How to Write an Effective Discussion

Abstract

Explaining the meaning of the results to the reader is the purpose of the discussion section of a research paper. There are elements of the discussion that should be included and other things that should be avoided. Always write the discussion for the reader; remember that the focus should be to help the reader understand the study and that the highlight should be on the study data.

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How to Write an Effective Discussion
Dean R Hess PhD RRT FAARC
Introduction
Elements to Include in the Discussion
State the Major Findings of the Study
Explain the Meaning of the Findings and Why the Findings Are
Important
Relate the Findings to Those of Similar Studies
Consider Alternative Explanations of the Findings
State the Clinical Relevance of the Findings
Acknowledge the Study’s Limitations
Make Suggestions for Further Research
Give the “Take-Home Message” in the Form of a Conclusion
Things to Avoid When Writing the Discussion
Overinterpretation of the Results
Unwarranted Speculation
Inflating the Importance of the Findings
Tangential Issues
The “Bully Pulpit”
Conclusions That Are Not Supported by the Data
Summary
Explaining the meaning of the results to the reader is the purpose of the discussion section of a research
paper. There are elements of the discussion that should be included and other things that should be
avoided. Always write the discussion for the reader; remember that the focus should be to help the
reader understand the study and that the highlight should be on the study data. Key words: publishing;
writing; manuscripts, medical; communication. [Respir Care 2004;49(10):1238–1241. © 2004 Daedalus
Enterprises]
Introduction
You have carefully written the hypothesis. You have
designed the study and collected the data. You have con-
ducted the statistical analysis and grouped the summary
results into table and graphs. But what does it mean? Ex-
plaining the meaning of the results to the reader is the
purpose of the discussion section. Although the discussion
comes at the end of the paper, you should be thinking
about what you will write in the discussion section from
the moment that the study is conceived. Questions that you
will develop in the discussion should be considered from
Dean R Hess PhD RRT FAARC is affiliated with the Department of
Respiratory Care, Massachusetts General Hospital, and Harvard Medical
School, Boston, Massachusetts.
Dean R Hess PhD RRT FAARC presented a version of this article at the
RESPIRATORY CARE Journal symposium, “Anatomy of a Research Paper:
Science Writing 101,” at the 48th International Respiratory Congress,
held October 5–8, 2002, in Tampa, Florida.
Correspondence: Dean R Hess PhD RRT FAARC, Respiratory Care,
Ellison 401, Massachusetts General Hospital, 55 Fruit Street, Boston MA
02114. E-mail: dhess@partners.org.
1238 RESPIRATORY CARE •OCTOBER 2004 VOL 49 NO10

the study’s outset. Why is the study important? How does
this study relate to previous studies? What are the limita-
tions of the study design? There are elements of the dis-
cussion that should be included and other things that should
be avoided (Tables 1 and 2). Most important, always write
the discussion for the reader; the discussion is not a forum
for you to impress others with your knowledge of the
subject. You should be trying to convince the reader of the
merits of the study results.
Elements to Include in the Discussion
State the Major Findings of the Study
The discussion should begin with a statement of the
major findings of the study. This should be the very first
paragraph in the discussion. It should be a direct, declar-
ative, and succinct proclamation of the study results. How-
ever, it should not include data or reference to the study
design. Several examples illustrate the point. In a paper by
Anton et al
1
the discussion begins with the sentence, “Our
results confirm that these nasal and full-face masks are
similarly efficient over 15 min of NPPV with COPD pa-
tients recovering from acute hypercapnic respiratory fail-
ure.”This clearly states the most important finding of that
study. Fluck et al
2
began the discussion section of their
paper with the sentence, “Our findings suggest that ambi-
ent light has no statistically significant effect on S
pO
2
read-
ings and that ambient light’s effect on S
pO
2
is clinically
unimportant.”That is a good example of a direct, declar-
ative, and succinct proclamation of the study results.
Explain the Meaning of the Findings and Why the
Findings Are Important
No one has thought as long and as hard about your study
as you have. As the person who conceived, designed, and
conducted the study, the meaning of the results and their
importance seem obvious to you. However, they might not
be so clear for the person reading your paper for the first
time. One of the purposes of the discussion is to explain
the meaning of the findings and why they are important,
without appearing arrogant, condescending, or patroniz-
ing. After reading the discussion section, you want the
reader to think, “That makes perfect sense. Why hadn’tI
thought of that?”Even if your study findings are provoc-
ative, you do not want to force the reader to go through the
paper multiple times to figure out what it means; most
readers will not go to that effort and your findings will be
overlooked, disregarded, and forgotten.
Relate the Findings to Those of Similar Studies
No study is so novel and with such a restricted focus
that it has no relation to other previously published papers.
The discussion section should relate your study findings to
those of other studies. Questions raised by previous studies
may have served as the motivation for your study. The
findings of other studies may support your findings, which
strengthens the importance of your study results. Stoller et
al
3
discussed their study results in the context of a previous
study by others: “Our finding that changing in-line suction
catheters less frequently is associated with lower cost and
no higher incidence of VAP replicates the findings of a
randomized controlled trial conducted by Kollef et al, upon
which our amended policy was based.”It is also important
to point out how your study differs from other similar
studies. An example can again be drawn from Stoller et
al:
3
“Certainly, differences in the specific criteria used to
define VAP could contribute to the rate differences be-
tween the present study and that of Kollef et al. For ex-
ample, comparison of the criteria for nosocomial pneumo-
nia in our study with the criteria used by Kollef et al shows
similar component features but different rating schemes to
establish the diagnosis.”
Consider Alternative Explanations of the Findings
Despite efforts to remain objective and to maintain equi-
poise, it is easy to consider only those explanations that fit
your bias. It is important to remember that the purpose of
research is to discover and not to prove. It is easy to fall
into the trap of designing the study to prove your bias
rather than to discover the truth. When writing the discus-
sion section, it is important to carefully consider all pos-
Table 1. Elements to Include in the Discussion
State the study’s major findings
Explain the meaning and importance of the findings
Relate the findings to those of similar studies
Consider alternative explanations of the findings
State the clinical relevance of the findings
Acknowledge the study’s limitations
Make suggestions for further research
Table 2. Things to Avoid in the Discussion
Overpresentation of the results
Unwarranted speculation
Inflation of the importance of the findings
Tangential issues
The “bully pulpit”
Conclusions that are not supported by the data
Inclusion of the “take-home message”; save this for the conclusions
section
HOW TO WRITE AN EFFECTIVE DISCUSSION
RESPIRATORY CARE •OCTOBER 2004 VOL 49 NO10 1239

