318***
(0.0062)
Observations
410,854
410,854
410,854
50,131
Bottled Juice
Coefficient
(Std.)
0.0225***
(0.007)
0.0122**
(0.0057)
0.0102*
(0.0059)
0.001
(0.0075)
Observations
917,557
917,557
917,557
228,910
Canned Soup
Coefficient
(Std.)
-0.0107
(0.0078)
-0.0038
(0.007)
-0.0015
(0.007)
0.0116
(0.0076)
Observations
890,145
890,145
890,145
256,793
Canned Tuna
Coefficient
(Std.)
0.001
(0.0112)
0.004
(0.0091)
0.0014
(0.0088)
0.0257***
(0.0075)
Observations
354,012
354,012
354,012
110,295
Cereals
Coefficient
(Std.)
0.0059
(0.006)
0.0062
(0.0049)
0.0046
(0.0048)
-0.0006
(0.0092)
Observations
692,679
692,679
692,679
242,184
Cheese
Coefficient
(Std.)
0.0109*
(0.0065)
0.0034
(0.0052)
0.0014
(0.0052)
-0.0058
(0.0075)
Observations
1,725,208
1,725,208
1,725,208
489,617
Cigarettes
Coefficient
(Std.)
0.0081
(0.0158)
0.0078
(0.014)
0.0067
(0.0136)
0.0083
(0.0133)
Observations
13,712
13,712
13,712
8,591
Cookies
Coefficient
(Std.)
0.0335***
(0.0044)
0.0253***
(0.004)
0.0229***
(0.0039)
0.0392***
(0.0076)
Observations
1,286,069
1,286,069
1,286,069
209,459
Crackers
Coefficient
(Std.)
0.0493***
(0.0076)
0.0364***
(0.0072)
0.0339***
(0.0072)
0.0446***
(0.0087)
Observations
448,590
448,590
448,590
81,601
Dish
Detergent
Coefficient
(Std.)
0.0292***
(0.0071)
0.0276***
(0.0059)
0.0232***
(0.0058)
0.0329***
(0.0087)
Observations
374,776
374,776
374,776
89,534
Fabric
Softener
Coefficient
(Std.)
0.0126
(0.0091)
0.0197***
(0.007)
0.0152**
(0.0067)
0.0312**
(0.0134)
Observations
357,352
357,352
357,352
96,359
Front-End-
Candies
Coefficient
(Std.)
-0.0161
(0.0098)
-0.0004
(0.0085)
-0.0006
(0.0084)
0.0032
(0.006)
Observations
471,213
471,213
471,213
140,179
Frozen
Dinners
Coefficient
(Std.)
0.0587***
(0.0068)
0.0516***
(0.0054)
0.0519***
(0.0055)
0.0751***
(0.0101)
Observations
443,557
443,557
443,557
58,225
44
Table D1. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0186***
(0.0025)
0.0272***
(0.0026)
0.0288***
(0.0025)
0.0518***
(0.0058)
Observations
1,771,958
1,771,958
1,771,958
318,555
Frozen Juices
Coefficient
(Std.)
0.0203***
(0.0074)
0.0174***
(0.0065)
0.013**
(0.0065)
0.0597***
(0.0086)
Observations
627,846
627,846
627,846
140,924
Grooming
Products
Coefficient
(Std.)
0.0392***
(0.0035)
0.0364***
(0.0033)
0.0349***
(0.0033)
0.0493***
(0.0076)
Observations
607,229
607,229
607,229
84,669
Laundry
Detergents
Coefficient
(Std.)
-0.0072
(0.0058)
0.0049
(0.0048)
0.0019
(0.0048)
0.0216***
(0.0094)
Observations
557,386
557,386
557,386
133,678
Oatmeal
Coefficient
(Std.)
-0.0021
(0.0111)
-0.0071
(0.0093)
-0.0075
(0.0089)
0.0081
(0.009)
Observations
153,883
153,883
153,883
56,264
Paper Towels
Coefficient
(Std.)
0.0293
(0.0236)
0.0285
(0.0193)
0.0264
(0.0187)
0.0382*
(0.0196)
Observations
229,649
229,649
229,649
48,847
Refrigerated
Juices
Coefficient
(Std.)
-0.0034
(0.0082)
-0.0012
(0.0067)
-0.0048
(0.0065)
0.0223***
(0.008)
Observations
763,905
763,905
763,905
150,388
Shampoos
Coefficient
(Std.)
0.029***
(0.0023)
0.0268***
(0.0022)
0.0231***
(0.0021)
0.0306***
(0.0059)
Observations
605,146
605,146
605,146
60,380
Snack
Crackers
Coefficient
(Std.)
0.0367***
(0.006)
0.0306***
(0.0055)
0.0273***
(0.0053)
0.0563***
(0.0092)
Observations
758,707
758,707
758,707
128,389
Soaps
Coefficient
(Std.)
0.0139***
(0.0031)
0.0134***
(0.0029)
0.0117***
(0.0029)
0.046***
(0.0047)
Observations
4,147,187
4,147,187
4,147,187
304,352
Soft Drinks
Coefficient
(Std.)
0.0075
(0.0144)
0.0101
(0.0109)
0.0071
(0.0106)
0.035***
(0.0104)
Observations
297,007
297,007
297,007
83,454
Toothbrushes
Coefficient
(Std.)
0.0291***
(0.0065)
0.0275***
(0.0066)
0.023***
(0.0062)
0.0303**
(0.0123)
Observations
274,744
274,744
274,744
38,861
Toothpastes
Coefficient
(Std.)
0.0175***
(0.0063)
0.0177***
(0.0054)
0.0147***
(0.0055)
0.0456***
(0.01)
Observations
567,725
567,725
567,725
84,935
Average coefficients
0.0181
0.0171
0.0149
0.0308
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 10¢, and 0 otherwise. The main independent variable is the log of the average sales volume of product i in
store s over the 52 weeks preceding time t. Column 1 reports the results of the baseline regression that includes only
the log of the average sales volume and the fixed effects for months, years, stores, and products. In column 2, we add
the following controls: the log of the average price, the log of the absolute change in the wholesale price, and a control
for sale- and bounce-back prices, which we identify using a sales filter algorithm. In column 3, we add a dummy for
9-ending prices as an additional control. In column 4, we focus on regular prices by excluding the sale- and bounce-
back prices. We estimate separate regressions for each product category, clustering the errors by product. * p < 10%,
** p < 5%, *** p < 1%
45
Appendix E. Adding Dominick’s pricing zones
According to Dominick’s data manual, Dominick’s employed 16 price zones. Thus,
we can use the zones as a proxy for the competition level.
We, therefore, incorporate the data on pricing zones and re-estimate regressions
similar to the ones that we report in Table 3 in the paper. The regressions take the form,
, , , , ,
,,
ln( )
i s t i s i s t
t t s i i s t
small price change average sales volume
month year u
X
(E1)
where small price change is a dummy that equals 1 if a price change of product i in store
s at time t is less or equal to 10¢, and 0 otherwise. The average sales volume is the
average sales volume of product i in store s over the 52 weeks preceding week t. X is a
matrix of other control variables. Month and year are fixed effects for the month and the
year of the price change.
and
are fixed effects for stores and products,
respectively, and u is an i.i.d error term. We estimate separate regressions for each
product category, clustering the errors by product.
The figures in Table E1 are the coefficients of the log of the average sales volume. In
column 1, the only control variables are the log of the average sales volume, and the
dummies for months, years, stores, and products. We find that 27 of the 29 coefficients of
the log of the average sales volume are positive. 15 of the 27 are statistically significant,
and 4 more are marginally significant. The average coefficient is 0.014, suggesting that a
1% increase in the sales volume is associated with a 1.4% increase in the likelihood of a
small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, a control for sale- and bounce-back prices (which we
identify using the sales filter algorithm of Fox and Syed 2016), and Dominick’s pricing
zone. We find that 27 of the 29 coefficients are positive. 14 of the positive coefficients
are statistically significant, and one more is marginally significant. The average
coefficient is 0.010, suggesting that a 1% increase in the sales volume is associated with a
1.0% increase in the likelihood of a small price change.
In column 3, we add a control for 9-ending prices. We find that 27 of the 29
coefficients are positive. 14 of the 29 are statistically significant, and two more are
46
marginally significant. The average coefficient is 0.010, suggesting that a 1% increase in
the sales volume is associated with a 1.0% increase in the likelihood of a small price
change.
As a further control for the effects of sales on the results, in column 4 we focus on
regular prices by excluding all sale- and bounce-back prices. When we focus on regular
prices, we find that 27 of the 29 coefficients are positive. 18 are statistically significant,
and 5 more are marginally significant. The average coefficient is 0.020, suggesting that a
1% increase in the sales volume is associated with a 2.0% increase in the likelihood of a
small price change.
Thus, adding a control for pricing zones does not change our main results. The
correlation between small price changes and sales volume holds in all 29 product
categories.
47
Table E1. Category-level regressions of small price changes and sales volume,
controlling for Dominick’s pricing zones
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0169***
(0.004)
0.0128***
(0.0038)
0.0126***
(0.0038)
0.0133***
(0.0079)
Observations
74,451
74,451
74,451
24,729
Bath Soap
Coefficient
(Std.)
0.0099
(0.0128)
0.0059
(0.013)
0.0058
(0.0126)
-0.0267
(0.0256)
Observations
6,650
6,650
6,650
1,466
Bathroom
Tissues
Coefficient
(Std.)
0.0479***
(0.0087)
0.0203**
(0.0084)
0.02**
(0.0083)
0.0349***
(0.0098)
Observations
56,458
56,458
56,458
19,285
Beer
Coefficient
(Std.)
0.002***
(0.0006)
0.0043***
(0.0007)
0.0043***
(0.0007)
0.018***
(0.0055)
Observations
187,691
187,691
187,691
12,080
Bottled Juice
Coefficient
(Std.)
0.0235***
(0.0079)
0.0187***
(0.007)
0.0188***
(0.007)
0.0333***
(0.0091)
Observations
224,857
224,857
224,857
60,015
Canned Soup
Coefficient
(Std.)
-0.0023
(0.0091)
-0.004
(0.0088)
-0.0012
(0.0086)
0.0129*
(0.0072)
Observations
233,779
233,779
233,779
95,310
Canned Tuna
Coefficient
(Std.)
0.0092
(0.0065)
-0.0006
(0.0057)
-0.0008
(0.0057)
0.0128
(0.0083)
Observations
112,629
112,629
112,629
31,922
Cereals
Coefficient
(Std.)
0.0051
(0.0065)
0.0049
(0.0063)
0.005
(0.0063)
0.0221***
(0.0071)
Observations
141,087
141,087
141,087
72,789
Cheese
Coefficient
(Std.)
0.0069*
(0.0038)
0.0066**
(0.0033)
0.0063*
(0.0033)
0.0124***
(0.0046)
Observations
357,679
357,679
357,679
92,758
Cigarettes
Coefficient
(Std.)
0.0044
(0.0051)
0.0021
(0.0049)
0.0022
(0.0048)
0
(0.0055)
Observations
24,553
24,553
24,553
20,692
Cookies
Coefficient
(Std.)
0.0084***
(0.0019)
0.0074***
(0.002)
0.0073***
(0.0019)
0.0063*
(0.0036)
Observations
317,932
317,932
317,932
66,087
Crackers
Coefficient
(Std.)
0.0009
(0.0033)
0.0007
(0.0032)
0.001
(0.0032)
0.0114*
(0.0066)
Observations
115,658
115,658
115,658
24,771
Dish
Detergent
Coefficient
(Std.)
0.0295***
(0.0068)
0.0241***
(0.006)
0.0244***
(0.0058)
0.0261***
(0.0058)
Observations
85,222
85,222
85,222
26,735
Fabric
Softener
Coefficient
(Std.)
0.0147**
(0.0069)
0.0028
(0.0057)
0.0033
(0.0057)
0.0233***
(0.0078)
Observations
85,337
85,337
85,337
27,488
Front-End-
Candies
Coefficient
(Std.)
-0.004
(0.0043)
-0.0044
(0.0034)
-0.0043
(0.0034)
-0.0005
(0.0032)
Observations
148,200
148,200
148,200
77,323
Frozen
Dinners
Coefficient
(Std.)
0.049***
(0.007)
0.0414***
(0.0062)
0.0431***
(0.0062)
0.0751***
(0.0104)
Observations
52,893
52,893
52,893
12,287
48
Table E1. (Cont.)
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 10¢, and 0 otherwise. The main independent variable is the log of the average sales volume of product i in
store s over the 52 weeks preceding time t . Column 1 reports the results of the baseline regression that includes only
the log of the average sales volume and the fixed effects for months, years, stores, and products. In column 2, we add
the following controls: the log of the average price, the log of the absolute change in the wholesale price, a control for
sale- and bounce-back prices, which we identify using a sales filter algorithm, and the pricing zone of the store. In
column 3, we add a dummy for 9-ending prices as an additional control. In column 4, we focus on regular prices by
excluding the sale- and bounce-back prices. We estimate separate regressions for each product category, clustering the
errors by product. * p < 10%, ** p < 5%, *** p < 1%.
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0192***
(0.0027)
0.0186***
(0.0025)
0.0188***
(0.0025)
0.0247***
(0.0039)
Observations
345,223
345,223
345,223
117,044
Frozen Juices
Coefficient
(Std.)
0.0134*
(0.0073)
0.0113*
(0.0068)
0.0124*
(0.0066)
0.0213**
(0.0087)
Observations
118,582
118,582
118,582
40,517
Grooming
Products
Coefficient
(Std.)
0.0097***
(0.0033)
0.0111***
(0.0033)
0.0113***
(0.0033)
0.0166
(0.011)
Observations
101,944
101,944
101,944
22,102
Laundry
Detergents
Coefficient
(Std.)
0.0213***
(0.0047)
0.0128***
(0.0039)
0.0131***
(0.0039)
0.0175***
(0.0057)
Observations
121,566
121,566
121,566
42,121
Oatmeal
Coefficient
(Std.)
0.0154
(0.0124)
0.0086
(0.0121)
0.0067
(0.0115)
0.059***
(0.0115)
Observations
25,523
25,523
25,523
13,605
Paper Towels
Coefficient
(Std.)
0.0275***
(0.0156)
0.021
(0.0178)
0.0225
(0.0177)
0.0325**
(0.016)
Observations
48,199
48,199
48,199
9,243
Refrigerated
Juices
Coefficient
(Std.)
0.0136*
(0.0077)
0.0062
(0.0079)
0.0063
(0.0077)
0.0253**
(0.0121)
Observations
108,965
108,965
108,965
23,705
Shampoos
Coefficient
(Std.)
0.0098***
(0.0025)
0.0104***
(0.0025)
0.0104***
(0.0025)
0.0232***
(0.008)
Observations
88,193
88,193
88,193
16,099
Snack
Crackers
Coefficient
(Std.)
0.0013
(0.0029)
0.0033
(0.0028)
0.0033
(0.0028)
0.0153***
(0.0052)
Observations
176,527
176,527
176,527
38,123
Soaps
Coefficient
(Std.)
0.0237***
(0.0088)
0.013
(0.0082)
0.0165**
(0.0081)
0.0509***
(0.0117)
Observations
56,725
56,725
56,725
16,882
Soft Drinks
Coefficient
(Std.)
0.0087***
(0.0022)
0.013***
(0.0018)
0.0121***
(0.0018)
0.0078**
(0.0034)
Observations
243,837
243,837
243,837
49,989
Toothbrushes
Coefficient
(Std.)
0.013***
(0.0046)
0.0098**
(0.0047)
0.0091**
(0.0046)
0.019*
(0.0102)
Observations
52,185
52,185
52,185
13,695
Toothpastes
Coefficient
(Std.)
0.0007
(0.0039)
0.0001
(0.0038)
0.0003
(0.0038)
0.0052
(0.0082)
Observations
100,845
100,845
100,845
28,039
Average coefficients
0.0138
0.0097
0.0100
0.0204
49
Appendix F. Robustness of the Product-level regressions of the % of small price changes
and sales volume
In the paper, we study the correlation between small price changes and sales volume
at the product level using regressions that have only the sales volume as the independent
variable. This can raise concerns that the results may be driven by differences between
the stores rather than by differences in the sales volume.
To mitigate this concern, we augment the data with demographic information about
consumers living in the neighborhood of each store, including their median income, the
share of minorities, and the share of unemployed. To control for local competition, we
also add a control for the pricing zone of each store, using pricing zone indicators
included in Dominick’s data.
We estimate for each product in each category an OLS regression with robust
standard errors. The dependent variable is the share of small price changes for the
product in each store. The independent variable is the average sales volume of the
product in each store, the median income, the share of minorities, the share of
unemployed, and the stores’ pricing zone.
As we do in the paper, we use observations on price changes only if we observe the
price in both weeks t and t + 1 and the post change price remained unchanged for at least
2 weeks. The estimation results are summarized in Table F1. Column 1 presents for each
product category, the average of the estimated coefficients. Column 2 presents the total
number of coefficients. Column 3 presents the percentage of the positive coefficients.
Column 4 presents the number of statistically significant coefficients. Column 5 presents
the percentage of positive and statistically significant coefficients out of the total number
of statistically significant coefficients.
According to the figures in the table, the average coefficients are positive in 28 of the
29 product categories. The only exception is in the highly regulated cigarettes category.
Further, in all categories, the number of positive coefficients far exceeds the number of
negative coefficients. On average, 72.19% of all the coefficients are positive.
Focusing on statistically significant coefficients, we find a far greater number of
positive coefficients that are significant than negative coefficients that are significant. On
average, 87.71% of all the statistically significant coefficients are positive. In other
50
words, for the overwhelming majority of the individual products in our sample, we find a
positive relationship between sales volume and the share of small price changes.
As another test, we estimate linear probability model (LPM) regressions with robust
standard errors, instead of regressions at the store level. In other words, we estimate:
(F1)
where small price change is a dummy that equals 1 if a price change of product i in store
s in week t is less or equal to 10¢, and 0 otherwise. The average sales volume is the
average sales volume of product i in store s over the sample period.
1
X is a matrix of
other control variables.
We estimate a separate regression for each product in each category, conditional on it
having at least 30 price changes and at least 1 small price change over the sample period.
2
Table F2 reports the estimation results of regressions in which the X matrix is empty. We
find that in all but the toothpaste category, the average coefficient is positive.
Furthermore, on average, 72.19% of the coefficients are positive. When we focus on the
positive and statistically significant coefficients, we find that, on average, 91.96% of the
coefficients are positive.
Table F3 reports the estimation results of regressions in which the X matrix includes
the following independent variables: the log of the average price, the log of the absolute
change in the wholesale price, a dummy for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016), and a dummy for 9-
ending prices.
We find that 22 of the 28 average coefficients are positive. When we focus on all the
coefficients, we find that on average, 67.61% of the coefficients in a category are
positive. When we focus on positive and statistically significant coefficients, we find that,
1
In calculating the average sales volume, we need to account for missing observations, because a missing observation
in week t implies that the product was either out of stock or had 0 sales on that week. Thus, averaging over the
available observations can lead to an upward bias for products that are sold in small numbers. Therefore, for each
product in each store, we calculate the average by first determining the total number of units sold over all available
observations. We then identify the first and last week for which we have observations, and calculate the average for
each product-store as
. The resulting figure is smaller than we would obtain if we averaged over all
available observations (which would not include observations on weeks with 0 sales).
2
Prices and price changes in the cigarettes category were heavily regulated during the sample period. Consequently, we
have no product-store combination for which we have 30 or more price changes over the sample period in the
cigarettes’ category.
51
on average, 89.57% of the coefficients are positive.
We therefore conclude that changing the estimation method does not change the
conclusions we report in the paper. There is a positive correlation at the product level
between the likelihood of a small price change and the sales volume.
52
Table F1. Product-level regressions of the % of small price changes and sales volume by
categories, including controls
Product
Category
Average coefficient
(1)
No. of
coefficients
(2)
% positive
coefficients
(3)
No. of significant
coefficients
(4)
% positive and
significant
coefficients
(5)
Analgesics
0.025
212
74.53%
48
97.92%
Bath Soaps
0.036
33
72.73%
8
100.00%
Bathroom tissues
0.045
100
75.00%
37
89.19%
Beers
0.018
202
89.11%
71
98.59%
Bottled juices
0.042
370
73.24%
115
86.96%
Canned soups
0.032
348
70.98%
112
86.61%
Canned tuna
0.025
181
59.67%
61
70.49%
Cereals
0.039
345
68.41%
110
81.82%
Cheese
0.033
474
70.68%
151
92.72%
Cigarettes
-0.016
106
50.94%
9
0.00%
Cookies
0.034
666
74.77%
213
94.37%
Crackers
0.040
212
79.72%
72
98.61%
Dish detergents
0.032
199
69.85%
46
91.30%
Fabric softeners
0.029
226
70.80%
52
94.23%
Front end candies
0.033
274
63.50%
56
91.07%
Frozen dinners
0.056
215
84.19%
77
96.10%
Frozen entrees
0.044
671
82.41%
270
97.78%
Frozen juices
0.045
142
79.58%
57
96.49%
Grooming products
0.008
528
68.75%
89
94.38%
Laundry detergents
0.011
406
63.30%
74
77.03%
Oatmeal
0.042
69
71.01%
13
92.31%
Paper towels
0.045
90
73.33%
37
81.08%
Refrigerated juices
0.031
176
68.75%
63
82.54%
Shampoos
0.019
608
70.39%
97
97.94%
Snack crackers
0.043
282
77.66%
89
95.51%
Soaps
0.032
216
68.52%
43
81.40%
Soft drinks
0.030
897
76.25%
285
96.84%
Toothbrushes
0.024
202
80.20%
45
93.33%
Toothpastes
0.013
336
65.18%
61
86.89%
Average
0.031
303
72.19%
85
87.71%
Notes: Results of product-level regression. The dependent variable in all regressions is the % of small price changes at
each store. For each product category, column 1 presents the average estimated coefficients of the average sales volumes.
The regressions also include controls for the median income, the share of ethnic minorities, the unemployment rate, and
the pricing zone of the store. Column 2 presents the total number of coefficients. Column 3 presents the % of positive
coefficients out of all coefficients. Column 4 presents the total number of coefficients that are statistically significant at
the 5% level. Column 5 presents the % of coefficients that are positive and statistically significant, at the 5% level.
53
Table F2. Product-level regressions of the % of small price changes and sales volume by
categories, using LPM
Product
Category
Average coefficient
(1)
No. of
coefficients
(2)
% positive
coefficients
(3)
No. of significant
coefficients
(4)
% positive and
significant
coefficients
(5)
Analgesics
0.055
24
70.83%
2
100.00%
Bath Soaps
0.290
1
100.00%
0
−
Bathroom tissues
0.032
23
86.96%
15
86.67%
Beers
0.007
68
72.06%
17
100.00%
Bottled juices
0.044
98
76.53%
43
90.70%
Canned soups
0.049
100
81.00%
40
87.50%
Canned tuna
0.012
37
56.76%
14
42.86%
Cereals
0.060
59
76.27%
28
92.86%
Cheese
0.027
161
83.23%
64
95.31%
Cigarettes
−
0
−
0
−
Cookies
0.047
109
79.82%
34
100.00%
Crackers
0.236
51
88.24%
24
100.00%
Dish detergents
0.024
30
70.00%
15
93.33%
Fabric softeners
0.037
21
80.95%
9
100.00%
Front end candies
0.121
41
95.12%
29
100.00%
Frozen dinners
0.347
32
93.75%
14
100.00%
Frozen entrees
0.040
177
87.57%
97
97.94%
Frozen juices
0.039
66
89.39%
37
91.89%
Grooming products
0.009
30
53.33%
1
100.00%
Laundry detergents
0.016
18
61.11%
2
100.00%
Oatmeal
0.298
15
80.00%
0
−
Paper towels
0.012
21
66.67%
10
60.00%
Refrigerated juices
0.007
57
56.14%
29
68.97%
Shampoos
0.075
11
54.55%
0
−
Snack crackers
0.036
76
88.16%
37
100.00%
Soaps
0.027
17
64.71%
0
−
Soft drinks
0.031
285
72.63%
103
99.03%
Toothbrushes
0.034
22
63.64%
1
100.00%
Toothpastes
-0.245
51
72.55%
10
100.00%
Average
0.063
59
75.78%
23
91.96%
Notes: The table reports the estimation results of product-level LPM regressions. The dependent variable in all regressions
is a dummy for price small price changes ( . The main independent variable is the log of the sales volume. For
each product category, column 1 presents the average estimated coefficients of the average sales volumes. Column 2
presents the total number of coefficients. Column 3 presents the % of positive coefficients out of all coefficients. Column
4 presents the total number of coefficients that are statistically significant at the 5% level. Column 5 presents the % of
coefficients that are positive and statistically significant, at the 5% level.
