Alexander Coppock

• PhD Student at Columbia University

In the task of assessing how sudden, significant events causally affect public opinion, political pollsters often ask respondents how the event affected their attitudes and beliefs. We study the case of former President Donald Trump’s federal indictment for allegedly mishandling classified documents using two methods of retrospective causal inferen...

Political campaigns increasingly conduct experiments to learn how to persuade voters. Little research has considered the implications of this trend for elections or democracy. To probe these implications, we analyze a unique archive of 146 advertising experiments conducted by US campaigns in 2018 and 2020 using the platform Swayable. This archive i...

In the difficult task of assessing how sudden, significant events causally affect public opinion, political pollsters often ask respondents how the event affected their attitudes and beliefs. We study the case of former President Donald Trump's federal indictment for allegedly mishandling classified documents using two methods of retrospective caus...

In the final two months of the 2020 US election, we conducted eight panel experiments to evaluate the immediate and medium-term effects of misinformation and factual corrections. Our results corroborate four sets of existing findings: fact-checks reliably improve factual accuracy, while misinformation degrades it; effects of fact-checks on belief a...

We present the results of a large, US$8.9 million campaign-wide field experiment, conducted among 2 million moderate- and low-information persuadable voters in five battleground states during the 2020 US presidential election. Treatment group participants were exposed to an 8-month-long advertising programme delivered via social media, designed to...

Despite the increasing sums devoted to online political advertising, our understanding of the persuasive effects of such advertising is limited. We report the results of a ZIP code level randomized field experiment conducted over Facebook and Instagram during the 2018 U.S. midterm elections in Florida. The ads, produced by a Democratic-leaning poli...

We propose a framework for meta‐analysis of qualitative causal inferences. We integrate qualitative counterfactual inquiry with an approach from the quantitative causal inference literature called extreme value bounds. Qualitative counterfactual analysis uses the observed outcome and auxiliary information to infer what would have happened had the t...

The COVID-19 pandemic imposed new constraints on empirical research, and online data collection by social scientists increased. Generalizing from experiments conducted during this period of persistent crisis may be challenging due to changes in how participants respond to treatments or the composition of online samples. We investigate the generaliz...

Computational reproducibility, or the ability to reproduce analytic results of a scientific study on the basis of publicly available code and data, is a shared goal of many researchers, journals, and scientific communities. Researchers in many disciplines including political science have made strides toward realizing that goal. A new challenge, how...

Surveys often ask respondents how information or events changed their attitudes. Does [information X] make you more or less supportive of [policy Y]? Does [scandal X] make you more or less likely to vote for [politician Y]? We show that this type of question (the change format) exhibits poor measurement properties, in large part because subjects en...

Experimental researchers in political science frequently face the problem of inferring which of several treatment arms is most effective. They may also seek to estimate mean outcomes under that arm, construct confidence intervals, and test hypotheses. Ordinarily, multiarm trials conducted using static designs assign participants to each arm with fi...

Eliciting honest answers to sensitive questions is frustrated if subjects withhold the truth for fear that others will judge or punish them. The resulting bias is commonly referred to as social desirability bias, a subset of what we label sensitivity bias. We make three contributions. First, we propose a social reference theory of sensitivity bias...

Researchers need to select high-quality research designs and communicate those designs clearly to readers. Both tasks are difficult. We provide a framework for formally “declaring” the analytically relevant features of a research design in a demonstrably complete manner, with applications to qualitative, quantitative, and mixed methods research. Th...

Police body-worn cameras (BWCs) have been widely promoted as a technological mechanism to improve policing and the perceived legitimacy of police and legal institutions, yet evidence of their effectiveness is limited. To estimate the effects of BWCs, we conducted a randomized controlled trial involving 2,224 Metropolitan Police Department officers...

Does Counter-Attitudinal Information Cause Backlash? Results from Three Large Survey Experiments – CORRIGENDUM - Andrew Guess, Alexander Coppock

Researchers have increasingly turned to online convenience samples as sources of survey responses that are easy and inexpensive to collect. As reliance on these sources has grown, so too have concerns about the use of convenience samples in general and Amazon’s Mechanical Turk in particular. We distinguish between “external validity” and theoretica...

Several theoretical perspectives suggest that when individuals are exposed to counter-attitudinal evidence or arguments, their pre-existing opinions and beliefs are reinforced, resulting in a phenomenon sometimes known as ‘backlash’. This article formalizes the concept of backlash and specifies how it can be measured. It then presents the results f...

Audit experiments are used to measure discrimination in a large number of domains (Employment: Bertrand et al. (2004); Legislator responsiveness: Butler et al. (2011); Housing: Fang et al. (2018)). Audit studies all have in common that they estimate the average difference in response rates depending on randomly varied characteristics (such as the r...

To what extent do survey experimental treatment effect estimates generalize to other populations and contexts? Survey experiments conducted on convenience samples have often been criticized on the grounds that subjects are sufficiently different from the public at large to render the results of such experiments uninformative more broadly. In the pr...

Candidates for political office in the United States can appeal to constituents in either English or in Spanish. We investigate the consequences of this choice in a series of survey experiments conducted on large, diverse samples of both monolingual and bilingual Americans. We take advantage of parallel advertisements produced in both English and S...

Missing outcome data plague many randomized experiments. Common solutions rely on ignorability assumptions that may not be credible in all applications. We propose a method for confronting missing outcome data that makes fairly weak assumptions but can still yield informative bounds on the average treatment effect. Our approach is based on a combin...

Explanations for the failure to predict Donald Trump’s win in the 2016 Presidential election sometimes include the “Shy Trump Supporter” hypothesis, according to which some Trump supporters succumb to social desirability bias and hide their vote preference from pollsters. I evaluate this hypothesis by comparing direct question and list experimental...

In Coppock (2014), I presented a reanalysis of Butler and Nickerson (2011), a field experiment that tested the effects of providing state legislators district-level public opinion data on their roll call votes for a bill. The reanalysis employed a method introduced by Bowers et al. (2013) to conclude that the Butler and Nickerson estimate of the to...

Although lawn signs rank among the most widely used campaign tactics, little scholarly attention has been paid to the question of whether they actually generate votes. Working in collaboration with a congressional candidate, a mayoral candidate, an independent expenditure campaign directed against a gubernatorial candidate, and a candidate for coun...

Field experiments and regression discontinuity designs test whether voting is habit forming by examining whether a random shock to turnout in one election affects participation in subsequent elections. We contribute to this literature by offering a vast amount of new statistical evidence on the long-term consequences of random and quasi-random indu...

Background: On the U.S. Federal Health Insurance Exchange established by the Affordable Care Act, states with fewer insurers have higher insurance premiums than states with more insurers. This expected feature of a competitive market has not been studied within states, however. We tested the hypothesis that insurance premiums decrease in more compe...

A field experiment carried out by Butler and Nickerson (Butler, D. M., and Nickerson, D. W. (2011). Can learning constituency opinion affect how legislators vote? Results from a field experiment. Quarterly Journal of Political Science 6, 55–83) shows that New Mexico legislators changed their voting decisions upon receiving reports of their constitu...

A small but growing social science literature examines the correspondence between experimental results obtained in lab and field settings. This article reviews this literature and reanalyzes a set of recent experiments carried out in parallel in both the lab and field. Using a standardized format that calls attention to both the experimental estima...

Survey respondents may give untruthful answers to sensitive questions when asked directly. In recent years, researchers have turned to the list experiment (also known as the item count technique) to overcome this difficulty. While list experiments are arguably less prone to bias than direct questioning, list experiments are also more susceptible to...