The Discussion Section
The Discussion
Overall Purpose:
To interpret your results and justify your
interpretation
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The Discussion
Further Purposes
– It’s the heart of the paper, but keep it as short as
possible.
– Answers the question posed in the Introduction.
– Explains how the answers fit in with existing
knowledge.
– Author can express his/her opinions.
Writing the Discussion
• Should be the least stressful part of creating
your manuscript (seriously)
• Commentary on your study
– What did the study show?
– What might that mean?
– What are other possible alternative
explanations for the findings?
Outline of a Discussion Section
• Summarize major findings in first paragraph
– Statement of the results should reflect the study design,
i.e. stick to ‘associations’ unless it’s a RCT
• Secondary Results
• How do Results Compare with Prior Knowledge?
• Limitations of the Study
• Conclusions and Implications
What Results Mean
• Interpret results and indicate how convincing they
are
– Discuss clinical versus statistical significance
• You are telling your readers WHY your results
matter
• This is a LARGE part of discussion
• Consider all the implications of your results:
clinical, biological, methodological,
economic, ethical
What Results Mean (cont)
• Indicate strength of your conviction: How certain are you?
• These findings demonstrate that effective therapy for
disease X is a reality
• Our results suggest that effective therapy for disease
X is possible
• Don’t be unrealistically precise
• Ex: Applying these results to the 41,253,483 U.S.
adults between ages 30 and 64, we estimate that
8,333,203.6 Americans suffer from…
Secondary Results
• Discuss the most significant secondary results after you
have discussed the primary results
• Synthesize and summarize, don’t just repeat what you’ve
found
• Refrain from discussing results that are self-explanatory or
common knowledge
• Ex: In our study of patients with diabetes and
hypercholesterolemia, more deaths resulted from
heart disease than from lightning strikes
How Do Your Results Compare With
Prior Knowledge?
• Compare to the results of prior studies
– How does your study expand on those studies?
• DO NOT review the entire literature
– Pick the most important prior studies
– Reference some of the other good ones
• Sometimes it is more efficient to present main
features of previous studies in a table
How Do Your Results Compare With Prior
Knowledge?
• If your results disagree with what other
investigators have found, explain why
– Do results differ completely or do they overlap
with other findings?
– Are there important differences in:
–The design of the study
–Characteristics of the subjects
–Way measurements were made
How Do Your Results Compare With Prior
Knowledge?
• DO NOT be overly critical of previous studies
• Remember, the authors may be assigned to review
your study
• Be gently critical by being FACTUAL
• (It is considered bad form to denigrate their
ancestors –let’s ask Dr. Zylke for confirmation)
• Don’t write a paragraph about each of the previous
studies in your subject area
• If there are a few significant/important studies,
describe them in more detail
Limitations of the Study
•
Purposes:
1. Forces you to critique your work
– This may help to improve your understanding of
the results
2. Clear assessment of weaknesses shows the reader
that you are an objective scientist who understands
research
3. Helps the reader to understand the important
methodologic points in the field
– i.e. potential biases, importance of power
Limitations of the Study
• What if you can’t think of any limitations?
– Ask yourself:
–
–
–
–
–
If I could do the study over, what changes would I make?
Was the design rigorous?
Were the subjects appropriate?
Measurements precise and valid?
Follow-up complete?
– Consider ALL potential limitations—from design to
interpretation
-- Many investigators ignore the issue of interpretation
-- Don’t just concentrate on limitations of sample size, or
precision of measurements– being critical of how you
have interpreted your results is just as important
Limitations of the Study
Possible limitations:
– Sample size is too small (under-powered)
– Causality not established (study design)
– Data are collected retrospectively
– Data are self-reported with no record
comparison
– Different methods of measuring the outcome
variable
– Missing potentially important covariates
– Study sample might not be representative of the
larger population
Limitations of the Study
What you can’t list as limitations:
– Your co-authors.
– Your boss.
– Your upbringing.
Study Strengths
– You can often mention study strengths and
unique features right after the limitations (or
sometimes in the first paragraph of the
Discussion section)
– BUT don’t brag (“We have the best-looking and
coolest co-authors”)
The Conclusions
What to provide:
– A one paragraph summary of findings in
relationship to the earlier stated hypothesis.
– How the findings agreed or disagreed with those of
similar previous studies. Why?
– A speculation on what impact of study findings may
have on current research controversies and
theories.
The Conclusions
What to provide:
– A comment on the generalizability of the findings.
– The relevant program and policy implications of the
findings.
– The implications for future research with specific
recommendations.
– Final concluding comments and the quotable main
"take-home" points (but don’t repeat results!).
The Discussion—Overall Summary
Purpose: to interpret your results and justify your interpretation
Guidelines for Constructing the Discussion
 Distill the essence of your study.
- Restate the key result.
- State the main conclusion.
• Be clear about why results support this conclusion.
• Maintain connection with purpose of the study.
 Interpret your study in context of literature.
- Compare with results/methods from related studies.
- Emphasize strengths of study and what is new/useful.
 State limitations/caveats (frankly, without apology).
 Make recommendations.
- changes in practice/policy
- future studies
- include some specifics (methods/population/setting)
can often be accomplished in four or five paragraphs
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More free tips
(because we like you)
– ALL results should be presented in the results
section
– Do not present any new results for the first time
in the discussion
– Methods should be in the Methods section, NOT
in the results section
Structured Discussion – BMJ
Suggested structure for discussion of scientific papers
 Statement of principal findings
 Strengths and weaknesses of the study
 Strengths and weaknesses in relation to other studies, discussing particularly
any differences in results
 Meaning of the study: possible mechanisms and implications for clinicians or
policymakers
 Unanswered questions and future research
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