54
Table F3. Product-level regressions of the % of small price changes and sales volume by
categories, using LPM with extra controls
Product
Category
Average coefficient
(1)
No. of
coefficients
(2)
% positive
coefficients
(3)
No. of significant
coefficients
(4)
% positive and
significant
coefficients
(5)
Analgesics
0.078
24
62.50%
1
100.00%
Bath Soaps
-0.044
1
0.00%
0
−
Bathroom tissues
-0.010
23
69.57%
5
80.00%
Beers
-0.001
69
57.97%
8
100.00%
Bottled juices
0.019
98
71.43%
14
92.86%
Canned soups
0.025
100
84.00%
13
100.00%
Canned tuna
0.004
37
64.86%
5
40.00%
Cereals
0.052
59
77.97%
18
100.00%
Cheese
0.008
161
73.91%
38
92.11%
Cigarettes
−
0
−
0
−
Cookies
-0.060
109
79.82%
25
100.00%
Crackers
0.071
50
88.00%
20
100.00%
Dish detergents
0.025
30
83.33%
9
100.00%
Fabric softeners
0.090
21
100.00%
9
100.00%
Front end candies
0.015
41
63.41%
9
100.00%
Frozen dinners
0.205
32
78.13%
6
100.00%
Frozen entrees
0.023
177
80.23%
43
93.02%
Frozen juices
0.023
66
74.24%
22
90.91%
Grooming products
-0.016
30
46.67%
1
100.00%
Laundry detergents
0.009
18
61.11%
2
100.00%
Oatmeal
0.363
15
66.67%
0
−
Paper towels
-0.015
21
33.33%
6
16.67%
Refrigerated juices
0.004
57
66.67%
27
70.37%
Shampoos
0.074
11
63.64%
0
−
Snack crackers
0.044
76
85.53%
33
100.00%
Soaps
0.065
17
64.71%
3
66.67%
Soft drinks
0.185
286
66.78%
60
96.67%
Toothbrushes
0.012
22
54.55%
1
100.00%
Toothpastes
0.053
50
74.00%
13
100.00%
Average
0.046
59
67.61%
13
89.57%
Notes: The table reports the estimation results of product-level LPM regressions. The dependent variable in all regressions
is a dummy for price small price changes ( . The main independent variable is the log of the sales volume. The
regression also includes the following independent variables: the log of the average price, the log of the absolute change
in the wholesale price, a control for sale- and bounce-back prices, which we identify using a sales filter algorithm, and a
dummy for 9-ending prices as an additional control. For each product category, column 1 presents the average estimated
coefficients of the average sales volumes. Column 2 presents the total number of coefficients. Column 3 presents the % of
positive coefficients out of all coefficients. Column 4 presents the total number of coefficients that are statistically
significant at the 5% level. Column 5 presents the % of coefficients that are positive and statistically significant, at the 5%
level.
55
Appendix G. Robustness: sales volume, revenue, and small price changes
In the paper, we estimate category-level regressions of small price changes where the
main independent variables are sales volume and revenue. In this appendix, we conduct
two sets of robustness tests. First, we add further controls and estimate the category-level
regressions again. Second, because the correlation between sales volume and revenue at
the category level is high, the results of category-level regressions could be suspect. We,
therefore, pool the data from all categories together and re-estimate the regressions using
the pooled data.
In Tables G1 and G2, we present the results of the category-level regression
estimations. The regressions we estimate are of the following form:
(G1)
where small price change is a dummy that equals 1 if a price change of product i in store
s at time t is less or equal to 10¢, and 0 otherwise. The average sales volume is the
average sales volume of product i in store s over the sample period. The average revenue
is the average revenue of product i in store s over the sample period. X is a matrix of
other control variables. Month and year are fixed effects for the month and the year of the
price change.
and
are fixed effects for stores and products, respectively, and u is
an i.i.d error term. We estimate separate regressions for each product category, clustering
the errors by product. As we do in the paper, we use observations on price changes only
if we observe the price in both week t and t+1 and the post change price remained
unchanged for at least 2 weeks.
The coefficient columns in the sales volume and the revenue panels of Table G1 give
the coefficients of sales volume and revenue, respectively in a regression that also
includes percentage changes in the wholesale price and a dummy for sale- and bounce-
back prices as control variables.
3
This does not change the results we report in the paper.
22 of the sales volume coefficients are positive. 14 of the coefficients are statistically
3
We do not add the log of the average price because the log of the price plus the log of the sales volume equals the log
of the revenue, leading to a perfect multicollinearity.
56
significant. 4 of the negative coefficients are statistically significant. Of the revenue
coefficients, 21 are negative, and all of them are statistically significant.
The coefficient columns in the sales volume and the revenue panels of Table G2,
present the coefficients of sales volume and revenue, respectively in a regression in
which we also include a dummy for 9-ending prices. We find that 22 of the sales volume
coefficients are statistically significant. Of the 22 positive coefficients, 14 are statistically
significant. Of the revenue coefficients, 18 of the coefficients are negative, all of which
are statistically significant.
Thus, including more controls does not change the conclusions we derive in the
paper. The revenue seems to be correlated to small price changes mostly through the
sales volume. The effect of the price, holding sales volume constant seems to be mostly
negative.
However, the results at the category level are suspect because of the strong
correlation between sales volume and revenue. In the paper, we show that the average
correlation at the category level is 0.85. The high correlation at the category level is due
to the relatively low within-category variation in prices. To attenuate this concern, we
pool the data from all categories together. Since the between-categories variation in
prices is higher than the within-category variation, we find that in the pooled data, the
correlation between sales volume and revenue is 0.70.
Table G3 presents the results of regressions similar to G1, to which we also add fixed
effects for the categories. Column 1 gives the results of a regression that includes only the
sales volume and the revenue as independent variables. The coefficient of the sales
volume, 0.42, is positive and statistically significant, whereas the coefficient of the
revenue, −0.40, is negative and statistically significant.
In column 2, we add controls for percentage changes in the wholesale price, and for
sale- and bounce-back prices. The coefficient of the sales volume, 0.38, is positive and
statistically significant, whereas the coefficient of the revenue, −0.36, is negative and
statistically significant.
In column 3, we also add a dummy for 9-ending prices. The coefficient of the sales
volume, 0.02, remains positive and statistically significant, whereas the coefficient of the
revenue, −0.61, remains negative and statistically significant.
57
Finally, in column 4, we remove sale prices and focus on regular prices. The
coefficient of sales volume, 0.03, is positive and significant. The coefficient of revenue,
−0.53, is negative and statistically significant.
Thus, also when we estimate the regressions using the pooled data, we find a positive
correlation between sales volume and small price changes. We also find that when we
hold the sales volume constant, the correlation between revenue and small price changes
is negative.
As an alternative test of the role of revenue, we redefine the average revenue as the
product of the average sales volume and the average price. Both are defined the same
way as in the paper. We then estimate
(G2)
where is the product of the average sales volume and the average
price of product offered at store , and the other variables are defined as above. As
above, we estimate a series of category-level regressions.
Table G4 gives the estimation results. In column 1, the only control variables are the
log of the average sales volume, and the dummies for months, years, stores, and products.
We find that 28 of the 29 coefficients of the log of the average revenue are positive. All
the positive coefficients are statistically significant. The average coefficient is 0.017,
suggesting that a 1% increase in the average revenue is associated with a 1.7% increase in
the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices (which we
identify using the sales filter algorithm of Fox and Syed 2016). We find that all 29
coefficients are positive. 28 of the positive coefficients are statistically significant, and
one more is marginally significant. The average coefficient is 0.015, suggesting that a 1%
increase in the average revenue is associated with a 1.5% increase in the likelihood of a
small price change.
In column 3, we add a control for 9-ending prices. We find that all 29 coefficients
are positive. 28 of the positive coefficients are statistically significant, and one more is
58
marginally significant. The average coefficient is 0.015, suggesting that a 1% increase in
the average revenue is associated with a 1.5% increase in the likelihood of a small price
change.
As a further control for the effects of sales on the estimation results, in column 4 we
focus on regular prices by excluding all sale- and bounce-back prices. When we focus on
regular prices, we find that all 29 coefficients are positive and statistically significant.
The average coefficient is 0.029, suggesting that a 1% increase in the average revenue is
associated with a 2.9% increase in the likelihood of a small price change.
Thus, the finding of the positive correlation between revenue and the likelihood of
small price changes is robust. However, our previous results suggest that this correlation
holds because of the sales volume component rather than the price component of the
revenue. Indeed, we also include the average price as a control variable in this regression.
If the correlation between the likelihood of a small price change and revenue were to
work mainly through the price component of the revenue, then we would expect that the
coefficient of the average price in columns 2–4 would be positive and statistically
significant, while the average revenue coefficient would be close to 0 and statistically
insignificant.
59
Table G1. Regressions with sales volume and revenue, with extra controls
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change. The
dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less or equal
to 10¢, and 0 otherwise. The main independent variables are the log of the average sales volume of product i in store s over
the sample period and the log of the average revenue of product i in store s over the sample period. The regressions also
include the following independent variables: percentage changes in the wholesale price and a dummy for sale and bounce-
back prices, as well as fixed effects for years, months, stores, and products. We estimate separate regressions for each
product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
Category
Sales Volume
Revenue
No. of
Observations
Coefficient
Std.
Coefficient
Std.
Analgesics
0.2405***
0.0464
-0.223***
0.0467
144,461
Bath Soap
-0.3004**
0.1098
0.3289***
0.1099
15,295
Bathroom Tissues
0.4332***
0.1270
-0.4187***
0.1258
149,441
Beer
-0.0613**
0.0258
0.0764***
0.0257
290,620
Bottled Juice
0.69***
0.0983
-0.6651***
0.0982
496,557
Canned Soup
0.1141
0.0688
-0.1027
0.0690
495,543
Canned Tuna
0.4883***
0.1066
-0.4736***
0.1071
213,043
Cereals
0.1056**
0.0400
-0.0901**
0.0406
357,120
Cheese
0.3698***
0.1062
-0.3583***
0.1067
796,150
Cigarettes
-0.3952***
0.0589
0.405***
0.0588
36,157
Cookies
-0.0207
0.0222
0.0431*
0.0224
688,761
Crackers
0.1497***
0.0523
-0.1203***
0.0527
245,185
Dish Detergent
0.4543***
0.1332
-0.4291***
0.1329
189,633
Fabric Softener
0.8047***
0.1924
-0.7907***
0.1932
181,056
Front-End-Candies
0.3188***
0.0481
-0.3113***
0.0490
278,853
Frozen Dinners
0.0474
0.0460
-0.0106
0.0456
203,191
Frozen Entrees
-0.0026
0.0174
0.0278
0.0170
864,832
Frozen Juices
0.0946
0.0527
-0.075
0.0534
308,817
Grooming Products
0.0361
0.0335
-0.0155
0.0341
269,873
Laundry Detergents
0.251***
0.0537
-0.2413***
0.0532
272,765
Oatmeal
-0.0251
0.0212
0.0415*
0.0230
79,983
Paper Towels
0.711***
0.1851
-0.6752***
0.1856
116,204
Refrigerated Juices
0.0277
0.0606
-0.0063
0.0616
306,865
Shampoos
0.0178
0.0159
0.0017
0.0158
261,778
Snack Crackers
0.0477
0.0817
-0.0198
0.0826
398,665
Soap
0.4612***
0.1564
-0.4379***
0.1567
152,379
Soft Drinks
0.4933***
0.0442
-0.4694***
0.0435
1,350,618
Toothbrushes
0.0416
0.0401
-0.0215
0.0401
125,380
Toothpastes
-0.0764**
0.0344
0.0894***
0.0345
264,317
Average
0.1902
0.0717
-0.1704
0.0719
329,432
60
Table G2. Regressions with sales volume and revenue, with extra controls, including a
control for 9-ending prices
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change. The
dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less or equal
to 10¢, and 0 otherwise. The main independent variables are the log of the average sales volume of product i in store s over
the sample period and the log of the average revenue of product i in store s over the sample period. The regressions also
include the following independent variables: percentage changes in the wholesale price, a dummy for sale and bounce-back
prices, and a dummy for 9-ending prices, as well as fixed effects for years, months, stores, and products. We estimate
separate regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
Category
Sales Volume
Revenue
No. of
Observations
Coefficient
Std.
Coefficient
Std.
Analgesics
0.2366***
0.0456
-0.2193***
0.0459
144,461
Bath Soap
-0.3045***
0.1103
0.3337***
0.1103
15,295
Bathroom Tissues
0.4045***
0.1253
-0.3894***
0.1241
149,441
Beer
-0.0609**
0.0257
0.0759***
0.0256
290,620
Bottled Juice
0.682***
0.0931
-0.6576***
0.0930
496,557
Canned Soup
0.0983
0.0699
-0.0842
0.0701
495,543
Canned Tuna
0.482***
0.1057
-0.4676***
0.1062
213,043
Cereals
0.104***
0.0400
-0.0885**
0.0406
357,120
Cheese
0.3678***
0.1061
-0.3564***
0.1066
796,150
Cigarettes
-0.3872***
0.0587
0.397***
0.0586
36,157
Cookies
-0.0189
0.0218
0.0416*
0.0220
688,761
Crackers
0.1437***
0.0520
-0.1139**
0.0524
245,185
Dish Detergent
0.4572***
0.1321
-0.4321***
0.1318
189,633
Fabric Softener
0.8009***
0.1920
-0.7866***
0.1929
181,056
Front-End-Candies
0.3019***
0.0483
-0.2942***
0.0491
278,853
Frozen Dinners
0.0337
0.0450
0.0061
0.0444
203,191
Frozen Entrees
-0.0045
0.0175
0.0305*
0.0171
864,832
Frozen Juices
0.0847
0.0533
-0.0644
0.0539
308,817
Grooming Products
0.0299
0.0333
-0.0091
0.0339
269,873
Laundry Detergents
0.25***
0.0534
-0.2398***
0.0530
272,765
Oatmeal
-0.0234
0.0207
0.04*
0.0226
79,983
Paper Towels
0.7135***
0.1868
-0.6772***
0.1873
116,204
Refrigerated Juices
0.0209
0.0595
0.0003
0.0604
306,865
Shampoos
0.0152
0.0159
0.0043
0.0159
261,778
Snack Crackers
0.0423
0.0820
-0.0142
0.0829
398,665
Soap
0.4744***
0.1522
-0.4501***
0.1527
152,379
Soft Drinks
0.4319***
0.0332
-0.409***
0.0327
1,350,618
Toothbrushes
0.0002
0.0398
0.0197
0.0398
125,380
Toothpastes
-0.0752**
0.0344
0.0882**
0.0345
264,317
Average
0.1828
0.0708
0.1626-
0.0710
329,432
61
Table G3. Regressions with sales volume and revenue, using a pooled dataset
(1)
(2)
(3)
(4)
Log of sales
volume
0.42***
(0.024)
0.38***
(0.025)
0.02***
(0.001)
0.03***
(0.001)
Log of
revenue
−0.40***
(0.024)
−0.36***
(0.025)
−0.61***
(0.016)
−0.53***
(0.029)
Observations
9,553,542
9,553,542
9,553,542
2,328,405
Notes: The table reports the results of pooled fixed effect regressions of the probability of a small price change. The
dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less or equal
to 10¢, and 0 otherwise. The main independent variables are the log of the average sales volume and the log of the revenue
of product i in store s over the sample period. Column 1 reports the results of the baseline regression that includes only the
log of the average sales volume, the log of the average revenue, and the fixed effects for months, years, categories, stores,
and products. In column 2, we add the following controls: the log of the average price, the log of the absolute change in the
wholesale price, a control for sale- and bounce-back prices (which we identify using a sales filter algorithm) and the
competition zone of the store. In column 3, we add a dummy for 9-ending prices as an additional control. In column 4, we
focus on regular prices by excluding the sale- and bounce-back prices. We estimate separate regressions for each product
category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
62
Table G4. Regression with the average revenue constructed as the average sales
volume times the average price
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0147***
(0.0023)
0.0114***
(0.0021)
0.0113***
(0.0021)
0.0193***
(0.0045)
Observations
144,461
144,461
144,461
44,950
Bath Soap
Coefficient
(Std.)
0.018***
(0.0049)
0.017***
(0.0047)
0.0174***
(0.0046)
0.0579***
(0.0119)
Observations
15,295
15,295
15,295
3,208
Bathroom
Tissues
Coefficient
(Std.)
0.0256***
(0.0057)
0.0134**
(0.0056)
0.0137***
(0.0056)
0.0334***
(0.0082)
Observations
149,441
149,441
149,441
47,041
Beer
Coefficient
(Std.)
0.0085***
(0.0009)
0.0114***
(0.0008)
0.0114***
(0.0008)
0.047***
(0.0045)
Observations
290,620
290,620
290,620
27,348
Bottled Juice
Coefficient
(Std.)
0.0207***
(0.0049)
0.0172***
(0.0041)
0.017***
(0.0042)
0.0239***
(0.0061)
Observations
496,557
496,557
496,557
133,714
Canned Soup
Coefficient
(Std.)
0.0117**
(0.0048)
0.01**
(0.0044)
0.0121***
(0.0043)
0.0132***
(0.0045)
Observations
495,543
495,543
495,543
176,235
Canned Tuna
Coefficient
(Std.)
0.0153***
(0.0042)
0.0126***
(0.0039)
0.0124***
(0.0038)
0.0197***
(0.0048)
Observations
213,043
213,043
213,043
64,161
Cereals
Coefficient
(Std.)
0.0162***
(0.0032)
0.0134***
(0.003)
0.0133***
(0.003)
0.0158***
(0.0039)
Observations
357,120
357,120
357,120
155,367
Cheese
Coefficient
(Std.)
0.0148***
(0.0025)
0.0084***
(0.0023)
0.0084***
(0.0023)
0.0109***
(0.003)
Observations
796,150
796,150
796,150
224,889
Cigarettes
Coefficient
(Std.)
0.0092**
(0.0028)
0.0095**
(0.0028)
0.0095**
(0.0028)
0.0084**
(0.0034)
Observations
36,157
36,157
36,157
30,262
Cookies
Coefficient
(Std.)
0.0208***
(0.0015)
0.0178***
(0.0014)
0.018***
(0.0014)
0.0368***
(0.0029)
Observations
688,761
688,761
688,761
132,488
Crackers
Coefficient
(Std.)
0.0291***
(0.0025)
0.0229***
(0.0022)
0.0232***
(0.0022)
0.0366***
(0.0055)
Observations
245,185
245,185
245,185
50,029
Dish
Detergent
Coefficient
(Std.)
0.029***
(0.0036)
0.0213***
(0.0032)
0.0212***
(0.0031)
0.0277***
(0.0037)
Observations
189,633
189,633
189,633
53,289
Fabric
Softener
Coefficient
(Std.)
0.0124***
(0.0037)
0.0088***
(0.0034)
0.0089***
(0.0034)
0.0258***
(0.0044)
Observations
181,056
181,056
181,056
56,234
Front-End-
Candies
Coefficient
(Std.)
-0.0016
(0.0033)
0.0045*
(0.0026)
0.0048***
(0.0026)
0.0088***
(0.0026)
Observations
278,853
278,853
278,853
111,635
Frozen
Dinners
Coefficient
(Std.)
0.0344***
(0.0028)
0.0288***
(0.0023)
0.0308***
(0.0023)
0.0597***
(0.0053)
Observations
203,191
203,191
203,191
37,527
63
Table G4. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0187***
(0.0016)
0.0187***
(0.0015)
0.0193***
(0.0015)
0.0361***
(0.0026)
Observations
864,832
864,832
864,832
213,545
Frozen Juices
Coefficient
(Std.)
0.0203***
(0.0041)
0.0156***
(0.0037)
0.0162***
(0.0035)
0.0269***
(0.0055)
Observations
308,817
308,817
308,817
87,919
Grooming
Products
Coefficient
(Std.)
0.0105***
(0.0015)
0.0134***
(0.0016)
0.0135***
(0.0016)
0.026***
(0.0046)
Observations
269,873
269,873
269,873
51,819
Laundry
Detergents
Coefficient
(Std.)
0.0125***
(0.0024)
0.008***
(0.0023)
0.0082***
(0.0023)
0.0173***
(0.0037)
Observations
272,765
272,765
272,765
85,184
Oatmeal
Coefficient
(Std.)
0.0238***
(0.0066)
0.0127**
(0.0058)
0.0129***
(0.0058)
0.0284***
(0.0082)
Observations
79,983
79,983
79,983
36,043
Paper Towels
Coefficient
(Std.)
0.025**
(0.0081)
0.0251***
(0.0082)
0.0254***
(0.0083)
0.0353***
(0.0081)
Observations
116,204
116,204
116,204
29,280
Refrigerated
Juices
Coefficient
(Std.)
0.0277***
(0.0041)
0.0179***
(0.0033)
0.0177***
(0.0033)
0.0272***
(0.0052)
Observations
306,865
306,865
306,865
72,031
Shampoos
Coefficient
(Std.)
0.0091***
(0.001)
0.0119***
(0.001)
0.0119***
(0.001)
0.0267***
(0.0031)
Observations
261,778
261,778
261,778
40,996
Snack
Crackers
Coefficient
(Std.)
0.0267***
(0.0028)
0.0234***
(0.0026)
0.0236***
(0.0026)
0.0434***
(0.0045)
Observations
398,665
398,665
398,665
78,581
Soaps
Coefficient
(Std.)
0.0234***
(0.0041)
0.0155***
(0.0037)
0.0162***
(0.0037)
0.0331***
(0.0058)
Observations
152,379
152,379
152,379
46,829
Soft Drinks
Coefficient
(Std.)
0.0099***
(0.0021)
0.0096***
(0.0021)
0.0099***
(0.0018)
0.0388***
(0.0028)
Observations
1,350,618
1,350,618
1,350,618
156,004
Toothbrushes
Coefficient
(Std.)
0.0129***
(0.0018)
0.0137***
(0.0018)
0.0137***
(0.0018)
0.0332***
(0.0047)
Observations
125,380
125,380
125,380
24,955
Toothpastes
Coefficient
(Std.)
0.0082***
(0.002)
0.0089***
(0.0016)
0.0088***
(0.0016)
0.0274***
(0.0046)
Observations
264,317
264,317
264,317
56,842
Average coefficients
0.0175
0.0146
0.0149
0.0291
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 15¢, and 0 otherwise. The main independent variable is the log of average sales volume of product i in store
s over the sample period × the average of the price of product i in store s over the sample period. Column 1 reports the
results of the baseline regression that includes only the log of average sales volume and the fixed effects for months,
years, stores, and products. In column 2, we add the following controls: the log of the average price, the log of the
absolute change in the wholesale price, and a control for sale- and bounce-back prices, which we identify using a sales
filter algorithm. In column 3, we add a dummy for 9-ending prices as an additional control. In column 4, we focus on
regular prices by excluding the sale- and bounce-back prices. We estimate separate regressions for each product
category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
64
Appendix H. Producers’ size and the robustness of the correlation between small
price changes and sales volumes
Bhattarai and Shoenle (2014) report that large producers, i.e., producers that sell a
large number of products, are more likely to have small price changes. Table H1 shows
for each of the categories, the % of small price changes by quartiles of producers’ size.
