What does it all mean?
The discussion section of your manuscript is critically important. It is where you pull together all the ‘threads’ of evidence you have presented in the results in the context of the background you presented in the introduction.
Unfortunately, many authors, particularly those from non-English-speaking countries, overlook the importance of this section considering it sufficient to merely present their results and allow the reader to draw their own conclusions. However, presenting your results without describing their implications leaves them open to interpretation and reduces the impact they could have. Journal editors want papers that will advance the field and generate an impact. Therefore, use the discussion wisely to maximize the impact of your findings.
A good discussion will begin by restating the study question and any hypotheses presented in the introduction. This should be followed by a summary of the major findings of your study so that it is immediately clear how you have advanced the field. Start with the most important or relevant finding and then move to progressively less important ones. However, do not yet discuss results that are perhaps controversial or difficult to explain. At this stage you only want to describe the major findings that directly answer the research question you set out in the introduction and/or those that directly relate to your hypotheses.
Avoid making grand statements that are not supported by your data and/or overstating the importance of your findings. The word “suggests” is preferable to “shows,” and the word “proves” should never be used. Also, there should be minimal repetition with the results section, with only brief descriptions of the main findings required before launching into their implications. A mixture of tenses is required, with the past tense used to describe individual results and the results of previous studies, and the present tense used to describe their implications.
Put it in context
The next part is the component of a discussion that is often overlooked and a frequent cause of rejection from journals. Having reiterated your initial question and major findings, you need to describe their relevance and significance. This is where you put your findings into the context of previously published literature and discuss their implications. This part forms the bulk of the discussion section, showing the reader (and importantly, the journal editor) what your findings actually mean in the light of the existing literature and how they relate to the efforts of others.
All possible alternative interpretations of your study should be described and excluded (or at least shown to be unlikely) wherever possible. If alternative interpretations remain viable, the study is considered ‘incomplete,’ or at least ongoing, and experiments to rule out the alternatives or determine which of the alternatives is correct should be described at the end of the discussion section as future research.
Once the major findings have been put into context, any controversial or difficult to explain findings should be mentioned along with plausible explanations for them. It is perfectly OK to speculate here (but not too wildly), but it is absolutely essential that these findings, and any inconsistencies, are discussed and addressed rather than ignored. No new results or terms should be introduced in the discussion section; all findings should be described in the results section and relevant terms will all have been introduced in the introduction section.
Finally, any limitations of the current study should be explained. Peer reviewers are likely to comment on such limitations anyway, so it is best to be ‘up front’ about them and state what they were; doing so might even improve your chances of a positive peer review and thereby shorten the time to publication. The fact that your study has certain limitations is not a problem in itself, and most studies have limitations of some sort. It is therefore important to acknowledge these and describe how they can be addressed in future research. For this reason, the description of limitations is usually followed by a description of future research.
Some journals have a separate conclusions section, but even in those that don’t, the same content should be merged with the discussion and contained in the last paragraph. This final section/paragraph should briefly restate the key findings and their significance, describing how your study represents an advance in the field, but avoiding direct repetition. The novelty and significance of these findings should be mentioned, but again, it is important not to over-emphasize either of these. Future studies should be mentioned where relevant, and can be the subject of the final sentence if the current study is preliminary. If your study is not preliminary, end with a strong statement that summarizes the impact of the study without over-stating its importance.
The figure below, showing excerpts from the discussion section of paper published in The Journal of Clinical Investigation (doi:10.1172/JCI37622; reproduced with permission), shows some of the important components of a discussion section and the concluding paragraph at the end.
- Start by restating the problem/research question and then state the main findings of your study
- Describe results in the past tense, but implications in the present tense
- Put findings in the context of the existing literature to describe their implications
- Describe the implications of all results obtained; do not ignore ‘inconvenient’ ones
- Avoid repetition, introducing new terms or results, and making grand statements about the importance of your findings
- Describe the limitations of your study and future directions for research in the field
- End with a strong statement describing the relevance and significance of your study