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.
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.
Example 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.
Checklist 1. Start by restating the problem/research question and then state the main findings of your study 2. Describe results in the past tense, but implications in the present tense 3. Put findings in the context of the existing literature to describe their implications 4. Describe the implications of all results obtained; do not ignore ‘inconvenient’ ones 5. Avoid repetition, introducing new terms or results, and making grand statements about the importance of your findings 6. Describe the limitations of your study and future directions for research in the field 7. End with a strong statement describing the relevance and significance of your study