To find the producers’ size, in each category, we find the weekly average number of
products per producer. We then average over all weeks to get the average number of
products sold by each producer (Bhattarai and Shoenle, 2014).
We find that in our data, there is no clear pattern. Taking the average over all
categories, we find that there are 33.23%, 29.48%, 28.64%, and 28.54% small price
changes in the first, second, third, and fourth quartiles, respectively. Therefore, in our
data, we do not find a correlation between small price changes and producers’ size,
perhaps because in our data decisions on the timing of price changes are made by the
retailer rather than by the producers.
Nevertheless, we divide each category into quartiles by producers’ size and estimate:
(H1)
where small price change is a dummy that equals 1 if a price change of product i in store
s at time t is less or equal to 10¢, and 0 otherwise. As we do in the paper, we use
observations on price changes only if we observe the price in both weeks t and t + 1 and
the post change price remained unchanged for at least 2 weeks. The average sales volume
is the average sales volume of product i in store s over the sample period. Month and year
are fixed effects for the month and the year of the price change.
and
are fixed
effects for stores and products, respectively. u is an i.i.d error term.
In Table H2 we report the estimation results. We find that for the first two quartiles, 28
out the 29 coefficients are positive. In the first quartile, 25 of the positive coefficients are
statistically significant, and one more is marginally significant. In the second quartile, 24
of the positive coefficients are statistically significant.
In the third quartile, all 29 of the coefficients are statistically significant. 27 of them
are statistically significant, and 2 more are marginally significant. In the fourth quartile,
65
27 of the coefficients are positive. 24 of the positive coefficients are statistically
significant, and one more is marginally significant.
We also find that the sizes of the coefficients are similar across quartiles. The average
coefficients are 0.026, 0.026, and 0.029 and 0.027 in the first, second, and third and
fourth quartile, respectively.
As a final test, we consider the possibility that by calculating the producers’ size at the
category level, we might be underestimating the size of producers’ that offer products in
two or more categories. We, therefore, pool the data from all the product categories
together.
Table H3 reports the results of regressions similar to the regressions we report in Table
6 in the paper. I.e.:
(H2)
where small price change is a dummy that equals 1 if a price change of product i in store
s at time t is less or equal to 10¢, and 0 otherwise. The average sales volume is the
average sales volume of product i in store s over the sample period. X is a matrix of other
control variables. Month, year and category are fixed effects for the month of the price
change, the year of the price change, and the product category.
and
are fixed
effects for stores and products, respectively, and u is an i.i.d error term.
In column 1, the other extra control variables include the average weekly number of
products per producer. The coefficient of the average sales volume is positive and
statistically significant ( ). It, therefore, seems that controlling for the
size of the producers does not change our main finding: there is a positive correlation
between the sales volume and the likelihood of a small price change.
In column 2, we also add a control for the percentage of the products that changed the
price in the same week, excluding the current observation. This does not affect the
coefficient of the average sales volume.
In column 3, we further add the average size of contemporaneous price changes,
excluding the current observation. The coefficient of the average sales volume remains
unaffected. In column 4, we add the percentage of the products that are produced by the
66
same producer and that changed price in the same week, excluding the current
observation. The coefficient of the average sales volume remains unaffected (
).
67
Table H1. Percentage of small price changes by quartiles
1st Quartile
2nd Quartile
3rd Quartile
4th Quartile
Analgesics
15.04%
12.31%
12.19%
11.69%
Bath Soaps
18.46%
9.98%
12.38%
16.81%
Bathroom Tissues
46.13%
33.03%
38.34%
50.17%
Beers
2.47%
3.95%
6.76%
8.48%
Bottled Juices
45.52%
36.06%
38.22%
29.14%
Canned Soups
58.63%
49.65%
48.05%
49.13%
Canned Tuna
61.09%
54.31%
55.64%
55.38%
Cereals
34.68%
28.89%
28.57%
32.99%
Cheese
64.29%
43.16%
33.49%
38.81%
Cigarettes
34.13%
29.13%
28.24%
25.09%
Cookies
27.28%
29.72%
23.85%
29.66%
Crackers
38.88%
48.10%
27.38%
23.88%
Dish Detergents
44.63%
41.61%
31.13%
31.20%
Fabric Softener
48.32%
28.68%
27.49%
28.86%
Front-End-Candies
59.34%
47.39%
43.92%
54.14%
Frozen Dinners
13.01%
23.86%
34.66%
20.28%
Frozen Entrees
20.46%
15.53%
15.19%
16.91%
Frozen Juices
30.44%
38.18%
42.51%
31.82%
Grooming Products
11.00%
10.97%
13.81%
14.41%
Laundry Detergents
27.60%
16.21%
16.62%
16.72%
Oatmeal
37.71%
46.51%
38.05%
40.84%
Paper Towels
55.84%
52.25%
52.61%
57.54%
Refrigerated Juices
32.12%
35.66%
32.95%
28.85%
Shampoos
7.41%
6.26%
7.82%
9.34%
Snack Cracker
38.75%
27.07%
20.87%
23.34%
Soaps
46.30%
49.18%
46.42%
38.02%
Soft Drinks
16.23%
13.71%
26.57%
9.06%
Toothbrushes
13.32%
8.16%
11.10%
12.68%
Toothpastes
14.64%
15.28%
15.86%
22.33%
Average
33.23%
29.48%
28.64%
28.54%
Notes: The table presents the % of small price changes in each quartile of producers’ size by category. To calculate the quartiles
of producers’ size, we first calculate the size of each producer in each category by finding the number of products sold by each
producer in each week and then averaging over all weeks. We then divide producers into quartiles using the average number
of products they sell each week.
68
Table H2. Category-level regressions of small price changes, by quartiles of
manufacturers’ size
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0298***
(0.0091)
0.013**
(0.0055)
0.0235***
(0.0065)
0.0338***
(0.0061)
Observations
34,663
37,456
35,731
36,611
Bath Soap
Coefficient
(Std.)
0.0359***
(0.0134)
0.0336**
(0.0163)
0.0218*
(0.0114)
0.0479**
(0.0233)
Observations
3,791
3,918
3,839
3,747
Bathroom
Tissues
Coefficient
(Std.)
0.0354***
(0.0099)
0.0904***
(0.0127)
0.0709***
(0.0165)
0.0306***
(0.0113)
Observations
39,311
36,016
37,423
36,691
Beer
Coefficient
(Std.)
0.0075***
(0.0017)
0.01***
(0.0015)
0.0153***
(0.0029)
0.0209***
(0.0031)
Observations
73,377
73,587
71,340
72,316
Bottled Juice
Coefficient
(Std.)
0.0126
(0.0088)
0.0303***
(0.0096)
0.0657***
(0.0092)
0.0313***
(0.008)
Observations
130,866
123,821
118,687
123,183
Canned Soup
Coefficient
(Std.)
0.0514***
(0.0087)
-0.0034
(0.0068)
0.0368***
(0.0065)
0.0204***
(0.0062)
Observations
121,911
131,751
120,162
121,719
Canned Tuna
Coefficient
(Std.)
0.0378***
(0.0081)
0.0071
(0.0081)
0.0241***
(0.0067)
0.0312***
(0.0093)
Observations
55,961
58,140
50,991
47,951
Cereals
Coefficient
(Std.)
0.0202***
(0.0073)
0.0229***
(0.0063)
0.0302***
(0.0064)
0.0202***
(0.0062)
Observations
94,391
85,049
87,359
90,321
Cheese
Coefficient
(Std.)
0.0264***
(0.0047)
0.0054
(0.0059)
0.0229***
(0.0041)
0.0283***
(0.005)
Observations
151,338
221,454
202,915
220,443
Cigarettes
Coefficient
(Std.)
-0.0025
(0.01)
0.0158**
(0.0064)
0.0218***
(0.0063)
-0.0065
(0.0075)
Observations
8,454
9,371
9,048
9,284
Cookies
Coefficient
(Std.)
0.0193***
(0.0023)
0.0383***
(0.0042)
0.0264***
(0.0035)
0.0283***
(0.0043)
Observations
189,332
160,793
168,919
169,717
Crackers
Coefficient
(Std.)
0.0375***
(0.0048)
0.0325***
(0.0042)
0.0345***
(0.0055)
0.0538***
(0.0095)
Observations
66,641
69,958
54,179
54,407
Dish
Detergent
Coefficient
(Std.)
0.0275***
(0.0093)
0.0455***
(0.0067)
0.0394***
(0.007)
0.0426***
(0.0059)
Observations
50,346
48,380
46,539
44,368
Fabric
Softener
Coefficient
(Std.)
0.0326***
(0.012)
0.0375***
(0.0073)
0.029***
(0.0077)
0.0333***
(0.0096)
Observations
51,749
42,994
44,935
41,378
Front-End-
Candies
Coefficient
(Std.)
0.0058
(0.0054)
0.0059
(0.0083)
0.0019
(0.0097)
-0.0165***
(0.0052)
Observations
70,136
64,179
66,019
78,519
Frozen
Dinners
Coefficient
(Std.)
0.0443***
(0.0064)
0.0472***
(0.0083)
0.049***
(0.0079)
0.0294***
(0.0071)
Observations
49,266
50,902
50,539
52,484
69
Table H2. (Cont.)
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 10¢. The main independent variable is the log of the average sales volume of product i in store s over the
sample period. The regressions also include fixed effects for months, years, stores, and products. Columns 1, 2, 3, and
4 are for the 1st, 2nd, 3rd, and 4th quartiles of the manufacturers’ size, measured using the average number of products
they sell each week. We estimate separate regressions for each product category, clustering the errors by product. * p <
10%, ** p < 5%, *** p < 1%
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0271***
(0.0033)
0.0321***
(0.0041)
0.0178***
(0.0038)
0.0191***
(0.0042)
Observations
231,065
205,922
218,170
209,675
Frozen Juices
Coefficient
(Std.)
0.0168
(0.0116)
0.0268***
(0.0065)
0.0245***
(0.0071)
0.0449***
(0.0072)
Observations
77,812
73,824
80,038
77,143
Grooming
Products
Coefficient
(Std.)
0.0143***
(0.0037)
0.0225***
(0.0038)
0.0213***
(0.0045)
0.0153***
(0.0048)
Observations
66,700
65,306
66,455
71,412
Laundry
Detergents
Coefficient
(Std.)
0.0216***
(0.0065)
0.0205***
(0.0069)
0.0297***
(0.0061)
0.0096
(0.006)
Observations
76,565
67,392
65,836
62,972
Oatmeal
Coefficient
(Std.)
0.0437**
(0.0207)
0.001
(0.0129)
0.0338***
(0.0146)
0.0171
(0.0113)
Observations
20,184
21,624
19,863
18,312
Paper Towels
Coefficient
(Std.)
0.0323**
(0.0145)
0.0333**
(0.0153)
0.0557**
(0.0245)
0.0761***
(0.0178)
Observations
26,835
31,117
29,325
28,927
Refrigerated
Juices
Coefficient
(Std.)
0.0289***
(0.0094)
0.0312***
(0.0071)
0.0256***
(0.008)
0.0358***
(0.0092)
Observations
81,959
73,635
76,575
74,696
Shampoos
Coefficient
(Std.)
0.0208***
(0.0032)
0.0095***
(0.0023)
0.0082***
(0.003)
0.0229***
(0.003)
Observations
64,883
63,777
66,146
66,972
Snack
Crackers
Coefficient
(Std.)
0.0375***
(0.0063)
0.0403***
(0.0066)
0.0187***
(0.0049)
0.0264***
(0.005)
Observations
100,802
108,690
97,783
91,390
Soaps
Coefficient
(Std.)
0.0456***
(0.0078)
0.0437***
(0.0102)
0.0277**
(0.0118)
0.0324***
(0.0115)
Observations
39,742
39,140
38,084
35,413
Soft Drinks
Coefficient
(Std.)
0.0211***
(0.0022)
0.0274***
(0.0026)
0.0257***
(0.0036)
0.0253***
(0.0032)
Observations
346,043
355,732
350,552
298,291
Toothbrushes
Coefficient
(Std.)
0.0211***
(0.0043)
0.0146***
(0.0052)
0.0256***
(0.0058)
0.0176***
(0.0075)
Observations
33,948
27,258
32,415
31,759
Toothpastes
Coefficient
(Std.)
0.0149***
(0.0052)
0.0198***
(0.0045)
0.0127***
(0.0048)
0.0089
(0.0063)
Observations
64,984
63,457
68,506
67,370
Average coefficients
0.0265
0.0260
0.0290
0.0269
70
Table H3. Pooled data regressions of small price changes and synchronization
(1)
(2)
(3)
(4)
Log of sales volume
0.027***
(0.001)
0.027***
(0.001)
0.027***
(0.001)
0.027***
(0.001)
Observations
9,553,542
9,553,542
9,553,536
9,392,565
Notes: The table reports the results of pooled fixed effect regressions of the probability of a small price change. The
dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less or equal
to 10¢, and 0 otherwise. The main independent variable is the log of the average sales volume product i in store s over the
sample period. Column 1 reports the results of the baseline regression that includes only the log of the average sales volume
and the fixed effects for months, years, categories, stores, and products. In column 2, we add the average number of
products each producer offers each week. In column 3, we add the percentage of the products that changed the price on the
same week, excluding the current observation as an additional control. In column 4, we control synchronization by adding
the percentage of the products that have been produced by the same producer and that changed price in the same week,
excluding the current observation. We estimate a pooled regression, clustering the errors by product. * p < 10%, ** p <
5%, *** p < 1%
71
Appendix I. Results of cross-category analysis
Table I1 shows the number of all price changes and the number of small price
changes
( ¢0 )1P
by product category, the percentage of small price changes out of all
price changes, and the average sales volume. The latter is calculated by first finding the
average weekly sales volume for each product in each store (product-store) in the
category, and then averaging over all products.
4
There is a large cross-category variation in the share of small price changes, ranging
from 3.3% in the beer category to 55.2% in the paper towels category. This variation is
accompanied by a large variation in the average sales volume. As shown in Figure I2 and
table I4, the variation in the category-level average sales volume is mostly driven by the
number of choices available to consumers. At the category level, a 1% increase in the
number of products is associated with a 0.84% decrease in the expected average sales
volumes.
More importantly, however, there is a strong correlation between the average sales
volume and the share of small price changes. Figure I1 shows a scatterplot of the
category-level average sales volume and the percentage of small price changes, along
with a linear regression line (solid line). We find a positive correlation between the two
variables. The correlation is even stronger (dashed line) if we exclude paper towels and
bathroom tissues, two categories with particularly high values of both average sales
volume and percentage of small price changes.
To explore this correlation formally, we run cross-category OLS regressions, where
the dependent variable is the category-level percentage of small price changes. See Table
I2. In column 1, the independent variable is the average weekly sales volume. The
coefficient estimate of 0.95 implies that a one-unit increase in the average weekly sales
volume is associated with a 0.95% increase in the percentage of small price changes.
A possible explanation for this correlation could be that categories with low average
4
In calculating the average sales volume, we need to account for missing observations, because a missing observation
in week t implies that the product was either out of stock or had 0 sales on that week. Thus, averaging over the
available observations can lead to an upward bias for products that are sold in small numbers. Therefore, for each
product in each store, we calculate the average by first determining the total number of units sold over all available
observations. We then identify the first and last week for which we have observations, and calculate the average for
each product-store as
. The resulting figure is smaller than we would obtain if we averaged over all
available observations (which would not include observations on weeks with 0 sales).
72
price levels have higher shares of small price changes and higher sales volume. The
regression in column 2 shows that there is indeed a negative correlation between the
average price in a category and the percentage of small price changes. However, in
column 3, which reports the results of a regression that includes both the average prices
and the average sales volume as independent variables, we find that the coefficient of the
average sales volume is 0.78 and statistically significant. Thus, we find that sales volume
is correlated with small price changes even after controlling for the price level.
An alternative explanation could be competition. It could be that products in high
sales volume categories face stronger competition, and their producers may want to avoid
large price changes that could alienate consumers. On the other hand, it is also possible
that competition would have a negative effect on the prevalence of small price changes.
Wang and Werning (2022) argue that concentrated markets increase the likelihood of
pricing complementarities. This suggests that small price changes might be more likely in
markets where producers have greater market power.
In column 4, we look at the correlation between the percentage of small price changes
and category-level estimates of own price elasticities which are taken from Hoch et al.
(1995). We find that the correlation is negative, but not statistically significant. In column
5, where we report the results of a regression with both the sales volume and the price
elasticity as independent variables, we find that the coefficient of the sales volume is
0.80, and statistically significant.
The coefficient of the elasticity is negative and statistically significant. I.e., small
price changes are more common in product categories with low rather than high price
elasticities (in absolute values), which is consistent with pricing complementarities.
However, our results suggest that even after accounting for pricing complementarities,
the effect of the sales volumes is positive and statistically significant.
As discussed above, table I1 shows that there is a large variation in the average sales
volume across categories. In particular, the average weekly sales volume per store in the
categories of bathroom tissues and paper towels, 40.35 and 38.92, respectively, stand out:
they both are much larger than the average sales volumes in other categories. In contrast,
the weekly average sales volume per store in the categories of bath soaps and shampoos,
0.72 and 0.84, are much smaller than the average in other categories.
73
To a large extent, these variations in the sales volume can be explained by product
variety, which can be measured by looking at the number of Universal Product Codes
(UPCs) in each category, which captures the number of options consumers can choose
from. Table I3 gives the average sales volumes and the number of UPCs for each
category.
5
Figure I2 illustrates that the average sales volume is negatively correlated with
the number of UPCs. For example, the product categories with the highest sales volumes,
bathroom tissues and paper towels, have a relatively small number of UPCs, 102 and 91,
respectively. For comparison, the product categories with the lowest average sales
volumes, bath soaps and shampoos, have 495 and 1,905 UPCs, respectively.
The negative correlation between the average sales volume and the number of UPCs
is statistically significant. Table I4 reports the results of a category level linear regression
of the log of the average sales volume on the log of the number of UPCs. According to
the table, the correlation is statistically significant ( ). Thus, a 1%
increase in the number of UPCs per category is associated with a decrease of 0.84% in
the average weekly sales volume per store.
Thus, the large variation in the sales volume should not be surprising. In categories
with many UPCs, it appears that a large number of UPCs sell a small number of units,
leading to a low average weekly sales volume per store.
5
It turns out the Dominick’s occasionally used different UPCs for the same products, perhaps because a product was
re-launched (Mehrhoff, 2018). Whenever possible, we treat re-launches as the same product and, consequently, the
number of products that we report might differ from the number reported in previous studies, e.g., Chen et al. (2008).
See also the Dominick’s data manual (https://www.chicagobooth.edu/-
/media/enterprise/centers/kilts/datasets/dominicks-dataset/dominicks-manual-and-codebook_kiltscenter.aspx), p. 9.
74
Table I1. The proportion of small price changes and the average sales volume by product categories
Product
Category
All price
changes
(1)
Small price
changes
(2)
% of small
price changes
(3)
Average sales
volume
(4)
Analgesics
144,461
16,608
11.5%
1.24
Bath soap
15,295
1,783
11.7%
0.72
Bathroom tissues
149,441
60,263
40.3%
40.35
Beer
290,620
9,526
3.3%
3.58
Bottled juices
496,557
170,762
34.4%
8.27
Canned soups
495,543
281,649
56.8%
12.25
Canned tuna
213,043
111,473
52.3%
9.34
Cereals
357,120
112,298
31.4%
15.02
Cheese
796,150
309,021
38.8%
11.32
Cigarettes
36,157
10,527
29.1%
21.20
Cookies
688,761
161,826
23.5%
4.96
Crackers
245,185
77,658
31.7%
4.89
Dish detergents
189,633
67,109
35.4%
7.38
Fabric softeners
181,056
55,199
30.5%
5.56
Front end candies
278,853
124,432
44.6%
10.70
Frozen dinners
203,191
45,050
22.2%
5.64
Frozen entrees
864,832
127,039
14.7%
6.32
Frozen juices
308,817
106,398
34.5%
16.82
Grooming products
269,873
24,172
9.0%
1.21
Laundry detergents
272,765
51,739
19.0%
6.59
Oatmeal
79,983
34,271
42.8%
7.32
Paper towels
116,204
64,183
55.2%
38.92
Refrigerated juices
306,865
91,124
29.7%
19.80
Shampoos
261,778
14,228
5.4%
0.84
Snack crackers
398,665
93,754
23.5%
6.79
Soaps
152,379
60,635
39.8%
5.02
Soft drinks
1,350,618
206,373
15.3%
13.05
Toothbrushes
125,380
13,306
10.6%
2.09
Toothpastes
264,317
38,894
14.7%
3.31
Total
9,553,542
2,541,300
26.6%
10.02
Notes: Column 1 presents the total number of price changes in each category. Column 2 presents the number of small
price changes
( ¢0 )1P
. Column 3 presents the % of small price changes out of all price changes. Column 4
presents the average number of units sold per product, per week, per store. The average number of units sold is
calculated taking into account that missing observations often imply 0 sales.
75
Table I2. Cross-category regression of the % of small price changes and sales volume
(1)
(2)
(3)
(4)
(5)
Average
sales
volume
0.95***
(0.262)
0.78**
(0.270)
0.80***
(0.268)
Average
price
4.59**
(1.703)
2.88*
(1.621)
Absolute
elasticity
7.78
(6.208)
11.53**
(5.223)
Constant
19.29***
(3.319)
45.65***
(5.327)
28.85***
(6.249)
44.93***
(10.504)
40.97***
(8.681)
2
R
0.33
0.21
0.40
0.09
0.43
Number of
categories
29
29
29
18
18
Notes: The table presents the results of OLS regressions. The dependent variable is the % of small price changes out of all price
changes, in each of the 29 categories. Small price changes are defined as price changes of
10¢P
. The average price is the average
price in the product category. The absolute elasticity is the absolute value of the demand price elasticity estimates as reported by
Hoch et al. (1995). Columns (4) and (5) contain only 18 observations because Hoch et al. (1995) provide elasticity estimates only
for 18 of the 29 product categories. * p < 10%, ** p < 5%, *** p < 1%
76
Table I3. Category-level average sales volume and the number of UPCs
Product
Category
Average sales volume
(1)
Number of UPCs
(2)
Analgesics
1.24
507
Bath soap
0.72
495
Bathroom tissues
40.35
102
Beer
3.58
653
Bottled juices
8.27
445
Canned soups
12.25
413
Canned tuna
9.34
212
Cereals
15.02
399
Cheese
11.32
573
Cigarettes
21.20
78
Cookies
4.96
976
Crackers
4.89
295
Dish detergents
7.38
183
Fabric softeners
5.56
203
Front end candies
10.70
416
Frozen dinners
5.64
254
Frozen entrees
6.32
822
Frozen juices
16.82
161
Grooming products
1.21
962
Laundry detergents
6.59
353
Oatmeal
7.32
93
Paper towels
38.92
91
Refrigerated juices
19.80
227
Shampoos
0.84
1,905
Snack crackers
6.79
382
Soaps
5.02
1,370
Soft drinks
13.05
243
Toothbrushes
2.09
325
Toothpastes
3.31
376
Average
10.02
466.00
Notes: Column 1 presents the average number of units sold per product, per week, per store. Column 2 presents the
number of UPCs in each product category.
