The Discussion Section

1. The Discussion Section

3. 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.

4. Writing the Discussion • Commentary on your study • What did the study show? • What might that mean? • What are other possible alternative explanations for the findings?

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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 • 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

12. Limitations of the Study • Purposes: • Forces you to critique your work • This may help to improve your understanding of the results • Clear assessment of weaknesses shows the reader that you are an objective scientist who understands research • Helps the reader to understand the important methodologic points in the field • i.e. potential biases, importance of power

13. 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

14. 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

15. 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)

16. 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.

17. 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!).

18. Purpose: to interpret your results and justify your interpretation can often be accomplished in four or five paragraphs

19. Common Mistakes in Writing the Discussion

20. Being unrealistically precise in the interpretation • 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… • 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 watching a Kim Kardashian reality show. • Reviewing the entire literature • Pick the most important prior studies • Reference some of the other good ones

21. Overgeneralizing from a small sample or limited population to the rest of the world. • Not keeping the results in perspective--ie, the greatest discovery since the ipod. • Don’t be overly critical of previous studies

22. Failing to address study limitations and sources of bias.

23. 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

24. Structured Discussion – BMJ