sible explanations for the study results, rather than just
those that fit your biases.
State the Clinical Relevance of the Findings
The reason we conduct studies is usually to improve the
care of our patients. Thus it is important to cast the find-
ings of your study in the context of clinical practice. For
which patients do the results apply and for which do they
not apply? Experimental studies conducted in the labora-
tory usually do not involve human subjects, but the results
may have clinical implications, which should be stated. A
paper by Swart et al
4
gives an example of a laboratory
study, the clinical relevance of which is overtly stated:
“The clinically important measurements, for both screen-
ing and monitoring, are predominantly FEV
1
and FVC,
and the Spirospec and Masterlab 4.0 showed excellent
correlation (r ⫽0.99) and very good limits of agreement
for FEV
1
and FVC. For FEV
1
and FVC the Spirospec and
the Masterlab 4.0 could be used interchangeably.”
4
Acknowledge the Study’s Limitations
All studies have limitations. Unfortunately, the limita-
tions of some studies are fatal flaws that preclude publi-
cation. However, even the best studies in the most prestigious
journals have limitations. It is far better for you to identify
and acknowledge your study’s limitations than to have them
pointed out by a peer-reviewer or a reader (in a letter to the
editor after publication). Fluck et al
2
acknowledged a limita-
tion of their study and used it to make a suggestion for further
research: “We used only healthy white subjects, to minimize
confounding variables. Future research should include testing
subjects with darker skin and subjects whose oxygen satura-
tion is below normal (⬍95%).”
Make Suggestions for Further Research
Although a study may answer important questions, other
questions related to the subject may remain unanswered.
Moreover, some unanswered questions may become more
focused because of your study. You should make sugges-
tions for further study in the discussion section. Labora-
tory experimental studies typically lead to suggestions for
follow-up clinical studies with human subjects. An exam-
ple comes from a laboratory study of oscillating positive
expiratory pressure (OPEP) devices by Volsko et al,
5
who
wrote, “One subject that remains to be explored is how to
determine at the bedside whether a patient can perform
OPEP and, if so, which device to select.”
Give the “Take-Home Message”in the Form of a
Conclusion
What is the “take-home message”? What do you want
the reader to remember from your study? The take-home
message should be the first sentence of your conclusions
section. In some journals the conclusions section is a para-
graph or subsection at the end of the discussion, whereas
other journals (RESPIRATORY CARE, for instance) require a
separate conclusions section. The conclusions section may
also provide suggestions for practice change, if appro-
priate. An example of a well-written conclusion comes
from a study by Apostolopoulou et al,
6
who wrote: “VAP
is a common infection and certain interventions might af-
fect the incidence of VAP. ICU clinicians should be aware
of the risk factors for VAP, which could prove useful in
identifying patients at high risk for VAP and modifying
patient care to minimize the risk of VAP, such as avoiding
unnecessary bronchoscopy or modulating enteral feeding.”
Things to Avoid When Writing the Discussion
Overinterpretation of the Results
It is easy to inflate the interpretation of the results. Be
careful that your interpretation of the results does not go
beyond what is supported by the data. The data are the
data: nothing more, nothing less.
Unwarranted Speculation
There is little room for speculation in the discussion.
The discussion should remain focused on the your data
and the patients and/or devices in your study. If the sub-
jects in your study had asthma, it is usually not appropriate
to speculate about how your findings might apply to other
patient populations. If your study used volume-controlled
ventilation, it may not be appropriate to speculate about
how the findings might apply to pressure-controlled ven-
tilation. If you feel compelled to speculate, be certain that
you clearly identify your comments as speculation: “We
speculate that....”
Inflating the Importance of the Findings
After all of the hard work that goes into a study, it is
easy to attribute unwarranted importance to study findings.
We all want our study to make an important contribution
that will be cited for generations to come. However, un-
warranted inflation of the importance of the study results
will disgust reviewers and readers. A measure of humility
goes a long way.
Tangential Issues
It is important to remain focused on the hypothesis and
study results. Injecting tangential issues into the discussion
section distracts and confuses the reader. Tangential issues
HOW TO WRITE AN EFFECTIVE DISCUSSION
1240 RESPIRATORY CARE •OCTOBER 2004 VOL 49 NO10

run the risk of diluting and confounding the real message
of the study.
The “Bully Pulpit”
Do not use the discussion section to criticize other stud-
ies. Although you should contrast your findings to other
published studies, this should be done professionally. Do
not use the discussion to attack other investigators. More-
over, never preach to the reader.
Conclusions That Are Not Supported by the Data
The hypothesis 3study 3data 3conclusions should
be a tight package. Avoid the temptation to allow your
biases to enter into the conclusions.
Summary
The discussion section gives you an opportunity to ex-
plain the meaning of your results. When writing the dis-
cussion, remember that the focus should be to help the
reader understand the study and that the highlight should
be on the study data.
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