77
Table I4. Average sales volume and the number of UPCs
ln (average sales volume)
ln (Number of UPCs)
−0.84***
(0.186)
Constant
6.77***
(1.098)
0.35
Observations
29
Notes: The table reports the results of a category-level linear regression with robust standard errors. The
dependent variable is the log of the average weekly sales volume per store. The independent variable is the
log of the number of UPCs in each category. Standard errors are in parentheses. *** p < 0.01.
78
Figure I1. Cross-category correlation between small price changes and sales
volume
Notes: The red solid line is a linear regression line when all 29 product categories are included. The dotted
green line is the linear regression line when two categories, paper towels and bathroom tissues, are excluded.
79
Figure I2. Average sales volume and the number of UPCs
Notes: The y-axis gives the average weekly sales volume per store in each of the 29 categories. The x-
axis gives the number of UPCs per category. The red line gives the prediction line based on a log-log
regression specification.
80
Appendix J. Sales volume, markup, and small price changes
Our results suggest that small price changes should be relatively common for products
with high sales volumes. Yet, in the marketplace there are products with high sales
volumes that rarely have small price changes. One example is the iPhone.
A possible explanation is that the likelihood of small price changes is negatively
correlated with markups. It is possible that sellers that have high markups are less likely
to make small price changes, because the effect of a small price change on the profits of a
firm with high markup could be small in percentage terms.
To check this, we take advantage of the fact that Dominick’s data contain a proxy for
the products’ markup (Barsky et al., 2003), and thus estimate a regression that is similar
to regression (1) in the paper:
(J1)
where small price change is a dummy that equals 1 if a price change of product i in store
s at time t is less than or equal to 10¢, and 0 otherwise. As we do in the paper, we use
observations on price changes only if we observe the price in both weeks t and t + 1 and
the post change price remained unchanged for at least 2 weeks. The average sales volume
is the average sales volume of product i in store s over the sample period. The average
markup is the average markup of product i in store s over the sample period. Month and
year are fixed effects for the month and the year of the price change.
and
are fixed
effects for stores and products, respectively, and u is an i.i.d error term.
The results are summarized in Table J1. Panel A gives information about the
coefficients of the sales volumes in each of the 29 product categories. We find that all 29
coefficients are positive. 15 of the coefficients are statistically significant, and 1 more is
marginally significant. Panel B gives information about the coefficients of the markup.
We find that consistent with the hypothesis that a high markup is associated with a lower
frequency of small price changes, the coefficients of the markup are negative in 21 of the
29 product categories, 13 of them statistically significant.
The results, therefore, suggest that there is, indeed, a negative correlation between
markups and the frequency of small price changes. Adding the markups to the regression,
81
however, does not affect our main finding. There is a positive correlation between sales
volumes and small price changes.
82
Table J1. Sales volume, markup, and small price changes
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change. The
dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less or equal
to 10¢. The main independent variables are the log of the average sales volume of product i in store s over the sample
period, and the average markup of product i in store s over the sample period. The regressions also include fixed effects for
months, years, stores, and products. The LHS panel reports the coefficient of the average sales volume. The RHS panel
reports the coefficient of the average markups. We estimate separate regressions for each product category, clustering the
errors by product. * p < 10%, ** p < 5%, *** p < 1%
Category
Sales Volume
Markup
No. of
Observations
Coefficient
Std.
Coefficient
Std.
Analgesics
0.0163***
0.0040
-0.1157***
0.0371
74,451
Bath Soap
0.01
0.0129
0.1211
0.1138
6,649
Bathroom Tissues
0.0392***
0.0086
-0.2302***
0.0373
56,445
Beer
0.0021***
0.0007
0.0001
0.0011
178,518
Bottled Juice
0.0314***
0.0075
-0.2746***
0.0568
224,857
Canned Soup
0.0017
0.0090
0.0011
0.0692
233,778
Canned Tuna
0.0032
0.0061
-0.3597***
0.0694
112,628
Cereals
0.0048
0.0065
-0.0681
0.0497
141,082
Cheese
0.0109***
0.0036
-0.6253***
0.0790
357,679
Cigarettes
0.0037
0.0050
0.1909***
0.0358
24,553
Cookies
0.0086***
0.0019
-0.0247
0.0376
317,932
Crackers
0.0012
0.0033
-0.1905***
0.0575
115,657
Dish Detergent
0.028***
0.0064
-0.4664***
0.1218
85,222
Fabric Softener
0.0085
0.0065
-0.4819***
0.1307
85,337
Front-End-Candies
0.0098**
0.0041
-0.1295
0.0908
148,200
Frozen Dinners
0.0517***
0.0069
-0.1548
0.1058
52,893
Frozen Entrees
0.0227***
0.0026
-0.19***
0.0476
345,223
Frozen Juices
0.0181**
0.0071
-0.3513***
0.1189
118,582
Grooming Products
0.0095***
0.0033
0.0302
0.0290
101,918
Laundry Detergents
0.0189***
0.0045
-0.1422***
0.0328
121,539
Oatmeal
0.016
0.0123
0.0513
0.0870
25,513
Paper Towels
0.0113
0.0141
-0.7104***
0.1077
48,198
Refrigerated Juices
0.0129*
0.0077
-0.052
0.0665
108,964
Shampoos
0.01***
0.0025
-0.0067
0.0121
88,163
Snack Crackers
0.0023
0.0029
-0.0868
0.0654
176,527
Soap
0.0258***
0.0088
-0.1312
0.0943
56,725
Soft Drinks
0.0306***
0.0045
0.0029
0.0026
230,185
Toothbrushes
0.0137***
0.0046
-0.1526***
0.0578
52,181
Toothpastes
0.0015
0.0039
0.0412
0.0296
100,831
Average
0.0146
0.0059
0.1554-
0.0636
746,413
83
Appendix K. Category level correlation between sales volumes and the size of price
changes
Figure 2 in the paper uses deciles plot to illustrate the correlation between sales
volumes and the size of small price changes when we pool data from all categories.
Figure K1 illustrates the correlation between sales volumes and the size of small price
changes at the category level. The figure depicts, for each category, the scatter plots of
the size of price changes, in cents, on the x-axis, vs. the average sales volume, on the y-
axis. The average sales volume is calculated at the store-product level, i.e., for individual
goods at each store.
The figure shows that the relationship tends to have a pyramid shape – broad at the
bottom, suggesting that relatively large price changes occur at all levels of sales volumes.
Small price changes, however, are more likely to occur when the sales volume is high,
yielding the pyramid shape.
84
Figure K1. Sales volume and small price changes
85
Figure K1. (cont.)
Notes: The figure depicts, for each of the 29 product categories, the correlation between the size of price
changes (x-axis) and the average sales volume (y-axis). The average sales volume is calculated separately
for each product in each store.
86
Appendix L. Frequency of price changes by size for high, medium, and low sales
volume products – in percentage terms
In the paper, we present Figure 3, which shows that within product categories, price
changes in general, and small price changes in particular, are more common among high
sales volume products than among middle and low sales volume products. In Figure 3,
we measure the size of price changes in cents. However, this has the disadvantage that
some price changes that are multiples of 10 cents are much more frequent than other
price changes.
In addition, when we measure the size of price changes by cents, we might identify a
price change as small because its size is less than 10 cents. In percentage terms, however,
this price change might be large. E.g., if a good costs less than 1 dollar.
We therefore generate a figure similar to figure 3, but this time we measure the size
of price changes in percentage terms. To draw the figure, we first compute for each
product in each store, the average sales volume over the entire sample period. By taking
the average over a long period, we obtain an estimate of the expected sales volume that
does not depend on transitory shocks or sales. We then group the products into high,
medium and low sales volume products. Low sales volume products are products with
average sales volume in the lower third of the distribution, high sales volume products
have sales volume in the higher third of the distribution, and medium sales volume
products have sales volume in between.
Figure L1 shows, for every product category, the frequency of price changes for each
size of price change from 1% to 30%. As we do in the paper, we use observations on
price changes only if we observe the price in both weeks t and t + 1 and the post change
price remained unchanged for at least 2 weeks.
The red dashed line depicts the frequency of price changes among high sales volume
products, the green dotted line depicts the frequency of price changes among middle sales
volume products, while the blue solid line depicts the frequency of price changes among
low sales volume products. The shaded area marks the range of small price changes,
.
We find that in comparison to Figure 3 in the paper, the lines on Figure L1 are
smoother, without the peaks at multiples of 10 cents. However, in some categories, there
87
are small peaks, particularly at 20% and 25%, perhaps because sale prices and discounts
are often set in percentage terms.
We also find that similar to Figure 3 in the paper, price changes are more common
among high sales volume products, and least common among low sales volume products.
Focusing on the shaded area, we see that the frequency of small price changes is far
greater among the high sales-volume products than among low sales volume products.
Indeed, for high sales volume products, in most product categories, the frequency of
small price changes exceeds the frequency of large price changes. This is far less
common, and less dramatic, among low sales volume products. For the middle sales
volume products, the frequency of price changes, and the frequency of small price
changes in particular, is in general in between the frequencies of the low and high sales
volume products.
88
Figure L1. Frequency of price changes by size, in % terms, for high, middle, and
low sales volume products
89
Figure L1 (cont.).
Notes: For each category, the figure shows the frequency of price changes for each size of price change from 1%
to 30%, comparing high sales volume products to medium and low sales volume products. To obtain the figures,
we compute the average sales volume over the entire sample period for each product, in each store. We then group
the products into high, medium, and low sales volume products. High (low) sales volume products are products in
the high (low) third of the distribution. Medium sales volume products fall in between. The y-axis shows the
frequency of price changes. The red dashed line depicts the frequency of price changes for the high sales-volume
products, the green dotted line depicts the frequency of price changes for the medium sales-volume products, and
the blue solid line depicts the frequency of price changes for the low sales volume products. The shaded area marks
the range of small price changes, .
90
Appendix M. National brand vs. private label products
It is possible that the correlation between small price changes and sales volumes is
an artifact of differences in the patterns of demand between products. In this appendix,
therefore, we separate private label and national brand products and analyze them
separately, because they tend to have different price levels and different patterns of
demand. If our results are an artifact of the pattern of demands, then it is possible that
sales volumes would have a different effect on private label products than on national
brands.
In the first analysis, we use all price changes, conditional on observing the price one-
week before the price change. We then re-estimate the model, using only observations on
price changes if the post-change price remained unchanged for at least two weeks. The
second analysis is consistent with our analysis in the paper and in the other appendices.
However, it has the disadvantage of having too few observations on private label
products’ price changes, leading to imprecise estimates.
Focusing first on all price changes, Table M1 (M2) presents the results of
regressions equivalent to the regressions in Table 3 in the paper. This time, however, we
focus on national brand (private label) products. The regressions take the following form:
, , , , ,
,,
ln( )
i s t i s i s t
t t s i i s t
small price change average sales volume
month year u
X
(M1)
where small price change is a dummy that equals 1 if a price change of product i in store
s at time t is less or equal to 10¢, and 0 otherwise. The average sales volume is the
average sales volume of product i in store s over the sample period. X is a matrix of other
control variables. Month and year are fixed effects for the month and the year of the price
change.
and
are fixed effects for stores and products, respectively, and u is an i.i.d
error term. We estimate separate regressions for each product category, clustering the
errors by product.
The values in Table M1 are the coefficients of the log of the average sales volume
when we focus on the sample of national brand products. In column 1, the only control
variables are the log of the average sales volume, and dummies for months, years, stores,
and products. Consistent with the results we report in the paper, we find that all the
91
coefficients of the log of the average sales volume are positive. 29 of the 29 coefficients
are positive, and 28 of them are statistically significant. The only exception is the
coefficient of the highly regulated cigarettes category. The average coefficient is 0.036,
suggesting that a 1% increase in the sales volume is associated with a 3.6% increase in
the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). All the coefficients are
positive and statistically significant: 27 at the 1% level, and two at the 10% level. The
average coefficient is 0.029, suggesting that a 1% increase in the sales volume is
associated with a 2.9% increase in the likelihood of a small price change.
In column 3, we also add a control for 9-ending prices. All coefficients remain
positive and statistically significant: 27 at the 1% level, and two at the 10% level. The
average coefficient is 0.025, suggesting that a 1% increase in the sales volume is
associated with a 2.5% increase in the likelihood of a small price change.
As a further control, in column 4 we focus on regular prices by excluding all sale
and bounce-back prices. When we focus on regular prices, all the coefficients are positive
and 28 statistically significant at the 1% level. The average coefficient is 0.045,
suggesting that a 1% increase in the sales volume is associated with a 4.5% increase in
the likelihood of a small price change.
The values in Table M2 are the coefficients of the log of the average sales volume
when we use the sample of private label products. When we focus on private labels, we
are left with 24 product categories, because in five categories, which include beers,
cigarettes, front-end-candies, frozen dinners and soaps, we have less than 500
observations on private labels.
In column 1, the only control variables are the log of the average sales volume, and
dummies for months, years, stores, and products. Consistent with the results we report in
the paper, we find that 23 of the 24 estimated coefficients of the log of the average sales
volume are positive. 19 of the positive coefficients are statistically significant, and one
more is marginally statistically significant. The one negative coefficient (toothbrushes
category) is not statistically significant. The average coefficient is 0.039, suggesting that
92
a 1% increase in the sales volume is associated with a 3.9% increase in the likelihood of a
small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). 23 of the 24 coefficients
are positive. 15 of the positive coefficients are statistically significant, and one more is
marginally statistically significant. The one negative coefficient (toothbrushes category)
is not statistically significant. The average coefficient is 0.030, suggesting that a 1%
increase in the sales volume is associated with a 3.0% increase in the likelihood of a
small price change.
In column 3, we also add a control for 9-ending prices. Again, 23 of the 24
coefficients are positive. 13 of the positive coefficients are statistically significant, and
one more is marginally statistically significant. The one negative coefficient
(toothbrushes) is not statistically significant. The average coefficient is 0.024, suggesting
that a 1% increase in the sales volume is associated with a 2.4% increase in the likelihood
of a small price change.
As a further control for a possible effect of sales on the results, in column 4 we focus
on regular prices by excluding all sale- and bounce-back prices. When we focus on
regular prices, all the coefficients are positive. 14 of the positive coefficients are
statistically significant, and 5 more are marginally statistically significant. The average
coefficient is 0.047, suggesting that a 1% increase in the sales volume is associated with a
4.7% increase in the likelihood of a small price change.
We, therefore, find that sales volumes are positively correlated with the likelihood of
small price changes among private label products as well as among national brand
products.
Focusing on price changes only if the post-change price survived for at least two
weeks, Table M3 (M4) presents the results of regressions equivalent to the regressions in
Table 3 in the paper. This time, however, we focus on national brand (private label)
products.
In column 1 of Table M3, the control variables are the log of the average sales
volume, and dummies for months, years, stores, and products. We find that all 29
93
coefficients of the log of the average sales volume are positive. 17 of the positive
coefficients are statistically significant, and 4 more are marginally significant. The
average coefficient is 0.016, suggesting that a 1% increase in the sales volume is
associated with a 1.6% increase in the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). 26 of the coefficients are
positive. 18 of them are statistically significant, and one more is significant at the 10%
level. The average coefficient is 0.009, suggesting that a 1% increase in the sales volume
is associated with a 0.9% increase in the likelihood of a small price change.
In column 3, we add a control for 9-ending prices. 26 of the coefficients are positive.
13 of them are statistically significant, and 3 more are significant at the 10% level. The
average coefficient is 0.009, suggesting that a 1% increase in the sales volume is
associated with a 0.9% increase in the likelihood of a small price change.
As a further control, in column 4 we focus on regular prices by excluding all sale
and bounce-back prices. 28 of the coefficients are positive. 16 of them are statistically
significant, and 3 more are significant at the 10% level. The average coefficient is 0.020,
suggesting that a 1% increase in the sales volume is associated with a 2.0% increase in
the likelihood of a small price change.
The values in Table M4 are the coefficients of the log of the average sales volume
when we use the sample of private-label products. When we focus on private labels, the
estimation is imprecise because in many categories we only have a small number of
observations. Consequently, we are left with 23 product categories, because in 6
categories, which include bath-soaps, beers, cigarettes, front-end-candies, frozen dinners
and soaps, we have less than 500 observations on price changes.
In column 1, the control variables are the log of the average sales volume, and
dummies for months, years, stores, and products. We find that 15 of the 23 estimated
coefficients of the log of the average sales volume are positive. 5 of the positive
coefficients are statistically significant, and 3 more are marginally statistically significant.
One of the negative coefficients (cereals) is statistically significant. The average
coefficient is 0.013, suggesting that a 1% increase in the sales volume is associated with a
94
1.3% decrease in the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). 12 of the 23 coefficients
are positive. 3 of the positive coefficients are statistically significant, and 4 more are
marginally statistically significant. 2 of the negative coefficients (cereals and refrigerated
juices) are statistically significant. The average coefficient is 0.007, suggesting that a 1%
increase in the sales volume is associated with a 0.7% decrease in the likelihood of a
small price change.
In column 3, we add a control for 9-ending prices. 12 of the 23 coefficients are
positive. 4 of the positive coefficients are statistically significant, and 1 more is
marginally statistically significant. 2 of the negative coefficients (cereals and refrigerated
juices) are statistically significant. The average coefficient is 0.007, suggesting that a 1%
increase in the sales volume is associated with a 0.7% decrease in the likelihood of a
small price change.
As a further control for a possible effect of sales on the estimation results, in column
4 we focus on regular prices by excluding all sale- and bounce-back prices. 12 of the 23
coefficients are positive. 5 of the positive coefficients are statistically significant, and 1
more is marginally statistically significant. 2 of the negative coefficients (cereals and
refrigerated juices) are statistically significant. The average coefficient is 0.014,
suggesting that a 1% increase in the sales volume is associated with a 1.4% decrease in
the likelihood of a small price change.
95
Table M1. Category-level regressions of small price changes and sales volume, using
observations on national brand products
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0379***
(0.0038)
0.0305***
(0.0031)
0.0254***
(0.0029)
0.0481***
(0.0063)
Observations
242,823
242,823
242,823
64,271
Bath Soap
Coefficient
(Std.)
0.0455***
(0.0101)
0.0502***
(0.0102)
0.0471***
(0.0099)
0.0892***
(0.0167)
Observations
30,747
30,747
30,747
6,285
Bathroom
Tissues
Coefficient
(Std.)
0.0357***
(0.0057)
0.0178***
(0.0052)
0.0155***
(0.0049)
0.0335***
(0.0071)
Observations
305,784
305,784
305,784
75,080
Beer
Coefficient
(Std.)
0.023***
(0.0015)
0.0249***
(0.0012)
0.0208***
(0.0012)
0.0687***
(0.005)
Observations
457,795
457,795
457,795
56,283
Bottled Juice
Coefficient
(Std.)
0.0552***
(0.0049)
0.037***
(0.0034)
0.0326***
(0.0035)
0.0322***
(0.005)
Observations
838,222
838,222
838,222
212,093
Canned Soup
Coefficient
(Std.)
0.0265***
(0.0044)
0.0146***
(0.0037)
0.0154***
(0.0035)
0.021***
(0.0042)
Observations
890,105
890,105
890,105
260,495
Canned Tuna
Coefficient
(Std.)
0.0353***
(0.0052)
0.026***
(0.0044)
0.0221***
(0.0041)
0.0323***
(0.0048)
Observations
355,663
355,663
355,663
110,267
Cereals
Coefficient
(Std.)
0.0235***
(0.0028)
0.019***
(0.0023)
0.0184***
(0.0023)
0.0264***
(0.0038)
Observations
641,499
641,499
641,499
244,435
Cheese
Coefficient
(Std.)
0.0382***
(0.0032)
0.0215***
(0.0024)
0.0184***
(0.0024)
0.01***
(0.0032)
Observations
1,382,175
1,382,175
1,382,175
452,595
Cigarettes
Coefficient
(Std.)
0.0152
(0.0093)
0.0154
(0.0082)
0.0151*
(0.008)
0.0141
(0.0086)
Observations
6,982
6,982
6,982
4,120
Cookies
Coefficient
(Std.)
0.0419***
(0.0019)
0.0369***
(0.0018)
0.0317***
(0.0017)
0.0536***
(0.0032)
Observations
1,172,710
1,172,710
1,172,710
202,932
Crackers
Coefficient
(Std.)
0.0545***
(0.0036)
0.0432***
(0.0033)
0.0392***
(0.0031)
0.0545***
(0.0065)
Observations
440,282
440,282
440,282
83,083
Dish
Detergent
Coefficient
(Std.)
0.0507***
(0.0039)
0.0359***
(0.0031)
0.0312***
(0.0031)
0.0405***
(0.0047)
Observations
338,430
338,430
338,430
84,418
Fabric
Softener
Coefficient
(Std.)
0.0327***
(0.0039)
0.0215***
(0.0036)
0.0183***
(0.0037)
0.0383***
(0.0051)
Observations
318,661
318,661
318,661
88,496
Front-End-
Candies
Coefficient
(Std.)
0.0166***
(0.0039)
0.0092***
(0.0028)
0.0082***
(0.0027)
0.0114***
(0.0032)
Observations
485,323
485,323
485,323
153,759
Frozen
Dinners
Coefficient
(Std.)
0.0534***
(0.0027)
0.0405***
(0.0024)
0.0391***
(0.0024)
0.0902***
(0.0059)
Observations
502,329
502,329
502,329
72,589
96
Table M1. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0352***
(0.0019)
0.0298***
(0.0017)
0.029***
(0.0017)
0.0589***
(0.0032)
Observations
1,835,884
1,835,884
1,835,884
351,172
Frozen Juices
Coefficient
(Std.)
0.0329***
(0.0037)
0.0256***
(0.0032)
0.023***
(0.0031)
0.0295***
(0.0047)
Observations
540,070
540,070
540,070
128,103
Grooming
Products
Coefficient
(Std.)
0.0421***
(0.0024)
0.0451***
(0.0022)
0.0387***
(0.0022)
0.0651***
(0.0061)
Observations
639,004
639,004
639,004
94,837
Laundry
Detergents
Coefficient
(Std.)
0.0188***
(0.0029)
0.015***
(0.0025)
0.012***
(0.0023)
0.0238***
(0.0049)
Observations
544,928
544,928
544,928
137,209
Oatmeal
Coefficient
(Std.)
0.0284***
(0.0079)
0.0177***
(0.0057)
0.0155***
(0.0056)
0.0291***
(0.0093)
Observations
146,887
146,887
146,887
59,961
Paper Towels
Coefficient
(Std.)
0.0381***
(0.0125)
0.0264*
(0.0133)
0.0252*
(0.0136)
0.0292***
(0.0104)
Observations
216,280
216,280
216,280
47,035
Refrigerated
Juices
Coefficient
(Std.)
0.0312***
(0.0034)
0.0205***
(0.0028)
0.018***
(0.0027)
0.0291***
(0.0044)
Observations
716,448
716,448
716,448
147,024
Shampoos
Coefficient
(Std.)
0.0328***
(0.0014)
0.0373***
(0.0014)
0.0324***
(0.0013)
0.0675***
(0.0043)
Observations
701,525
701,525
701,525
85,168
Snack
Crackers
Coefficient
(Std.)
0.0431***
(0.0034)
0.0379***
(0.0031)
0.0338***
(0.0028)
0.0658***
(0.0042)
Observations
751,170
751,170
751,170
133,817
Soaps
Coefficient
(Std.)
0.057***
(0.0053)
0.0424***
(0.0045)
0.0347***
(0.0042)
0.0563***
(0.0058)
Observations
323,840
323,840
323,840
93,074
Soft Drinks
Coefficient
(Std.)
0.027***
(0.0012)
0.0255***
(0.0011)
0.0212***
(0.001)
0.0608***
(0.0029)
Observations
3,748,192
3,748,192
3,748,192
301,273
Toothbrushes
Coefficient
(Std.)
0.029***
(0.0032)
0.0322***
(0.0033)
0.0269***
(0.0031)
0.062***
(0.0064)
Observations
275,080
275,080
275,080
41,256
Toothpastes
Coefficient
(Std.)
0.0286***
(0.0032)
0.0277***
(0.0027)
0.0238***
(0.0026)
0.0581***
(0.0064)
Observations
570,338
570,338
570,338
86,903
Average coefficients
0.036
0.029
0.025
0.045
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price
change, using observations on national brand products. The dependent variable is “small price change,” which
equals 1 if a price change of product i in store s at time t is less or equal to 10¢, and 0 otherwise. The main
independent variable is the log of the average sales volume of product i in store s over the sample period.
Column 1 reports the results of baseline regression that includes only the log of the average sales volume and
the fixed effects for months, years, stores, and products. In column 2, we add the following controls: the log of
the average price, the log of the absolute change in the wholesale price, a control for sale- and bounce-back
prices, which we identify using a sales filter algorithm, and the competition zone of the store. In column 3, we
add a dummy for 9-ending prices as an additional control. In column 4, we focus on regular prices by excluding
the sale- and bounce-back prices. We estimate separate regressions for each product category, clustering the
errors by product. * p < 10%, ** p < 5%, *** p < 1%
97
Table M2. Category-level regressions of small price changes volume, using observations
on private label products
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0295***
(0.0079)
0.0137**
(0.0049)
0.0064
(0.0046)
0.0266*
(0.0137)
Observations
31,617
31,617
31,617
11,090
Bath Soap
Coefficient
(Std.)
0.0096***
(0.0007)
0.0065
(0.0056)
0.0072
(0.0064)
Observations
4,957
4,957
4,957
Bathroom
Tissues
Coefficient
(Std.)
0.0553***
(0.0066)
0.0056
(0.0134)
0.0031
(0.0114)
0.0035
(0.0158)
Observations
18,943
18,943
18,943
6,664
Beer
Coefficient
(Std.)
Observations
Bottled Juice
Coefficient
(Std.)
0.0486***
(0.0053)
0.0438***
(0.0051)
0.0355***
(0.0053)
0.0545***
(0.0099)
Observations
119,432
119,432
119,432
31,569
Canned Soup
Coefficient
(Std.)
0.0256*
(0.0135)
0.0082
(0.008)
0.0082
(0.0078)
0.015
(0.0091)
Observations
55,997
55,997
55,997
17,732
Canned Tuna
Coefficient
(Std.)
0.0776***
(0.0104)
0.0449***
(0.0104)
0.0397***
(0.0113)
0.0474***
(0.0086)
Observations
14,748
14,748
14,748
4,410
Cereals
Coefficient
(Std.)
0.0047
(0.0077)
0.0009
(0.0085)
-0.0109
(0.0102)
0.0491***
(0.0099)
Observations
81,201
81,201
81,201
15,169
Cheese
Coefficient
(Std.)
0.0286***
(0.0066)
0.0146**
(0.0059)
0.0077
(0.0056)
0.013*
(0.0075)
Observations
414,036
414,036
414,036
64,391
Cigarettes
Coefficient
(Std.)
Observations
Cookies
Coefficient
(Std.)
0.0462***
(0.005)
0.0374***
(0.0047)
0.0299***
(0.0044)
0.0504***
(0.0113)
Observations
177,701
177,701
177,701
25,616
Crackers
Coefficient
(Std.)
0.0462***
(0.0051)
0.0423**
(0.0075)
0.034**
(0.0086)
0.054**
(0.013)
Observations
32,249
32,249
32,249
5,487
Dish
Detergent
Coefficient
(Std.)
0.0626***
(0.0077)
0.0575***
(0.007)
0.056***
(0.0078)
0.0647***
(0.0099)
Observations
45,246
45,246
45,246
9,101
Fabric
Softener
Coefficient
(Std.)
0.0641***
(0.0095)
0.0545***
(0.0095)
0.0465***
(0.01)
0.0703***
(0.0098)
Observations
42,022
42,022
42,022
10,860
Front-End-
Candies
Coefficient
(Std.)
Observations
Frozen
Dinners
Coefficient
(Std.)
Observations
98
Table M2. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0395***
(0.0075)
0.0445***
(0.0075)
0.0348***
(0.0064)
0.0725***
(0.0188)
Observations
8,736
8,736
8,736
1,560
Frozen Juices
Coefficient
(Std.)
0.0421***
(0.0076)
0.0365***
(0.0066)
0.0342***
(0.0065)
0.0337*
(0.0164)
Observations
118,148
118,148
118,148
21,915
Grooming
Products
Coefficient
(Std.)
0.0474***
(0.0107)
0.0479**
(0.0098)
0.0398***
(0.0073)
0.081**
(0.0311)
Observations
17,603
17,603
17,603
2,941
Laundry
Detergents
Coefficient
(Std.)
0.0686**
(0.0299)
0.0659**
(0.029)
0.0611**
(0.0272)
0.0707***
(0.0248)
Observations
21,609
21,609
21,609
4,988
Oatmeal
Coefficient
(Std.)
0.0219**
(0.0084)
0.009
(0.0095)
0.0053
(0.0087)
0.0635**
(0.0259)
Observations
21,372
21,372
21,372
3,423
Paper Towels
Coefficient
(Std.)
0.0187*
(0.0252)
0.0373**
(0.0122)
0.034**
(0.0091)
0.0504**
(0.0104)
Observations
18,978
18,978
18,978
3,777
Refrigerated
Juices
Coefficient
(Std.)
0.0248**
(0.011)
0.0188
(0.0115)
0.0128
(0.0115)
0.0417***
(0.0129)
Observations
83,832
83,832
83,832
14,074
Shampoos
Coefficient
(Std.)
0.0023
(0.0233)
0.0078
(0.026)
0.0063
(0.0215)
Observations
1,319
1,319
1,319
Snack
Crackers
Coefficient
(Std.)
0.0525***
(0.0068)
0.0407***
(0.0057)
0.0302***
(0.0052)
0.0688***
(0.0145)
Observations
49,987
49,987
49,987
9,251
Soaps
Coefficient
(Std.)
Observations
Soft Drinks
Coefficient
(Std.)
0.0568***
(0.0075)
0.0231***
(0.0046)
0.0204***
(0.0041)
0.0324***
(0.0085)
Observations
511,920
511,920
511,920
38,424
Toothbrushes
Coefficient
(Std.)
-0.0029
(0.0125)
-0.0034
(0.013)
-0.0086
(0.0121)
0.0425
(0.0323)
Observations
11,756
11,756
11,756
1,876
Toothpastes
Coefficient
(Std.)
0.0735**
(0.02)
0.0533**
(0.016)
0.0388*
(0.016)
0.0235
(0.0394)
Observations
8,565
8,565
8,565
2,363
Average coefficients
0.039
0.030
0.024
0.047
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price
change, using observations on private label products. We drop categories if we do not have at least 500
observations on private label products. The dependent variable is “small price change,” which equals 1 if a
price change of product i in store s at time t is less or equal to 10¢, and 0 otherwise. The main independent
variable is the log of the average sales volume of product i in store s over the sample period. Column 1 reports
the results of baseline regression that includes only the log of the average sales volume and the fixed effects for
months, years, stores, and products. In column 2, we add the following controls: the log of the average price,
the log of the absolute change in the wholesale price, a control for sale- and bounce-back prices, which we
identify using a sales filter algorithm, and the competition zone of the store. In column 3, we add a dummy for
9-ending prices as an additional control. In column 4, we focus on regular prices by excluding the sale- and
bounce-back prices. We estimate separate regressions for each product category, clustering the errors by
product. * p < 10%, ** p < 5%, *** p < 1%
99
Table M3. Category-level regressions of small price changes and sales volume, using
observations on national brand products, prices that survived for 2 weeks
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0166***
(0.0045)
0.0116***
(0.0043)
0.0114***
(0.0043)
0.0077***
(0.0087)
Observations
67,651
67,651
67,651
20,850
Bath Soap
Coefficient
(Std.)
0.0129
(0.0146)
0.0063
(0.0148)
0.0059***
(0.0143)
-0.0203***
(0.0279)
Observations
5,805
5,805
5,805
1,366
Bathroom
Tissues
Coefficient
(Std.)
0.0537***
(0.0097)
0.0176**
(0.0093)
0.0174***
(0.0092)
0.0333***
(0.0111)
Observations
52,445
52,445
52,445
17,009
Beer
Coefficient
(Std.)
0.002***
(0.0006)
0.0043***
(0.0007)
0.0043***
(0.0007)
0.018***
(0.0055)
Observations
187,691
187,691
187,691
12,080
Bottled Juice
Coefficient
(Std.)
0.0367***
(0.0086)
0.0176***
(0.0074)
0.0172***
(0.0075)
0.0308***
(0.0093)
Observations
198,936
198,936
198,936
53,339
Canned Soup
Coefficient
(Std.)
0.0005
(0.0099)
-0.006
(0.0096)
-0.0031***
(0.0093)
0.0137***
(0.008)
Observations
219,520
219,520
219,520
89,102
Canned Tuna
Coefficient
(Std.)
0.0054
(0.0064)
-0.0036
(0.0057)
-0.0038***
(0.0056)
0.0089***
(0.0082)
Observations
108,716
108,716
108,716
30,428
Cereals
Coefficient
(Std.)
0.0111*
(0.0064)
0.0118**
(0.006)
0.0117***
(0.006)
0.0237***
(0.0072)
Observations
123,336
123,336
123,336
69,327
Cheese
Coefficient
(Std.)
0.0085*
(0.0044)
0.0041*
(0.0036)
0.0038***
(0.0036)
0.0143***
(0.0049)
Observations
291,896
291,896
291,896
80,488
Cigarettes
Coefficient
(Std.)
0.0044
(0.0051)
0.0021
(0.0049)
0.0022***
(0.0048)
0***
(0.0055)
Observations
24,553
24,553
24,553
20,692
Cookies
Coefficient
(Std.)
0.0069***
(0.0018)
0.0056***
(0.0019)
0.0055***
(0.0019)
0.0048***
(0.0037)
Observations
296,041
296,041
296,041
61,344
Crackers
Coefficient
(Std.)
0.0006
(0.0034)
0
(0.0032)
0.0003***
(0.0032)
0.0101***
(0.0069)
Observations
110,219
110,219
110,219
23,427
Dish
Detergent
Coefficient
(Std.)
0.0354***
(0.0074)
0.0297***
(0.0066)
0.0297***
(0.0065)
0.029***
(0.0056)
Observations
72,857
72,857
72,857
24,354
Fabric
Softener
Coefficient
(Std.)
0.0177**
(0.0074)
0.0031
(0.0061)
0.0036***
(0.006)
0.0278***
(0.0081)
Observations
75,811
75,811
75,811
24,518
Front-End-
Candies
Coefficient
(Std.)
0.01**
(0.0041)
-0.003*
(0.0033)
-0.0028***
(0.0033)
0.0017***
(0.003)
Observations
148,200
148,200
148,200
77,323
Frozen
Dinners
Coefficient
(Std.)
0.0512***
(0.0069)
0.0389***
(0.0062)
0.0406***
(0.0062)
0.0758***
(0.0105)
Observations
52,893
52,893
52,893
12,287
100
Table M3. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0222***
(0.0026)
0.0163***
(0.0026)
0.0165***
(0.0026)
0.0225***
(0.0039)
Observations
343,898
343,898
343,898
116,594
Frozen Juices
Coefficient
(Std.)
0.0144*
(0.0077)
0.0108**
(0.0072)
0.0123***
(0.007)
0.0239***
(0.009)
Observations
102,582
102,582
102,582
34,179
Grooming
Products
Coefficient
(Std.)
0.0097***
(0.0034)
0.0114***
(0.0033)
0.0116***
(0.0033)
0.0139***
(0.0115)
Observations
99,243
99,243
99,243
21,209
Laundry
Detergents
Coefficient
(Std.)
0.02***
(0.0044)
0.0119***
(0.0036)
0.0121***
(0.0036)
0.0181***
(0.0058)
Observations
116,100
116,100
116,100
40,837
Oatmeal
Coefficient
(Std.)
0.0111
(0.0128)
0.0046
(0.0126)
0.0025***
(0.0118)
0.0556***
(0.0114)
Observations
23,181
23,181
23,181
13,112
Paper Towels
Coefficient
(Std.)
0.028*
(0.0163)
0.0148
(0.0179)
0.016***
(0.0178)
0.0202***
(0.0155)
Observations
46,637
46,637
46,637
8,730
Refrigerated
Juices
Coefficient
(Std.)
0.0181**
(0.0082)
0.0113**
(0.0084)
0.0111***
(0.0082)
0.0222***
(0.0122)
Observations
99,777
99,777
99,777
21,665
Shampoos
Coefficient
(Std.)
0.0102***
(0.0025)
0.0107***
(0.0025)
0.0107***
(0.0025)
0.0234***
(0.008)
Observations
87,969
87,969
87,969
16,041
Snack
Crackers
Coefficient
(Std.)
0.0025
(0.0028)
0.0042**
(0.0028)
0.0042***
(0.0028)
0.021***
(0.005)
Observations
168,620
168,620
168,620
35,998
Soaps
Coefficient
(Std.)
0.0263***
(0.0088)
0.0139**
(0.008)
0.0173***
(0.008)
0.0516***
(0.0117)
Observations
56,710
56,710
56,710
16,872
Soft Drinks
Coefficient
(Std.)
0.0095***
(0.002)
0.0079***
(0.0019)
0.0071***
(0.0019)
0.0121***
(0.004)
Observations
183,882
183,882
183,882
39,371
Toothbrushes
Coefficient
(Std.)
0.0135***
(0.0048)
0.0102***
(0.0049)
0.0097***
(0.0048)
0.0182***
(0.0102)
Observations
49,837
49,837
49,837
12,879
Toothpastes
Coefficient
(Std.)
0.001
(0.004)
0.0002
(0.0039)
0.0003***
(0.0039)
0.0057***
(0.0083)
Observations
99,045
99,045
99,045
27,348
Average coefficients
0.0159
0.0093
0.0095
0.0203
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small
price change, using observations on national brand products. The dependent variable is “small price
change,” which equals 1 if a price change of product i in store s at time t is less or equal to 10¢, and 0
otherwise. The main independent variable is the log of the average sales volume of product i in store s over
the sample period. Column 1 reports the results of baseline regression that includes only the log of the
average sales volume and the fixed effects for months, years, stores, and products. In column 2, we add the
following controls: the log of the average price, the log of the absolute change in the wholesale price, a
control for sale- and bounce-back prices, which we identify using a sales filter algorithm, and the
competition zone of the store. In column 3, we add a dummy for 9-ending prices as an additional control.
In column 4, we focus on regular prices by excluding the sale- and bounce-back prices. We estimate separate
regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
101
Table M4. Category-level regressions of small price changes and sales volume, using
observations on private label products, prices that survived for 2 weeks
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0203***
(0.0111)
0.019***
(0.0107)
0.0182***
(0.0112)
0.0382***
(0.0162)
Observations
6,800
6,800
6,800
3,879
Bath Soap
Coefficient
(Std.)
Observations
Bathroom
Tissues
Coefficient
(Std.)
0.0794***
(0.0263)
-0.0113***
(0.0209)
-0.0113***
(0.0189)
-0.0176***
(0.0067)
Observations
4,013
4,013
4,013
2,276
Beer
Coefficient
(Std.)
Observations
Bottled Juice
Coefficient
(Std.)
0.0154***
(0.012)
0.0228***
(0.0117)
0.0308***
(0.0119)
0.0986***
(0.0282)
Observations
25,921
25,921
25,921
6,676
Canned Soup
Coefficient
(Std.)
0.0013***
(0.0169)
-0.0041***
(0.0133)
-0.0002***
(0.0131)
0.0048***
(0.0178)
Observations
14,259
14,259
14,259
6,208
Canned Tuna
Coefficient
(Std.)
0.137***
(0.033)
0.1061***
(0.0256)
0.1066***
(0.0258)
0.1109***
(0.0336)
Observations
3,913
3,913
3,913
1,494
Cereals
Coefficient
(Std.)
-0.0686***
(0.0265)
-0.0732***
(0.0244)
-0.0814***
(0.0273)
0.0235***
(0.0349)
Observations
17,751
17,751
17,751
3,462
Cheese
Coefficient
(Std.)
0.0115***
(0.0081)
0.009***
(0.008)
0.0082***
(0.0079)
-0.0307***
(0.0134)
Observations
65,783
65,783
65,783
12,270
Cigarettes
Coefficient
(Std.)
Observations
Cookies
Coefficient
(Std.)
0.0387***
(0.0127)
0.0355***
(0.0128)
0.0376***
(0.0127)
0.0503***
(0.0176)
Observations
21,891
21,891
21,891
4,743
Crackers
Coefficient
(Std.)
-0.0006***
(0.0061)
-0.0007***
(0.0056)
-0.0006***
(0.006)
-0.0082***
(0.0284)
Observations
5,439
5,439
5,439
1,344
Dish
Detergent
Coefficient
(Std.)
0.0023***
(0.0175)
0.0085***
(0.0161)
0.012***
(0.016)
-0.0118***
(0.0269)
Observations
12,365
12,365
12,365
2,381
Fabric
Softener
Coefficient
(Std.)
-0.005***
(0.0071)
-0.0079***
(0.0062)
-0.0075***
(0.0059)
0.0126***
(0.0249)
Observations
9,526
9,526
9,526
2,970
Front-End-
Candies
Coefficient
(Std.)
Observations
Frozen
Dinners
Coefficient
(Std.)
Observations
102
Table M4. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0461***
(0.0236)
0.0467***
(0.024)
0.0397***
(0.0211)
0.0328***
(0.0334)
Observations
1,325
1,325
1,325
450
Frozen Juices
Coefficient
(Std.)
0.0025***
(0.0202)
-0.0032***
(0.0181)
-0.0033***
(0.0176)
0.0375***
(0.0199)
Observations
16,000
16,000
16,000
6,338
Grooming
Products
Coefficient
(Std.)
0.0262***
(0.0086)
0.027***
(0.0076)
0.0276***
(0.0077)
0.0849***
(0.0298)
Observations
2,701
2,701
2,701
893
Laundry
Detergents
Coefficient
(Std.)
0.0814***
(0.066)
0.069***
(0.0601)
0.0674***
(0.0555)
0.0153***
(0.0245)
Observations
5,466
5,466
5,466
1,284
Oatmeal
Coefficient
(Std.)
0.0819***
(0.0732)
0.0648***
(0.0573)
0.0636***
(0.0595)
-0.0051***
(0.0532)
Observations
2,342
2,342
2,342
493
Paper Towels
Coefficient
(Std.)
0.1087***
(0.0483)
0.0922***
(0.0523)
0.0834***
(0.0476)
0.069***
(0.0399)
Observations
1,562
1,562
1,562
513
Refrigerated
Juices
Coefficient
(Std.)
-0.0393***
(0.0266)
-0.0583***
(0.0232)
-0.06***
(0.0224)
-0.0653***
(0.0435)
Observations
9,188
9,188
9,188
2,040
Shampoos
Coefficient
(Std.)
-0.2464***
(0.1073)
-0.1186***
(0.1087)
-0.1181***
(0.1089)
0***
(0)
Observations
224
224
224
58
Snack
Crackers
Coefficient
(Std.)
-0.0036***
(0.0136)
-0.0088***
(0.013)
-0.01***
(0.013)
-0.0395***
(0.0204)
Observations
7,907
7,907
7,907
2125
Soaps
Coefficient
(Std.)
Observations
Soft Drinks
Coefficient
(Std.)
0.0765***
(0.0181)
0.0082***
(0.006)
0.0081***
(0.0058)
0.0035***
(0.0064)
Observations
59,955
59,955
59,955
10,618
Toothbrushes
Coefficient
(Std.)
-0.0185***
(0.0133)
-0.0205***
(0.0132)
-0.0215***
(0.0129)
-0.07***
(0.0368)
Observations
2,348
2,348
2,348
816
Toothpastes
Coefficient
(Std.)
-0.0576***
(0.0472)
-0.0386***
(0.0342)
-0.0364***
(0.0335)
-0.0096***
(0.051)
Observations
1,800
1,800
1,800
691
Average coefficients
0.0126
0.0071
0.0066
0.0141
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small
price change, using observations on national brand products. We drop categories if we do not have at least
500 observations on private-label products. The dependent variable is “small price change,” which equals
1 if a price change of product i in store s at time t is less or equal to 10¢, and 0 otherwise. The main
independent variable is the log of the average sales volume of product i in store s over the sample period.
Column 1 reports the results of baseline regression that includes only the log of the average sales volume
and the fixed effects for months, years, stores, and products. In column 2, we add the following controls:
the log of the average price, the log of the absolute change in the wholesale price, a control for sale- and
bounce-back prices, which we identify using a sales filter algorithm, and the competition zone of the store.
In column 3, we add a dummy for 9-ending prices as an additional control. In column 4, we focus on
regular prices by excluding the sale- and bounce-back prices. We estimate separate regressions for each
product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
103
Appendix N. Sales volumes, small price changes, and holidays
Levy et al. (2010) argue that menu costs are higher during the holiday season than at
other times. As they note, store traffic is higher during holidays than other times and,
consequently, tasks such as restocking shelves, running cash registers, cleaning and
bagging, etc., become more urgent. Therefore, the opportunity cost of price adjustment
increases during holiday periods.
If menu costs are higher, then we should observe fewer small price changes, possibly
weakening the correlation between sales volumes and small price changes. To explore
this, we focus on the holiday period, which, following Warner and Barsky (1995) and
Levy et al. (2010), we define as the period starting the week before Thanksgiving through
the week of Christmas, a total of six weeks.
Table N1 presents the results of regressions equivalent to the regressions in Table 3
in the paper. This time, however, we use only observations on the holiday period, defined
as above. The regressions take the following form:
, , , , ,
,,
ln( )
i s t i s i s t
t t s i i s t
small price change average sales volume
month year u
X
(N1)
where small price change is a dummy that equals 1 if a price change of product i in store
s at time t is less or equal to 10¢, and 0 otherwise. The average sales volume is the
average sales volume of product i in store s over the sample period. X is a matrix of other
control variables. Month and year are fixed effects for the month and the year of the price
change.
and
are fixed effects for stores and products, respectively, and u is an i.i.d
error term. We estimate separate regressions for each product category, clustering the
errors by product.
As we do in the paper, we use observations on price changes only if we observe the
price in both weeks t and t + 1 and the post change price remained unchanged for at least
2 weeks. The values in Table N1 are the coefficients of the log of the average sales
volume when we use the sample of national brands. In column 1, the control variables are
the log of the average sales volume, and the dummies for months, years, stores, and
products. We find that 19 out of the 29 coefficients of the log of the average sales volume
are positive. Out of the 19 positive coefficients, 4 are statistically significant and 5 are
marginally statistically significant. Out of the 10 negative coefficients, 3 are statistically
104
significant and 4 more are marginally significant. The average coefficient is 0.010,
suggesting that a 1% increase in the sales volume is associated with a 1.0% increase in
the likelihood of a small price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). 20 of the 29 coefficients
are positive. 5 of the positive coefficients are statistically significant and 4 are marginally
significant. Out of the 9 negative coefficients, 3 are statistically significant, and 2 more
are marginally significant. The average coefficient is 0.005, suggesting that a 1% increase
in the sales volume is associated with a 0.5% increase in the likelihood of a small price
change.
In column 3, we add a control for 9-ending prices. We find that 19 out of the 29
coefficients of the log of the average sales volume are positive. Out of the 19 positive
coefficients, 5 are statistically significant and 3 are marginally statistically significant.
Out of the 10 negative coefficients, 3 are statistically significant, and 2 more are
marginally significant. The average coefficient is 0.006, suggesting that a 1% increase in
the sales volume is associated with a 0.6% increase in the likelihood of a small price
change.
As a further control for the possible effects of sales on the results we report, in
column 4 we focus on regular prices by excluding all sale- and bounce-back prices. When
we focus on regular prices, 18 of the 29 coefficients are positive. 7 of them are
statistically significant, and 2 more are marginally significant. Out of the 11 negative
coefficients, 3 are statistically significant, and 2 more are marginally significant. The
average coefficient is 0.008, suggesting that a 1% increase in the sales volume is
associated with a 0.8% increase in the likelihood of a small price change.
We thus find that the positive correlation between sales volumes and small price
changes seems to be weaker during the holiday periods, which is consistent with a high
cost of price changes during holidays (Levy et al. 2010). However, because the number
of observations is relatively small, these results require further research.
105
Table N1. Category-level regressions of small price changes using observations on
products sold in the Thanksgiving-Christmas holiday period
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0211**
(0.0112)
0.0156**
(0.0105)
0.0161***
(0.0105)
0.0352***
(0.0171)
Observations
8,769
8,769
8,769
2,982
Bath Soap
Coefficient
(Std.)
-0.001
(0.0144)
0.0136*
(0.0151)
0.0106***
(0.0164)
0.0402
(0.1183)
Observations
622
622
622
116
Bathroom
Tissues
Coefficient
(Std.)
0.0555***
(0.0224)
0.0007
(0.0185)
0.0127***
(0.0177)
0.0078
(0.0259)
Observations
6,334
6,334
6,334
1,685
Beer
Coefficient
(Std.)
-0.0005*
(0.0006)
0.0007*
(0.0005)
0.0007***
(0.0005)
0.0116*
(0.0109)
Observations
16,773
16,773
16,773
669
Bottled Juice
Coefficient
(Std.)
0.0111*
(0.0099)
0.0042
(0.0096)
0.0038***
(0.0097)
-0.001
(0.0134)
Observations
26,881
26,881
26,881
9,610
Canned Soup
Coefficient
(Std.)
-0.0123*
(0.0104)
-0.0158**
(0.0103)
-0.0169***
(0.0098)
0.0097
(0.0123)
Observations
28,293
28,293
28,293
8,944
Canned Tuna
Coefficient
(Std.)
0.0006
(0.0103)
-0.0034
(0.0103)
-0.0047***
(0.0103)
0
(0.0126)
Observations
12,860
12,860
12,860
3,436
Cereals
Coefficient
(Std.)
0.0204**
(0.0148)
0.0175*
(0.0139)
0.0179***
(0.0139)
0.0226**
(0.013)
Observations
15,947
15,947
15,947
10,547
Cheese
Coefficient
(Std.)
0.0065*
(0.007)
0.002
(0.0065)
0.0019***
(0.0065)
0.0016
(0.0099)
Observations
42,339
42,339
42,339
10,048
Cigarettes
Coefficient
(Std.)
-0.0132*
(0.0128)
-0.0101*
(0.0097)
-0.0101***
(0.0096)
-0.0096*
(0.0095)
Observations
2,403
2,403
2,403
2,241
Cookies
Coefficient
(Std.)
0.0035
(0.0051)
0.0029
(0.005)
0.0022***
(0.0048)
-0.0018
(0.0071)
Observations
21,508
21,508
21,508
7,429
Crackers
Coefficient
(Std.)
0.0048*
(0.0052)
0.0032
(0.0054)
0.0041***
(0.0055)
-0.008*
(0.0088)
Observations
7,263
7,263
7,263
1,861
Dish
Detergent
Coefficient
(Std.)
0.0376***
(0.009)
0.0308***
(0.0084)
0.0325***
(0.0082)
0.0089**
(0.0061)
Observations
10,342
10,342
10,342
3,385
Fabric
Softener
Coefficient
(Std.)
0.008
(0.0182)
-0.0117
(0.0148)
-0.0112***
(0.0149)
-0.0135
(0.0171)
Observations
8,121
8,121
8,121
3,373
Front-End-
Candies
Coefficient
(Std.)
-0.0121**
(0.0085)
-0.0113***
(0.0045)
-0.0069***
(0.0045)
-0.0031
(0.0038)
Observations
15,148
15,148
15,148
6,289
Frozen
Dinners
Coefficient
(Std.)
0.0132*
(0.014)
0.0056
(0.0142)
0.0038***
(0.014)
0.0099**
(0.0089)
Observations
3,534
3,534
3,534
596
106
Table N1. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0069*
(0.0068)
-0.0052
(0.0078)
-0.0055***
(0.0076)
-0.0042
(0.0096)
Observations
21,998
21,998
21,998
9,784
Frozen Juices
Coefficient
(Std.)
-0.0021
(0.0134)
0.0003
(0.015)
-0.0027***
(0.0144)
0.0017
(0.0231)
Observations
13,388
13,388
13,388
4,499
Grooming
Products
Coefficient
(Std.)
0.0041
(0.008)
0.0068
(0.0087)
0.0067***
(0.0085)
0.0083
(0.0161)
Observations
9,078
9,078
9,078
2,327
Laundry
Detergents
Coefficient
(Std.)
0.0186**
(0.0124)
0.0136*
(0.0107)
0.0137***
(0.0107)
0.0194**
(0.0118)
Observations
13,130
13,130
13,130
5,979
Oatmeal
Coefficient
(Std.)
0.0219**
(0.0237)
0.0104
(0.0195)
0.0106***
(0.0191)
0.0787***
(0.0311)
Observations
2,854
2,854
2,854
1,082
Paper Towels
Coefficient
(Std.)
0.0636**
(0.037)
0.0578**
(0.0359)
0.0581***
(0.0361)
0.0614**
(0.038)
Observations
5,633
5,633
5,633
1,284
Refrigerated
Juices
Coefficient
(Std.)
0.0026
(0.0143)
0.0027
(0.014)
0.0025***
(0.0138)
0.0259**
(0.0184)
Observations
15,643
15,643
15,643
4,026
Shampoos
Coefficient
(Std.)
-0.0042**
(0.0029)
0.0009
(0.0031)
0.0009***
(0.0031)
0.0074
(0.011)
Observations
8,669
8,669
8,669
884
Snack
Crackers
Coefficient
(Std.)
-0.0053*
(0.0046)
-0.0054**
(0.005)
-0.0047***
(0.0049)
-0.0022
(0.004)
Observations
20,929
20,929
20,929
4,015
Soaps
Coefficient
(Std.)
0.0422***
(0.0171)
0.0371
(0.0171)
0.042***
(0.0159)
0.0051
(0.0289)
Observations
4,592
4,592
4,592
1,032
Soft Drinks
Coefficient
(Std.)
0.0261***
(0.0072)
0.008**
(0.0045)
0.0106***
(0.005)
-0.0233***
(0.0078)
Observations
31,935
31,935
31,935
5,062
Toothbrushes
Coefficient
(Std.)
-0.0023
(0.0105)
-0.0028***
(0.0101)
-0.0042***
(0.0107)
-0.0199**
(0.0142)
Observations
6,748
6,748
6,748
2,056
Toothpastes
Coefficient
(Std.)
-0.0307***
(0.0086)
-0.0227***
(0.0081)
-0.0216***
(0.0079)
-0.0386***
(0.0129)
Observations
12,819
12,819
12,819
5,182
Average coefficients
0.0098
0.0050
0.0056
0.0079
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small
price change, using observations on products sold during the holiday period. We define the holiday period
as starting in the week prior to Thanksgiving and continuing through Christmas. The dependent variable
is “small price change,” which equals 1 if a price change of product i in store s at time t is less or equal to
10¢, and 0 otherwise. The main independent variable is the log of the average sales volume of product i
in store s over the sample period. Column 1 reports the results of baseline regression that includes only
the log of the average sales volume and the fixed effects for months, years, stores, and products. In column
2, we add the following controls: the log of the average price, the log of the absolute change in the
wholesale price, a control for sale- and bounce-back prices, which we identify using a sales filter
algorithm and the competition zone of the store. In column 3, we add a dummy for 9-ending prices as an
additional control. In column 4, we focus on regular prices by excluding the sale- and bounce-back prices.
107
We estimate separate regressions for each product category, clustering the errors by product. * p < 10%,
** p < 5%, *** p < 1%
108
Appendix O. The likelihood of a price change, irrespective of its size
In the paper, we show that in Barro’s (1972) menu cost model, an increase in the sales
volume reduces the width of the S-s band, leading to (a) more frequent small price changes,
and (b) more frequent price changes (of any size). In the paper, we report evidence supporting
the first prediction. In this appendix, we show that the data supports the second prediction as
well.
As a first test, we look within categories. Table O1 presents the results of regressions
equivalent to the regressions in Table 3 in the paper. The regressions take the form:
ℎ (O1)
where price change is a dummy that equals 1 if the price of product i in store s changed
at time t, and 0 otherwise. The average sales volume is the average sales volume of
product i in store s over the sample period. X is a matrix of other control variables. Month
and year are fixed effects for the month and the year of the price change.
and
are
fixed effects for stores and products, respectively, and u is an i.i.d error term. We
estimate separate regressions for each product category, clustering the errors by product.
As we do in the paper, we use observations on price changes only if we observe the price
in both weeks t and t + 1 and the post change price remained unchanged for at least 2
weeks.
The values in the table are the coefficients of the log of the average sales volume. In
column 1, the control variables are the log of the average sales volume, and dummies for
months, years, stores, and products. We find that 24 of the 29 coefficients of the average
sales volume are positive. 20 of the 24 positive coefficients are statistically significant.
The 5 negative coefficients are also statistically significant. The average coefficient is
0.004, suggesting that a 1% increase in the average sales volume is associated with a
0.4% increase in the likelihood of a price change.
In column 2, we add controls for the log of the average price, the log of the absolute
change in the wholesale price, and a control for sale- and bounce-back prices, which we
identify using the sales filter algorithm of Fox and Syed (2016). We find that 24 of the 29
coefficients of the average sales volume are positive. 21 of the 24 positive coefficients
109
are statistically significant. 3 out of the 5 negative coefficients are statistically significant.
The average coefficient is 0.005, suggesting that a 1% increase in the average sales
volume is associated with a 0.5% increase in the likelihood of a price change.
In column 3, we add a control for 9-ending prices. 24 of the 29 coefficients of the
average sales volume are positive. 21 of the 24 positive coefficients are statistically
significant. 3 out of the 5 negative coefficients are statistically significant. The average
coefficient is 0.005, suggesting that a 1% increase in the average sales volume is
associated with a 0.5% increase in the likelihood of a price change.
As a further control for the effects of sales on the results, in column 4 we focus on
regular prices by excluding all sale and bounce-back prices. 27 of the 29 coefficients are
positive. 25 of the positive coefficients are statistically significant, and 1 more is
marginally statistically significant. The average coefficient is 0.002, suggesting that a 1%
increase in the sales volume is associated with a 0.2% increase in the likelihood of a price
change.
As a second test, we conduct a product-level test, similar to the test that its results
are reported in Table 4 in the paper. To conduct the test, we calculate for each product in
each of the 29 product categories the average weekly sales volume and the share of small
price changes in each store it was offered. Many products in the sample were offered for
only short periods of time, or only in a small number of stores. To avoid biases, we drop
products for which we do not have information for at least 30 stores.
Using these data, we estimate for each product in each category, an OLS regression
with robust standard errors. The dependent variable is the share of price changes out of
all observations for the product in each store. The independent variable is the average
sales volume of the product in each store. The estimation results are reported in Table
O2.
Column 1 presents for each product category, the average of the estimated
coefficients. Column 2 presents the total number of coefficients. Column 3 presents the
percentage of the positive coefficients. Column 4 presents the number of statistically
significant coefficients. Column 5 presents the percentage of positive and significant
coefficients out of the total number of statistically significant coefficients.
According to the figures in the table, the average coefficients are positive for all 29
110
product categories. Further, the number of positive coefficients far exceeds the number of
negative coefficients: On average, 83.4% of all the coefficients are positive.
Focusing on statistically significant coefficients, we find a far greater number of
positive coefficients than negative coefficients. On average, 90.5% of all statistically
significant coefficients are positive. In other words, for the overwhelming majority of the
individual products in our sample, we find a positive relationship between sales volume
and the likelihood of a price change.
In summary, we find that as predicted by Barro’s (1972) model, an increase in the
sales volume is associated with an increase in the likelihood of a price change, in addition
to an increase in the likelihood of a small price change.
111
Table O1. The likelihood of a price change
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0095***
(0.0006)
0.0102***
(0.0007)
0.0103***
(0.0007)
0.004***
(0.0003)
Observations
3,060,156
3,019,519
3,019,519
2,615,923
Bath Soap
Coefficient
(Std.)
0.0097***
(0.0008)
0.0103***
(0.0009)
0.0102***
(0.0009)
0.0037***
(0.0004)
Observations
418,097
402,960
402,960
336,180
Bathroom
Tissues
Coefficient
(Std.)
-0.0032***
(0.0008)
-0.0026***
(0.0008)
-0.0026***
(0.0008)
0.0002***
(0.0004)
Observations
1,159,016
1,149,177
1,149,177
831,301
Beer
Coefficient
(Std.)
0.0307***
(0.0016)
0.0273***
(0.0014)
0.0293***
(0.0014)
0.002***
(0.0003)
Observations
1,970,266
1,940,556
1,940,556
1,174,512
Bottled Juice
Coefficient
(Std.)
-0.0024***
(0.0007)
0.0005***
(0.0007)
0.0006***
(0.0007)
0.0008***
(0.0003)
Observations
4,325,024
4,288,625
4,288,625
3,205,484
Canned Soup
Coefficient
(Std.)
0.0017***
(0.0006)
0.0026***
(0.0006)
0.0025***
(0.0006)
0.0012***
(0.0003)
Observations
5,551,684
5,518,976
5,518,976
4,539,808
Canned Tuna
Coefficient
(Std.)
0.0032***
(0.0009)
0.0052***
(0.001)
0.0053***
(0.001)
0.0026***
(0.0004)
Observations
2,403,558
2,383,604
2,383,604
1,875,309
Cereals
Coefficient
(Std.)
-0.001***
(0.0003)
-0.0014***
(0.0003)
-0.0014***
(0.0003)
-0.0003***
(0.0002)
Observations
4,751,202
4,714,708
4,714,708
4,127,993
Cheese
Coefficient
(Std.)
0.0013***
(0.0005)
0.0029***
(0.0005)
0.0032***
(0.0005)
0.0011***
(0.0003)
Observations
6,810,625
6,763,438
6,763,438
4,961,570
Cigarettes
Coefficient
(Std.)
0.0069***
(0.0003)
0.0068***
(0.0003)
0.0068***
(0.0003)
0.0061***
(0.0003)
Observations
1,810,615
1,774,701
1,774,701
1,742,604
Cookies
Coefficient
(Std.)
0.004***
(0.0004)
0.0055***
(0.0004)
0.0057***
(0.0004)
0.0022***
(0.0002)
Observations
7,635,071
7,556,886
7,556,886
5,821,862
Crackers
Coefficient
(Std.)
0.0103***
(0.0011)
0.0128***
(0.0012)
0.013***
(0.0012)
0.0044***
(0.0004)
Observations
2,245,703
2,224,614
2,224,614
1,588,598
Dish
Detergent
Coefficient
(Std.)
0.0034***
(0.0007)
0.0042***
(0.0007)
0.0042***
(0.0007)
0.0019***
(0.0003)
Observations
2,183,582
2,161,641
2,161,641
1,744,461
Fabric
Softener
Coefficient
(Std.)
0.0021***
(0.0005)
0.0032***
(0.0007)
0.0032***
(0.0006)
0.0018***
(0.0003)
Observations
2,296,612
2,271,465
2,271,465
1,877,718
Front-End-
Candies
Coefficient
(Std.)
0.0022***
(0.0003)
0.0039***
(0.0004)
0.0039***
(0.0004)
0.0033***
(0.0003)
Observations
4,475,750
4,441,325
4,441,325
3,948,230
Frozen
Dinners
Coefficient
(Std.)
0.0005***
(0.0007)
0.0028***
(0.0007)
0.0027***
(0.0007)
0.0027***
(0.0004)
Observations
1,654,053
1,634,182
1,634,182
1,061,943
112
Table O1. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0025***
(0.0004)
0.0068***
(0.0005)
0.0068***
(0.0005)
0.0044***
(0.0003)
Observations
7,232,080
7,164,744
7,164,744
5,163,065
Frozen Juices
Coefficient
(Std.)
-0.002***
(0.0008)
-0.0004***
(0.0007)
-0.0004***
(0.0007)
0.001***
(0.0005)
Observations
2,387,420
2,373,678
2,373,678
1,700,508
Grooming
Products
Coefficient
(Std.)
0.011***
(0.0005)
0.0107***
(0.0005)
0.0109***
(0.0005)
0.003***
(0.0002)
Observations
4,065,694
3,980,757
3,980,757
2,937,437
Laundry
Detergents
Coefficient
(Std.)
0.0023***
(0.0005)
0.0035***
(0.0006)
0.0036***
(0.0006)
0.0017***
(0.0003)
Observations
3,303,174
3,258,164
3,258,164
2,616,474
Oatmeal
Coefficient
(Std.)
0.0008***
(0.0009)
0.0012***
(0.0012)
0.0012***
(0.0012)
0.0013***
(0.0007)
Observations
981,263
973,819
973,819
839,966
Paper Towels
Coefficient
(Std.)
0.0006***
(0.001)
0***
(0.001)
0***
(0.001)
0***
(0.0005)
Observations
948,871
937,197
937,197
672,784
Refrigerated
Juices
Coefficient
(Std.)
-0.0025***
(0.0007)
-0.0019***
(0.0007)
-0.0015***
(0.0007)
0.0008***
(0.0004)
Observations
2,182,989
2,165,804
2,165,804
1,363,980
Shampoos
Coefficient
(Std.)
0.0095***
(0.0003)
0.0092***
(0.0003)
0.0094***
(0.0003)
0.0026***
(0.0001)
Observations
4,676,790
4,535,601
4,535,601
3,330,183
Snack
Crackers
Coefficient
(Std.)
0.0046***
(0.0006)
0.0058***
(0.0007)
0.006***
(0.0007)
0.0017***
(0.0003)
Observations
3,515,192
3,484,645
3,484,645
2,501,842
Soaps
Coefficient
(Std.)
0.0005***
(0.0005)
0.0009***
(0.0006)
0.0009***
(0.0006)
0.0013***
(0.0003)
Observations
1,835,196
1,810,103
1,810,103
1,464,608
Soft Drinks
Coefficient
(Std.)
0.0019***
(0.0002)
0.0021***
(0.0002)
0.0024***
(0.0002)
0.0013***
(0.0002)
Observations
10,807,191
10,702,594
10,702,594
5,499,044
Toothbrushes
Coefficient
(Std.)
0.0107***
(0.0006)
0.011***
(0.0007)
0.0111***
(0.0007)
0.0049***
(0.0004)
Observations
1,854,983
1,825,943
1,825,943
1,354,698
Toothpastes
Coefficient
(Std.)
0.007***
(0.0005)
0.0072***
(0.0006)
0.0073***
(0.0006)
0.0031***
(0.0003)
Observations
3,003,392
2,964,185
2,964,185
2,234,909
Average coefficients
0.0043
0.0052
0.0053
0.0022
Notes: The table reports the results of category-level fixed effect regressions of the probability of a price change. The
dependent variable is “price change,” of product i in store s at time t which equals 1 if a price of product i in store s
changes at time t and 0 otherwise. The main independent variable is the log of the average sales volume of product i
in store s over the sample period. Column 1 reports the results of the baseline regression that includes only the average
sales volume and the fixed effects for months, years, stores, and products. In column 2, we add the following controls:
the log of the average price, the log of the absolute change in the wholesale price, and a control for sale- and bounce-
back prices, which we identify using a sales filter algorithm. In column 3, we add a dummy for 9-ending prices as an
additional control. In column 4, we focus on regular prices by excluding the sale- and bounce-back prices. We estimate
separate regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
113
Table O2. Product-level regressions of the % of small price changes and sales volume by
categories, including controls
Product
Category
Average
coefficient
(1)
No. of
coefficients
(2)
% positive
coefficients
(3)
No. of significant
coefficients
(4)
% positive and
significant
coefficients
(5)
Analgesics
0.0037
461
95.01%
315
99.68%
Bath Soaps
0.0050
109
90.83%
59
100.00%
Bathroom tissues
0.0021
112
59.82%
39
53.85%
Beers
0.0079
414
96.86%
330
100.00%
Bottled juices
0.0061
418
70.33%
216
79.17%
Canned soups
0.0064
368
73.37%
164
85.98%
Canned tuna
0.0090
219
83.56%
138
92.03%
Cereals
0.0012
408
62.99%
139
67.63%
Cheese
0.0053
529
72.59%
286
84.27%
Cigarettes
0.0015
282
92.91%
163
100.00%
Cookies
0.0088
877
85.52%
565
97.70%
Crackers
0.0115
248
91.94%
192
96.35%
Dish detergents
0.0056
247
87.45%
150
94.67%
Fabric softeners
0.0046
280
84.29%
143
93.01%
Front end candies
0.0148
375
78.93%
196
94.90%
Frozen dinners
0.0110
232
96.55%
175
100.00%
Frozen entrees
0.0114
750
94.80%
538
99.26%
Frozen juices
0.0114
155
90.32%
92
96.74%
Grooming products
0.0094
965
91.40%
626
98.40%
Laundry detergents
0.0025
514
80.16%
251
91.24%
Oatmeal
0.0039
85
74.12%
42
88.10%
Paper towels
0.0034
103
59.22%
41
60.98%
Refrigerated juices
0.0030
192
69.27%
79
64.56%
Shampoos
0.0077
1,661
87.96%
834
98.92%
Snack crackers
0.0094
352
89.77%
235
95.74%
Soaps
0.0078
270
85.56%
145
97.93%
Soft drinks
0.0130
1,184
89.10%
778
96.27%
Toothbrushes
0.0103
333
93.39%
234
98.72%
Toothpastes
0.0089
467
91.86%
299
99.00%
Average
0.0071
435
83.44%
257
90.52%
Notes: Results of product-level regression. The dependent variable in all regressions is the share of price changes for each
product at each store. For each product category, column 1 presents the average of the estimated coefficients of the log of the
average sales volumes. The regressions also include controls for the median income, the share of ethnic minorities, the
unemployment rate, and the pricing zone of the store. Column 2 presents the total number of coefficients. Column 3 presents
the % of positive coefficients out of all coefficients. Column 4 presents the total number of coefficients that are statistically
significant at the 5% level. Column 5 presents the % of coefficients that are positive and statistically significant, at the 5%
level.
114
Appendix P. Controlling for peak days
Bonomo et al. (2022) show that the majority of price changes occur during “peak
days.” Following their definition, for each category in each store we identify peak weeks
as the subset of the most active days that jointly account for one-half of all price changes
in a store over the entire sample period. We then define a dummy for peak weeks that
equals 1 if a week is a peak week and 0 otherwise.
In Tables P1–P4, we present the results of estimating category-level regressions of
the following form:
(P1)
where small price change is a dummy that equals 1 if a price change of product i in store
s at time t is less or equal to 10¢, and 0 otherwise. The average sales volume is the
average sales volume of product i in store s over the sample period. The variable
is a dummy that equals 1 if week t in store s is a peak day X is a matrix of
other control variables. Month and year are fixed effects for the month and the year of the
price change.
and
are fixed effects for stores and products, respectively, and u is
an i.i.d error term. We estimate separate regressions for each product category, clustering
the errors by product. As we do in the paper, we use observations on price changes only
if we observe the price in both week t and t + 1 and the post-change price remained
unchanged for at least 2 weeks.
The coefficient columns in the sales volume and the revenue panels of Table P1
report the coefficients of sales volume and peak-week, respectively in a regression that
also includes fixed effects for months, years, stores and products. 27 of the sales volume
coefficients are positive. 18 of the coefficients are statistically significant and 2 more are
marginally significant. The average coefficient is 0.017, suggesting that a 1% increase in
the sales volume is associated with a 1.7% increase in the likelihood of a small price
change.
11 of the coefficients of the peak-week dummy are not statistically significant. 13 are
negative and statistically significant and only 5 are positive and statistically significant.
115
The results therefore suggest that the positive correlation between sales volumes and
small price changes holds also when we control for peak weeks, but that small price
changes are not more common on peak weeks than on other weeks.
Table P2 reports the results when we add controls for the log of the average price,
the log of the absolute change in the wholesale price, a control for sale- and bounce-back
prices (which we identify using the sales filter algorithm of Fox and Syed 2016), and
Dominick’s pricing zone. In Table P3, we also add a control for 9-ending prices. In both
tables, we find that 26 of the 29 coefficients are positive. 14 of the positive coefficients
are statistically significant, and two more are marginally significant. The average
coefficient is 0.010, suggesting that a 1% increase in the sales volume is associated with a
1.0% increase in the likelihood of a small price change.
As a further control for the effects of sales on the results, in Table P4 we focus on
regular prices by excluding all sale- and bounce-back prices. When we focus on regular
prices, we find that 27 of the 29 coefficients are positive. 18 are statistically significant,
and 5 more are marginally significant. The average coefficient is 0.021, suggesting that a
1% increase in the sales volume is associated with a 2.1% increase in the likelihood of a
small price change.
Thus, adding control for peak weeks does not change our main results regarding the
correlation between sales volumes and small price changes.
116
Table P1. Controlling for peak days. Baseline regressions
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change. The
dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less or equal
to 10¢, and 0 otherwise. The main independent variables are the log of average sales volume of product i in store s over the
sample period and a dummy for peak days that equals 1 if it is one of the weeks with the largest number of price changes,
so that all the peak weeks account for 50% of all the price changes. The regressions also include fixed effects for stores,
products, months, and years. We estimate separate regressions for each product category, clustering the errors by product.
* p < 10%, ** p < 5%, *** p < 1%
Category
Sales Volume
Peak days
No. of
Observations
Coefficient
Std.
Coefficient
Std.
Analgesics
0.0168***
0.0040
0.003
0.0117
74,451
Bath Soap
0.0093
0.0128
0.0202
0.0127
6,650
Bathroom Tissues
0.0576***
0.0087
0.0036
0.0131
56,458
Beer
0.0019***
0.0006
0.0065***
0.0015
187,691
Bottled Juice
0.0366***
0.0079
-0.0508***
0.0089
224,857
Canned Soup
0.0033
0.0090
-0.0567***
0.0098
233,779
Canned Tuna
0.0094
0.0066
0.0151
0.0108
112,629
Cereals
0.0072
0.0066
-0.0621***
0.0141
141,087
Cheese
0.0117***
0.0040
-0.0545***
000.01
357,679
Cigarettes
0.0031
0.0049
0.0824***
00.005
24,553
Cookies
0.01***
0.0019
-0.0264***
0.0079
317,932
Crackers
0.0047
0.0033
-0.0496***
0.0128
115,658
Dish Detergent
0.03***
0.0071
-0.0127
0.0168
85,222
Fabric Softener
0.0139**
0.0069
0.0274**
0.0128
85,337
Front-End-Candies
0.0104***
0.0040
-0.0177
0.0143
148,200
Frozen Dinners
0.0494***
0.0068
0.0163*
0.0084
52,893
Frozen Entrees
0.0258***
0.0026
-0.0829***
0.0061
345,223
Frozen Juices
0.0173**
0.0073
-0.0562***
0.0168
118,582
Grooming Products
0.0091***
0.0033
0.0093***
0.0036
101,944
Laundry Detergents
0.021***
0.0046
0.0083
0.0116
121,566
Oatmeal
0.0189
0.0125
-0.086***
0.0217
25,523
Paper Towels
0.0294*
0.0156
-0.0887***
0.0185
48,199
Refrigerated Juices
0.0142*
0.0077
-0.0278***
00.011
108,965
Shampoos
0.0079***
0.0025
0.0245***
0.0033
88,193
Snack Crackers
0.002
0.0027
0.0018
0.0134
176,527
Soap
0.0277***
0.0089
-0.0355***
0.0117
56,725
Soft Drinks
0.0307***
0.0044
-0.0431***
0.0085
243,837
Toothbrushes
0.0128***
0.0046
0.0053
0.0098
52,185
Toothpastes
0.0009
0.0040
-0.0029
0.0093
100,845
Average
0.0170
0.0061
-0.0183
0.0109
131,496
117
Table P2. Controlling for peak days with additional controls
Category
Sales Volume
Peak days
No. of
Observations
Coefficient
Std.
Coefficient
Std.
Analgesics
0.013***
0.0039
-0.0065
0.0131
74,451
Bath Soap
0.0056
0.0129
0.0097
0.0098
6,650
Bathroom Tissues
0.0195**
0.0083
-0.0068
0.0130
56,458
Beer
0.0042***
0.0007
0.0049***
0.0011
187,691
Bottled Juice
0.02***
0.0069
-0.0343***
0.0085
224,857
Canned Soup
-0.0035
0.0087
-0.0344***
0.0094
233,779
Canned Tuna
-0.0012
0.0059
0.0139
0.0110
112,629
Cereals
0.0084
0.0065
-0.1023***
0.0146
141,087
Cheese
0.0074**
0.0034
-0.0536***
0.0097
357,679
Cigarettes
0.0008
0.0047
0.0818***
0.0051
24,553
Cookies
0.009***
0.0020
-0.0326***
0.0079
317,932
Crackers
0.0041
0.0031
-0.0476***
0.0129
115,658
Dish Detergent
0.0255***
0.0063
-0.034**
0.0156
85,222
Fabric Softener
0.0018
0.0057
0.0145
0.0110
85,337
Front-End-Candies
-0.0036
0.0033
0.0227*
0.0121
148,200
Frozen Dinners
0.0331***
0.0060
0.0496***
0.0089
52,893
Frozen Entrees
0.0189***
0.0026
-0.0429***
0.0058
345,223
Frozen Juices
0.0121*
0.0069
-0.0541***
0.0156
118,582
Grooming Products
0.011***
0.0033
0.0005
0.0033
101,944
Laundry Detergents
0.0128***
0.0039
-0.0004
0.0105
121,566
Oatmeal
0.0111
0.0122
-0.0598***
0.0214
25,523
Paper Towels
0.0171
0.0172
-0.0688***
0.0193
48,199
Refrigerated Juices
0.0065
0.0079
-0.0201*
0.0108
108,965
Shampoos
0.0089***
0.0025
0.0199***
0.0031
88,193
Snack Crackers
0.0035
0.0027
0.0012
0.0135
176,527
Soap
0.0152*
0.0081
-0.0331***
0.0105
56,725
Soft Drinks
0.0145***
0.0019
-0.0333***
0.0075
243,837
Toothbrushes
0.0093**
0.0047
0.0082*
0.0097
52,185
Toothpastes
0.001
0.0038
-0.0183**
0.0088
100,845
Average
0.0099
0.0057
-0.0157
0.0105
131,496
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change. The
dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less or equal
to 10¢, and 0 otherwise. The main independent variables are the log of average sales volume of product i in store s over the
sample period and a dummy for peak days that equals 1 if it is one of the weeks with the largest number of price changes,
so that all the peak weeks account for 50% of all the price changes. The regressions also include the following independent
variables: the products’ average price, percentage changes in the wholesale price and a dummy for sale and bounce-back
prices, as well as fixed effects for years, months, stores, and products. We estimate separate regressions for each product
category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
118
Table P3. Bonomo regressions – including a control for 9-ending prices
Category
Sales Volume
Peak days
No. of
Observations
Coefficient
Std.
Coefficient
Std.
Analgesics
0.0128***
0.0038
-0.0076**
0.0129
74,451
Bath Soap
0.0055
0.0125
0.0087***
0.0100
6,650
Bathroom Tissues
0.0189**
0.0081
-0.0208**
0.0136
56,458
Beer
0.0042***
0.0007
0.0049***
0.0011
187,691
Bottled Juice
0.0199***
0.0070
-0.0346***
0.0084
224,857
Canned Soup
-0.0008
0.0085
-0.0325***
0.0093
233,779
Canned Tuna
-0.0015
0.0058
0.0139**
0.0108
112,629
Cereals
0.0085
0.0065
-0.1025**
0.0145
141,087
Cheese
0.0072**
0.0034
-0.0557***
0.0098
357,679
Cigarettes
0.0009
0.0046
0.0852***
0.0058
24,553
Cookies
0.0091***
0.0019
-0.0347***
0.0080
317,932
Crackers
0.0048
0.0031
-0.0528**
0.0119
115,658
Dish Detergent
0.0258***
0.0062
-0.0356**
0.0155
85,222
Fabric Softener
0.0023
0.0057
0.0146**
0.0110
85,337
Front-End-Candies
-0.0034
0.0033
0.0242**
0.0121
148,200
Frozen Dinners
0.0342***
0.0060
0.0555***
0.0083
52,893
Frozen Entrees
0.0192***
0.0026
-0.0438***
0.0059
345,223
Frozen Juices
0.0131*
0.0067
-0.052**
0.0146
118,582
Grooming Products
0.0112***
0.0033
0.0011***
0.0034
101,944
Laundry Detergents
0.013***
0.0038
0.0001**
0.0106
121,566
Oatmeal
0.0091
0.0116
-0.0569**
0.0218
25,523
Paper Towels
0.0184
0.0171
-0.0751**
0.0184
48,199
Refrigerated Juices
0.0066
0.0078
-0.024**
0.0111
108,965
Shampoos
0.0089***
0.0025
0.0199***
0.0031
88,193
Snack Crackers
0.0035
0.0027
0.0008**
0.0134
176,527
Soap
0.0184**
0.0080
-0.0284***
0.0102
56,725
Soft Drinks
0.0137***
0.0018
-0.0331***
0.0075
243,837
Toothbrushes
0.0089*
0.0046
0.0056***
0.0095
52,185
Toothpastes
0.0012
0.0038
-0.019***
0.0088
100,845
Average
0.0101
0.0056
-0.0164
0.0104
131,496
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change. The dependent
variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less or equal to 10¢, and 0 otherwise.
The main independent variables are the log of average sales volume of product i in store s over the sample period and a dummy for peak
days that equals 1 if it is one of the weeks with the largest number of price changes, so that all the peak weeks account for 50% of all the
price changes. The regressions also include the following independent variables: the products’ average price, percentage changes in the
wholesale price, a dummy for sale and bounce-back prices, a dummy for 9-ending prices that equals 1 if the right-most digit is 9, as well
as fixed effects for years, months, stores, and products. We estimate separate regressions for each product category, clustering the errors
by product. * p < 10%, ** p < 5%, *** p < 1%
119
Table P4. Bonomo regressions – focusing on regular prices
Category
Sales Volume
Peak days
No. of
Observations
Coefficient
Std.
Coefficient
Std.
Analgesics
0.014*
0.0080
-0.0266
0.0189
24,729
Bath Soap
-0.0272
0.0253
0.0082
0.0192
1,466
Bathroom Tissues
0.037***
0.0094
-0.0364**
0.0182
19,285
Beer
0.0182***
0.0055
-0.0087*
0.0130
12,080
Bottled Juice
0.035***
0.0089
-0.0213
0.0164
60,015
Canned Soup
0.0133**
0.0071
0.0095
0.0117
95,310
Canned Tuna
0.0132
0.0083
-0.0034
0.0202
31,922
Cereals
0.0275***
0.0071
-0.1595***
0.0209
72,789
Cheese
0.0139***
0.0046
-0.0516***
0.0156
92,758
Cigarettes
-0.0006
0.0053
0.0759***
0.0065
20,692
Cookies
0.0088**
0.0037
-0.0454***
0.0163
66,087
Crackers
0.0174***
0.0065
-0.1153***
0.0253
24,771
Dish Detergent
0.0306***
0.0061
-0.1054***
0.0305
26,735
Fabric Softener
0.0228***
0.0078
0.01
0.0226
27,488
Front-End-Candies
0.0018
0.0030
-0.0045
0.0130
77,323
Frozen Dinners
0.0698***
0.0103
0.0557***
0.0176
12,287
Frozen Entrees
0.0239***
0.0039
-0.0004
0.0074
117,044
Frozen Juices
0.0229***
0.0086
-0.0508**
0.0234
40,517
Grooming Products
0.0158
0.0110
0.0094
0.0107
22,102
Laundry Detergents
0.0175***
0.0058
0.0001
0.0194
42,121
Oatmeal
0.0597***
0.0113
-0.0119
0.0269
13,605
Paper Towels
0.0312*
0.0158
-0.0668**
0.0278
9,243
Refrigerated Juices
0.0259**
0.0123
-0.0163
0.0318
23,705
Shampoos
0.0225***
0.0080
0.0082
0.0096
16,099
Snack Crackers
0.0173***
0.0053
-0.0685**
0.0282
38,123
Soap
0.0539***
0.0119
-0.0742***
0.0210
16,882
Soft Drinks
0.0059*
0.0033
0.0345***
0.0119
49,989
Toothbrushes
0.0195*
0.0102
-0.0113
0.0270
13,695
Toothpastes
0.0058
0.0082
-0.0169
0.0195
28,039
Average
0.0213
0.0084
-0.0236
0.0190
37,824
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change. The dependent
variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less or equal to 10¢, and 0 otherwise.
The main independent variables are the log of average sales volume of product i in store s over the sample period and a dummy for peak
days that equals 1 if it is one of the weeks with the largest number of price changes, so that all the peak weeks account for 50% of all the
price changes. The regressions also include the following independent variables: the products’ average price, percentage changes in the
wholesale price, a dummy for 9-ending prices that equals 1 if the right-most digit is 9, as well as fixed effects for years, months, stores,
and products. We exclude observations on sales and bounce back prices. We estimate separate regressions for each product category,
clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
120
Appendix Q. Estimation using only data on products that are sold in single units
In the paper, we study the correlation between the sales volume and the likelihood of
small price changes. There, we define a unit sold the way it is defined by the retailer. I.e.,
a 6-pack of beer is counted as one unit. However, this might bias the results if products
that are sold in packages have different properties than products that are sold in single
units. We therefore repeat our estimation, after excluding observations on products that
are sold in packages.
We therefore estimate:
(Q1)
where small price change is a dummy that equals 1 if a price change of product i in store
s in week t is less or equal to 10¢, and 0 otherwise. As we do in the paper, we use
observations on price changes only if we observe the price in both weeks t and t + 1 and
the post change price remained unchanged for at least 2 weeks.
The average sales volume is the average sales volume of product i in store s over the
sample period. By taking the average over a long period, we obtain an estimate of the
expected sales volume that does not depend on transitory shocks or sales. X is a matrix of
other control variables. Month and year are fixed effects for the month (to control for
seasonality) and the year of the price change. To control for the differences across stores
and products,
and
are fixed effects for stores and products, respectively, while u is
an i.i.d error term.
Table Q1 reports the coefficient estimates of the key variable, average sales volume,
for each product category. Column 1 reports the results of baseline regressions that
exclude the X matrix. I.e, the regressions include only the average sales volume and fixed
effects for months, years, stores, and products.
We find that in all 29 product categories, the coefficients are positive and statistically
significant. The estimated effect is economically significant. The average coefficient is
0.027, suggesting that an increase of 1% in the sales volume is associated with an
increase of 2.7 percentage points in the likelihood that a price change will be small.
121
In column 2, we add the matrix X which includes the following control variables: the
log of the average price to control for the price level effect on the size of price changes,
the percentage change in the wholesale price, and control for sale- and bounce-back
prices, all as defined above. The estimation results are similar to what we report in
column 1. The coefficients of the average sales volume are positive and statistically
significant in 28 categories, and marginally significant in 1 more. The average coefficient
is 0.020. Thus, even after including the controls, we still find that increasing the average
sales volume by 1% is associated with an increase of 2.0 percentage points in the
likelihood of a small price change.
In column 3, we add a dummy for 9-ending prices as an additional control because
when the pre-change price is 9-ending, price changes tend to be larger than when the pre-
change price ends in other digits (Levy et al. 2020). Thus, if products with high sales
volume tend to have non-9-ending prices, then it might lead to high sales volume
products’ prices changing by small amounts.
However, adding this dummy does not change the main result appreciably. All 29
coefficients remain positive. 28 are statistically significant, and 1 more is marginally
significant. Controlling for 9-ending prices, increasing the average sales volume by 1% is
associated with a 2.0 percentage points increase in the likelihood of a small price change,
on average.
In column 4, we focus on regular prices by excluding sale- and bounce-back prices.
We do this for two reasons. First, sale- and bounce-back prices tend to be large, and
therefore, we need to account for them properly. Second, it is often argued that changes
in sale prices have a smaller effect on inflation than changes in regular prices (Nakamura
and Steinsson 2008, Midrigan 2011, Anderson et al. 2017, Ray et al. 2023).
We find that when we exclude sale prices, all the coefficients remain positive. 28 are
statistically significant, and 1 more is marginally significant. The average coefficient is
0.041, implying that for regular prices, an increase of 1% in the average sales volume is
associated with an increase of 4.1 percentage points in the likelihood of a small price
change.
122
Table Q1. Category-level regressions of small price changes and sales volume excluding
products sold in packages
Category
(1)
(2)
(3)
(4)
Analgesics
Coefficient
(Std.)
0.0262***
(0.0034)
0.019***
(0.0032)
0.0113***
(0.0021)
0.0188***
(0.0031)
Observations
144,461
144,461
144,461
144,461
Bath Soap
Coefficient
(Std.)
0.0293***
(0.008)
0.0277***
(0.0082)
0.0174***
(0.0046)
0.0285***
(0.0081)
Observations
15,295
15,295
15,295
15,295
Bathroom
Tissues
Coefficient
(Std.)
0.0328***
(0.0077)
0.008*
(0.0072)
0.0137***
(0.0056)
0.0083*
(0.0072)
Observations
140,505
140,505
149,441
140,505
Beer
Coefficient
(Std.)
0.013***
(0.0012)
0.0147***
(0.0012)
0.0114***
(0.0008)
0.0147***
(0.0012)
Observations
290,591
290,591
290,620
290,591
Bottled Juice
Coefficient
(Std.)
0.0376***
(0.0051)
0.0271***
(0.0044)
0.017***
(0.0042)
0.026***
(0.0044)
Observations
471,256
471,256
496,557
471,256
Canned Soup
Coefficient
(Std.)
0.0167***
(0.0056)
0.0077***
(0.0051)
0.0121***
(0.0043)
0.0098**
(0.0049)
Observations
461,989
461,989
495,543
461,989
Canned Tuna
Coefficient
(Std.)
0.0249***
(0.0055)
0.0146***
(0.0047)
0.0124***
(0.0038)
0.0142***
(0.0046)
Observations
206,937
206,937
213,043
206,937
Cereals
Coefficient
(Std.)
0.021***
(0.0037)
0.0158**
(0.0034)
0.0133***
(0.003)
0.0157***
(0.0035)
Observations
354,887
354,887
357,120
354,887
Cheese
Coefficient
(Std.)
0.021***
(0.0029)
0.012***
(0.0025)
0.0084***
(0.0023)
0.0118***
(0.0025)
Observations
780,089
780,089
796,150
780,089
Cigarettes
Coefficient
(Std.)
0.0084**
(0.0046)
0.0073**
(0.0045)
0.0095**
(0.0028)
0.0074**
(0.0044)
Observations
36,157
36,157
36,157
36,157
Cookies
Coefficient
(Std.)
0.0276***
(0.0018)
0.0225***
(0.0017)
0.018***
(0.0014)
0.0227***
(0.0017)
Observations
668,546
668,546
688,761
668,546
Crackers
Coefficient
(Std.)
0.0387***
(0.0031)
0.0301***
(0.0027)
0.0232***
(0.0022)
0.0306***
(0.0027)
Observations
239,253
239,253
245,185
239,253
Dish
Detergent
Coefficient
(Std.)
0.0394***
(0.0044)
0.0279***
(0.0036)
0.0212***
(0.0031)
0.0278***
(0.0035)
Observations
188,737
188,737
189,633
188,737
Fabric
Softener
Coefficient
(Std.)
0.0246***
(0.0048)
0.0118***
(0.0044)
0.0089***
(0.0034)
0.0121***
(0.0043)
Observations
178,724
178,724
181,056
178,724
Front-End-
Candies
Coefficient
(Std.)
0.0103***
(0.004)
0.0161***
(0.0041)
0.0048***
(0.0026)
0.0163***
(0.0041)
Observations
192,037
192,037
278,853
192,037
Frozen
Dinners
Coefficient
(Std.)
0.0478***
(0.0035)
0.0385***
(0.0031)
0.0308***
(0.0023)
0.0411***
(0.0032)
Observations
187,022
187,022
203,191
187,022
123
Table Q1. (Cont.)
Category
(1)
(2)
(3)
(4)
Frozen Entrees
Coefficient
(Std.)
0.0288***
(0.0024)
0.0281***
(0.002)
0.0193***
(0.0015)
0.0289***
(0.002)
Observations
694,903
694,903
864,832
694,903
Frozen Juices
Coefficient
(Std.)
0.0289***
(0.0049)
0.0223***
(0.0044)
0.0162***
(0.0035)
0.0227***
(0.0043)
Observations
286,846
286,846
308,817
286,846
Grooming
Products
Coefficient
(Std.)
0.0186***
(0.0023)
0.0208***
(0.0024)
0.0135***
(0.0016)
0.021***
(0.0024)
Observations
269,513
269,513
269,873
269,513
Laundry
Detergents
Coefficient
(Std.)
0.0198***
(0.0032)
0.0094***
(0.0028)
0.0082***
(0.0023)
0.0099***
(0.0028)
Observations
270,780
270,780
272,765
270,780
Oatmeal
Coefficient
(Std.)
0.0283***
(0.0081)
0.0151***
(0.0067)
0.0129***
(0.0058)
0.0153***
(0.0067)
Observations
79,488
79,488
79,983
79,488
Paper Towels
Coefficient
(Std.)
0.0479***
(0.0114)
0.026***
(0.0099)
0.0254***
(0.0083)
0.0264***
(0.01)
Observations
111,012
111,012
116,204
111,012
Refrigerated
Juices
Coefficient
(Std.)
0.0357***
(0.0047)
0.0209***
(0.0039)
0.0177***
(0.0033)
0.0208***
(0.0039)
Observations
304,028
304,028
306,865
304,028
Shampoos
Coefficient
(Std.)
0.0164***
(0.0015)
0.0202***
(0.0016)
0.0119***
(0.001)
0.0202***
(0.0016)
Observations
260,918
260,918
261,778
260,918
Snack
Crackers
Coefficient
(Std.)
0.033***
(0.0032)
0.0284***
(0.003)
0.0236***
(0.0026)
0.0285***
(0.003)
Observations
390,331
390,331
398,665
390,331
Soaps
Coefficient
(Std.)
0.0373***
(0.0055)
0.0224***
(0.005)
0.0162***
(0.0037)
0.0234***
(0.0049)
Observations
151,326
151,326
152,379
151,326
Soft Drinks
Coefficient
(Std.)
0.026***
(0.0015)
0.0243***
(0.0014)
0.0099***
(0.0018)
0.0238***
(0.0013)
Observations
1,247,126
1,247,126
1,350,618
1,247,126
Toothbrushes
Coefficient
(Std.)
0.0212***
(0.0029)
0.0204***
(0.0029)
0.0137***
(0.0018)
0.0198***
(0.0029)
Observations
121,951
121,951
125,380
121,951
Toothpastes
Coefficient
(Std.)
0.0124***
(0.0026)
0.0113***
(0.0022)
0.0088***
(0.0016)
0.0113***
(0.0022)
Observations
263,971
263,971
264,317
263,971
Average coefficients
0.0267
0.0197
0.0199
0.0415
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change.
The dependent variable is “small price change,” which equals 1 if a price change of product i in store s at time t is less
or equal to 10¢, and 0 otherwise. The main independent variable is the log of average sales volume of product i in store
s over the sample period. Column 1 reports the results of the baseline regression that includes only the log of average
sales volume and the fixed effects for months, years, stores, and products. In column 2, we add the following controls:
the log of the average price, the log of the absolute change in the wholesale price, and a control for sale- and bounce-
back prices, which we identify using a sales filter algorithm. In column 3, we add a dummy for 9-ending prices as an
additional control. In column 4, we focus on regular prices by excluding the sale- and bounce-back prices. We estimate
separate regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
124
Appendix R. Storable vs. non-storable products
It’s possible that retailers have different strategies for storable vs. non-storable
products. To test whether this has an effect on the correlation between small price
changes and sales volumes, we estimate the following regression, using pooled data from
all product categories:
(R1)
where small price change is a dummy that equals 1 if a price change of product i in store
s in week t is less or equal to 10¢, and 0 otherwise. As we do in the paper, we use
observations on price changes only if we observe the price in both weeks t and t + 1 and
the post change price remained unchanged for at least 2 weeks. The average sales volume
is the average sales volume of product i in store s over the sample period.
6
By taking the
average over a long period, we obtain an estimate of the expected sales volume that does
not depend on transitory shocks or sales. X is a matrix of other control variables. Month
and year are fixed effects for the month (to control for seasonality) and the year of the
price change. To control for the differences across stores and products, ,
and
are
fixed effects for categories, stores and products, respectively, while u is an i.i.d error
term. is a dummy for products that have a high cost of storage. It equals 1
if a product belongs to either of the cheese, frozen dinners, frozen entrees, frozen juices,
or refrigerated juices categories.
Table R1 reports the coefficient estimates of the key variables, average sales volume,
and the interaction between the average sales volume and the dummy for non-storable
products. Column 1 reports the results of baseline regressions that exclude the matrix X.
6
In calculating the average sales volume, we need to account for missing observations, because a missing observation
in week t implies that the product was either out of stock or had 0 sales on that week. Thus, averaging over the
available observations can lead to an upward bias for products that are sold in small numbers. Therefore, for each
product in each store, we calculate the average by first determining the total number of units sold over all available
observations. We then identify the first and last week for which we have observations, and calculate the average for
each product-store as
. The resulting figure is smaller than we would obtain if we averaged over all
available observations (which would not include obsservations on weeks with 0 sales).
125
I.e, the regressions include only the average sales volume, the interaction between the
average sales volume and the dummy for non-storable products, the dummy for non-
storable products, and fixed effects for months, years, stores, categories, and products.
We find that the coefficient of the sales volume is positive and statistically
significant. Its value is similar to the value we report in the paper, 0.025. The value of the
coefficient of the interaction between the sales volume and the dummy for non-storable
products is small, 0.004, positive and statistically significant. Thus, the results suggests
that the correlation between sales volumes and small price changes might be slightly
stronger for products that are harder to store than for other products.
In column 2, we add the matrix X which includes the following control variables: the
log of the average price to control for the price level effect on the size of price changes,
the percentage change in the wholesale price, and control for sale- and bounce-back
prices, all as defined above. We find that the coefficient of the interaction term is now
negative, but it is not statistically significant.
In column 3, we add a dummy for 9-ending prices as an additional control because
when the pre-change price is 9-ending, price changes tend to be larger than when the pre-
change price ends in other digits (Levy et al. 2020). Thus, if products with high sales
volume tend to have non-9-ending prices, then it might lead to high sales volume
products’ prices changing by small amounts. According to our estimates, the coefficient
of the interaction term remains negative, and it is not statistically significant.
In column 4, we focus on regular prices by excluding sale- and bounce-back prices.
We do this for two reasons. First, sale- and bounce-back prices tend to be large, and
therefore, we need to account for them properly. Second, it is often argued that changes
in sale prices have a smaller effect on inflation than changes in regular prices (Nakamura
and Steinsson 2008, Midrigan 2011, Anderson et al. 2017, Ray et al. 2023).
We find that when we exclude sale prices, the results remain similar to our findings in
columns 2 and 3. The coefficient of the interaction term remains small, negative and
statistically insignificant. We therefore conclude that the correlation between the
likelihood of a small price change and the sales volumes is similar across storable and
less storable products.
126
Table R1. Pooled regressions of small price changes and sales volume, with
controls for non-durable products
(1)
(2)
(3)
(4)
Average sales volume
0.025***
(0.001)
0.018***
(0.001)
0.018***
(0.001)
0.018***
(0.001)
Average sales volume
× non-storable
0.004**
(0.002)
−0.003
(0.002)
−0.003
(0.002)
−0.003
(0.002)
Observations
9,553,542
9,553,542
9,553,542
2,328,405
Notes: The dependent variable is “small price change,” which equals 1 if a price change of product i in store
s at time t is less or equal to 10¢, and 0 otherwise. The main independent variable is the log of the average
sales volume of product i in store s over the sample period. Non-storable is a dummy for products that are
costly to store. Column 1 reports the results of baseline regression that includes only the average sales
volume and the fixed effects for months, years, stores, and products. In column 2, we add the following
controls: the log of the average price, the log of the absolute change in the wholesale price, and control for
sale- and bounce-back prices, which we identify using a sales filter algorithm. In column 3, we add a dummy
for 9-ending prices as an additional control. In column 4, we focus on regular prices by excluding the sale-
and bounce-back prices. All regressions also include a dummy for non-storable products, and fixed effects
for categories, stores, products, years, and months. We estimate separate regressions for each product
category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
127
Appendix S. The correlation between the sales volume and the likelihood of price
increases vs. decreases
Our model implies that the correlation between the sales volume and the likelihood of
a small price change is symmetric. Products with high sales volumes should be more likely
to both increase and decrease than products with lower sales volumes. However, empirical
evidence suggests that this might not be the case (Peltzman, 2000). For example, if
shoppers are not attentive to small price changes (Chen et al., 2008, Chakraborty et al.,
2015), then retailers may gain from small price increases and lose from small price
decreases.
Therefore, in Tables S1–S4, we present the results of the category-level regression
estimations. The regressions we estimate are of the following form:
(S1)
where small price increase (decrease) is a dummy that equals 1 if a price change of
product i in store s at time t is less or equal to 10¢, and 0 otherwise. The average sales
volume is the average sales volume of product i in store s over the sample period. The
average revenue is the average revenue of product i in store s over the sample period. X
is a matrix of other control variables. Month and year are fixed effects for the month and
the year of the price change.
and
are fixed effects for stores and products,
respectively, and u is an i.i.d error term. We estimate a separate regression for each
product category, clustering the errors by product. As we do in the paper, we use
observations on price changes only if we observe the price in both weeks t and t+1 and
the post-change price remained unchanged for at least 2 weeks.
Table S1 reports the results of baseline regressions that exclude the matrix X. I.e, the
regressions include only the average sales volume and fixed effects for months, years,
stores, and products.
For price increases, we find that in all 29 product categories, the coefficients are
positive and statistically significant. For price decreases, 27 of the coefficients are
positive, and 20 of them are statistically significant. Two more are marginally significant.
128
It therefore seems that the correlation between price increases and the likelihood of small
price changes is stronger than the correlation between price decreases and the likelihood
of small price changes. This is also corroborated by the size of the coefficients. In 21
categories, the coefficients of price increases are larger than the coefficients of price
decreases, yielding an average coefficient of 0.0195 for price increases and 0.0146 for
price decreases.
In Table S2, we add the X matrix which includes the following control variables: the
log of the average price to control for the price level effect on the size of price changes,
the percentage change in the wholesale price, and control for sale- and bounce-back
prices, all as defined above. The results are similar to what we report above. When we
focus on price increases, we find that all the coefficients are positive, and that 28 of them
are statistically significant. When we focus on price decreases, we find that 27 of the
coefficients are positive, 19 of them are statistically significant, and 2 more are
marginally significant. Again, the average coefficient of price increases, 0.0162, is larger
than the average coefficients of price decreases, 0.0127.
In Table S3, we add a dummy for 9-ending prices as an additional control because
when the pre-change price is 9-ending, price changes tend to be larger than when the pre-
change price ends in other digits (Levy et al. 2020). Thus, if products with high sales
volume tend to have non-9-ending prices, then it might lead to high sales volume
products’ prices changing by small amounts. The results remain almost unchanged
relative to the figures presented in Table S2.
In Table S4, we focus on regular prices by excluding sale- and bounce-back prices.
We do this for two reasons. First, sale- and bounce-back prices tend to be large, and
therefore, we need to account for them properly. Second, it is often argued that changes
in sale prices have a smaller effect on inflation than changes in regular prices (Nakamura
and Steinsson 2008, Midrigan 2011, Anderson et al. 2017, Ray et al. 2023).
We find that when we exclude sale prices, 29 of the coefficients of the price increase
regressions are positive, and all of them are statistically significant. In the regressions of
price decreases, 26 of the coefficients are positive and 20 of them are statistically
significant. 4 more are marginally significant. The average coefficient of the price
increase regressions is 0.0303, again higher than the average coefficient of the price
129
decrease regressions, 0.0213.
We conclude that the correlation is stronger for price increases than for price
decreases. Therefore, although our model suggests a symmetric correlation, it seems that
there are other forces at play as well. One possibility is consumer inattention, which
makes small price increases more profitable than small price decreases, as in Chen et al.
(2008).
130
Table S1. Category-level regressions of small price changes and sales volume, price
increases vs. price decreases
Notes: The table reports the results of category-level fixed effect regressions of the probability of a small price change. We
estimate separate regressions for price increases and for price decreases. The dependent variable is “small price change,” which
equals 1 if a price change of product i in store s at time t is less or equal to 10¢, and 0 otherwise. The main independent variables
are the log of average sales volume of product i in store s over the sample period and the log of the average revenue of product
i in store s over the sample period. The regressions also includes fixed effects for years, months, stores, and products. We
estimate separate regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p < 1%
Category
Price Increase
Observations
Price Decrease
Coefficient
Std.
Obs.
Coefficient
Std.
Obs.
Analgesics
0.0107***
0.0378
93,254
0.021***
0.0034
51,207
Bath Soap
0.0211***
0.0870
9,877
0.0047
0.0058
5,418
Bathroom Tissues
0.0284***
0.0498
96,660
0.0156*
0.0087
52,781
Beer
0.013***
0.0273
128,309
0.0049***
0.0007
162,311
Bottled Juice
0.023***
0.0800
298,844
0.0173***
0.0061
197,713
Canned Soup
0.019***
0.0390
334,515
0.0015
0.0066
161,028
Canned Tuna
0.0164***
0.0569
110,869
0.0139***
0.0044
102,174
Cereals
0.02***
0.0326
262,840
0.0077
0.0049
94,280
Cheese
0.0176***
0.0842
506,336
0.0132***
0.0032
289,814
Cigarettes
0.0128***
0.0386
27,370
-0.0024
0.0035
8,787
Cookies
0.0234***
0.0166
440,768
0.0178***
0.0019
247,993
Crackers
0.032***
0.0804
152,814
0.0267***
0.0035
92,371
Dish Detergent
0.0304***
0.0928
120,854
0.0307***
0.0047
68,779
Fabric Softener
0.0123***
0.1206
110,126
0.0146***
0.005
70,930
Front-End-Candies
0.0073**
0.0199
168,056
-0.0145***
0.0036
110,797
Frozen Dinners
0.0262***
0.0252
142,131
0.0523***
0.0044
61,060
Frozen Entrees
0.0178***
0.0097
593,786
0.0242***
0.0023
271,046
Frozen Juices
0.0196***
0.0361
201,311
0.0256***
0.0059
107,506
Grooming Products
0.0084***
0.0254
177,107
0.0117***
0.0022
92,766
Laundry Detergents
0.0102***
0.0369
166,698
0.0164***
0.0031
106,067
Oatmeal
0.0246***
0.0159
55,650
0.0185**
0.0086
24,333
Paper Towels
0.0362***
0.1112
71,451
0.0106
0.0095
44,753
Refrigerated Juices
0.0348***
0.0371
195,097
0.0161***
0.0047
111,768
Shampoos
0.0096***
0.0136
174,176
0.0068***
0.0015
87,602
Snack Crackers
0.0292***
0.0661
253,228
0.0252***
0.0037
145,437
Soap
0.0236***
0.0198
94,977
0.0218***
0.0061
57,402
Soft Drinks
0.0139***
0.1117
1,037,125
0.0048*
0.0028
313,493
Toothbrushes
0.0144***
0.0322
83,428
0.0105***
0.0028
41,952
Toothpastes
0.0091***
0.0354
189,477
0.0069
0.0042
74,840
Average
0.0195
0.0035
217,143
0.0146
0.0044
112,290
131
Table S2. Category-level regressions of small price changes and sales volume, price increases
vs. price decreases, with extra controls
The table reports the results of category-level fixed effect regressions of the probability of a small price change. We estimate
separate regressions for price increases and for price decreases. The dependent variable is “small price change,” which equals
1 if a price change of product i in store s at time t is less or equal to 10¢, and 0 otherwise. The main independent variables are
the log of average sales volume of product i in store s over the sample period and the log of the average revenue of product i
in store s over the sample period. The regressions also include the following independent variables: percentage changes in the
wholesale price, a dummy for sale and bounce-back prices, as well as fixed effects for years, months, stores, and products.
We estimate separate regressions for each product category, clustering the errors by product. * p < 10%, ** p < 5%, *** p <
1%
Category
Price Increase
Observations
Price Decrease
Coefficient
Std.
Obs.
Coefficient
Std.
Obs.
Analgesics
0.0097***
0.0024
93,254
0.0159***
0.0031
51,207
Bath Soap
0.0201***
0.0064
9,877
0.0042
0.006
5,418
Bathroom Tissues
0.0086
0.0058
96,660
0.0124
0.0079
52,781
Beer
0.0167***
0.0014
128,309
0.0077***
0.0007
162,311
Bottled Juice
0.0175***
0.0037
298,844
0.0172***
0.0055
197,713
Canned Soup
0.016***
0.004
334,515
0.0023
0.0063
161,028
Canned Tuna
0.0125***
0.0043
110,869
0.0125***
0.0042
102,174
Cereals
0.0164***
0.0028
262,840
0.0053
0.0048
94,280
Cheese
0.0102***
0.0022
506,336
0.0082***
0.003
289,814
Cigarettes
0.0131***
0.0028
27,370
-0.0013
0.0037
8,787
Cookies
0.0199***
0.0016
440,768
0.0178***
0.0019
247,993
Crackers
0.0239***
0.0025
152,814
0.0237***
0.0034
92,371
Dish Detergent
0.0225***
0.0033
120,854
0.0245***
0.0044
68,779
Fabric Softener
0.0094***
0.0034
110,126
0.0096**
0.0047
70,930
Front-End-Candies
0.0124***
0.0032
168,056
-0.0082***
0.0027
110,797
Frozen Dinners
0.0231***
0.0024
142,131
0.0456***
0.004
61,060
Frozen Entrees
0.0193***
0.0015
593,786
0.023***
0.0022
271,046
Frozen Juices
0.0142***
0.0036
201,311
0.0232***
0.0053
107,506
Grooming Products
0.0117***
0.0017
177,107
0.0149***
0.0022
92,766
Laundry Detergents
0.0068***
0.0023
166,698
0.0102***
0.0031
106,067
Oatmeal
0.0193***
0.0062
55,650
0.007
0.0088
24,333
Paper Towels
0.0332***
0.0083
71,451
0.0116
0.0102
44,753
Refrigerated Juices
0.0221***
0.0034
195,097
0.0105**
0.0043
111,768
Shampoos
0.0128***
0.0011
174,176
0.0086***
0.0015
87,602
Snack Crackers
0.0244***
0.0025
253,228
0.0247***
0.0036
145,437
Soap
0.016***
0.0038
94,977
0.0146***
0.0057
57,402
Soft Drinks
0.0126***
0.0017
1,037,125
0.0052*
0.0027
313,493
Toothbrushes
0.0154***
0.0021
83,428
0.0119***
0.0028
41,952
Toothpastes
0.0107***
0.0019
189,477
0.0058*
0.003
74,840
Average
0.0162
0.0032
217,143
0.0127
0.0042
112,290
132
Table S3. Category-level regressions of small price changes and sales volume, price
increases vs. price decreases, with extra controls and a dummy for 9-ending prices
The table reports the results of category-level fixed effect regressions of the probability of a small price change. We estimate
separate regressions for price increases and for price decreases. The dependent variable is “small price change,” which equals
1 if a price change of product i in store s at time t is less or equal to 10¢, and 0 otherwise. The main independent variables are
the log of average sales volume of product i in store s over the sample period and the log of the average revenue of product i in
store s over the sample period. The regressions also include the following independent variables: percentage changes in the
wholesale price, a dummy for sale and bounce-back prices, and a dummy for 9-ending prices, as well as fixed effects for years,
months, stores, and products. We estimate separate regressions for each product category, clustering the errors by product. * p
< 10%, ** p < 5%, *** p < 1%
Category
Price Increase
Observations
Price Decrease
Coefficient
Std.
Obs.
Coefficient
Std.
Obs.
Analgesics
0.0097***
0.0024
93,254
0.0155***
0.0031
51,207
Bath Soap
0.0221***
0.0064
9,877
0.0044
0.0061
5,418
Bathroom Tissues
0.0091
0.0058
96,660
0.0119
0.0079
52,781
Beer
0.0167***
0.0014
128,309
0.0077***
0.0008
162,311
Bottled Juice
0.0175***
0.0037
298,844
0.0155***
0.0056
197,713
Canned Soup
0.0182***
0.0039
334,515
0.0039
0.0062
161,028
Canned Tuna
0.0123***
0.0043
110,869
0.0125***
0.0042
102,174
Cereals
0.0164***
0.0028
262,840
0.0049
0.0048
94,280
Cheese
0.01***
0.0022
506,336
0.0074***
0.003
289,814
Cigarettes
0.0129***
0.0028
27,370
-0.0011
0.0038
8,787
Cookies
0.02***
0.0016
440,768
0.0174***
0.0019
247,993
Crackers
0.0241***
0.0025
152,814
0.0232***
0.0034
92,371
Dish Detergent
0.0227***
0.0033
120,854
0.0236***
0.0042
68,779
Fabric Softener
0.0094***
0.0034
110,126
0.0098**
0.0047
70,930
Front-End-Candies
0.0143***
0.0032
168,056
-0.0076***
0.0026
110,797
Frozen Dinners
0.0244***
0.0023
142,131
0.0453***
0.004
61,060
Frozen Entrees
0.0193***
0.0015
593,786
0.0235***
0.0022
271,046
Frozen Juices
0.015***
0.0036
201,311
0.0226***
0.0052
107,506
Grooming Products
0.0118***
0.0017
177,107
0.0144***
0.0022
92,766
Laundry Detergents
0.0071***
0.0023
166,698
0.0102***
0.0031
106,067
Oatmeal
0.0195***
0.0063
55,650
0.0052
0.0089
24,333
Paper Towels
0.0336***
0.0086
71,451
0.0114
0.0099
44,753
Refrigerated Juices
0.0221***
0.0034
195,097
0.0094**
0.0044
111,768
Shampoos
0.0128***
0.0011
174,176
0.0087***
0.0015
87,602
Snack Crackers
0.0244***
0.0026
253,228
0.0246***
0.0036
145,437
Soap
0.016***
0.0038
94,977
0.0172***
0.0055
57,402
Soft Drinks
0.0125***
0.0016
1,037,125
0.0047*
0.0025
313,493
Toothbrushes
0.0154***
0.0021
83,428
0.0104***
0.0028
41,952
Toothpastes
0.0107***
0.0019
189,477
0.0057*
0.003
74,840
Average
0.0166
0.0032
217,143
0.0125
0.0042
112,290
133
Table S4. Category-level regressions of small price changes and sales volume, price increases
vs. price decreases, focusing on regular prices
The table reports the results of category-level fixed effect regressions of the probability of a small price change. We estimate
separate regressions for price increases and for price decreases. The dependent variable is “small price change,” which equals
1 if a price change of product i in store s at time t is less or equal to 10¢, and 0 otherwise. The main independent variables are
the log of average sales volume of product i in store s over the sample period and the log of the average revenue of product i
in store s over the sample period. The regressions also include the following independent variables: percentage changes in the
wholesale price, a dummy for sale and bounce-back prices, and a dummy for 9-ending prices, as well as fixed effects for
years, months, stores, and products. We estimate separate regressions for each product category, clustering the errors by
product. * p < 10%, ** p < 5%, *** p < 1%
Category
Price Increase
Observations
Price Decrease
Coefficient
Std.
Obs.
Coefficient
Std.
Obs.
Analgesics
0.0157***
0.0047
33,833
0.0346***
0.0087
11,117
Bath Soap
0.052***
0.0143
2,610
0.0209
0.0263
598
Bathroom Tissues
0.0303***
0.0105
27,822
0.0188*
0.0096
19,219
Beer
0.0523***
0.0049
16,369
0.0311***
0.0059
10,979
Bottled Juice
0.0202***
0.006
84,037
0.0219**
0.0087
49,677
Canned Soup
0.0188***
0.0044
121,223
-0.0004
0.007
55,012
Canned Tuna
0.018***
0.0059
35,488
0.0218***
0.006
28,673
Cereals
0.0174***
0.0043
112,141
0.0159***
0.0062
43,226
Cheese
0.0163***
0.0031
145,646
0.0022
0.0048
79,243
Cigarettes
0.0123***
0.0031
24,297
-0.0053
0.0042
5,965
Cookies
0.0371***
0.0033
97,877
0.0227***
0.0036
34,611
Crackers
0.0381***
0.0056
35,793
0.0266***
0.0081
14,236
Dish Detergent
0.0285***
0.0047
29,978
0.0256***
0.0056
23,311
Fabric Softener
0.016***
0.0057
31,744
0.035***
0.0064
24,490
Front-End-Candies
0.0126***
0.0028
65,667
-0.0001
0.0027
45,968
Frozen Dinners
0.0609***
0.0067
19,262
0.06***
0.0063
18,265
Frozen Entrees
0.0411***
0.0036
117,948
0.0266***
0.0034
95,597
Frozen Juices
0.025***
0.0061
50,141
0.027***
0.0068
37,778
Grooming Products
0.0268***
0.0043
37,589
0.0169*
0.0094
14,230
Laundry Detergents
0.0128***
0.0044
47,061
0.0193***
0.0048
38,123
Oatmeal
0.0297***
0.0107
22,934
0.0258***
0.0116
13,109
Paper Towels
0.0368***
0.0096
16,360
0.0219*
0.0112
12,920
Refrigerated Juices
0.0329***
0.0056
44,566
0.0121*
0.0067
27,465
Shampoos
0.0272***
0.0035
29,135
0.0171***
0.0065
11,861
Snack Crackers
0.0445***
0.0046
55,142
0.0231***
0.0076
23,439
Soap
0.038***
0.0064
28,658
0.0174**
0.0084
18,171
Soft Drinks
0.0539***
0.0033
86,187
0.0112***
0.0035
69,817
Toothbrushes
0.0351***
0.0056
18,109
0.0349***
0.0082
6,846
Toothpastes
0.0277***
0.0045
41,918
0.0341***
0.0083
14,924
Average
0.0303
0.0056
51,018
0.0213
0.0075
29,271
134
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