[For the previous post, see here]
Time to wrap up the paper! You have presented your research question, its greater role in the universe, and your findings. Now let’s close the circle and discuss your answers and the questions that still remain, or the questions that you have just discovered. This is what the Discussion section is for.
First, before we get started, a note for those poor souls who work in fields where you are not supposed to discuss your results in the Results section at all. In this case, the Results section is pure data, and therefore the Discussion section usually has two parts, Discussion and General Discussion. The first part is about interpreting each of your results, and the second part is what we will mainly talk about in the following. Sorry for the confusion (not my fault).
And while we are at it, what’s the difference between Discussion and Conclusion? The Conclusion is typically fairly short—it is almost like an echo of the abstract. It is a summary of what you have done, and it adds no new ideas or thoughts. In contrast, the Discussion section can introduce new points and insights (but of course no new results). It can connect the dots in new ways, and show how your findings relate to the broader issue at hand. It can ask new questions.
In the Discussion section, you can remind the reader of your research question and provide a synthesis of your results. You can present the answer to your question and show how it contributes to solving the larger problem that you have painted in the abstract and the introduction. You can suggest further research based on your results. You can contextualize your results (and your research problem) within the literature—you can even cite papers that were not cited in the intro if they help to interpret your results or their significance.
In general, there is a lot of freedom in choosing how to shape the (General) Discussion section. One way to begin is by reminding the reader of the broader knowledge gap and the specific research question of the paper, before proceeding through the results, perhaps grouping them to make certain points, summing up all evidence before arriving at the final conclusion. Or you can begin with a paragraph that recaps your question and your answer, the final conclusion of the paper, and continue with paragraphs that discuss the elements that led to this conclusion.
Whatever the structure you choose, it pays off to plan the flow of the Discussion section in advance at the paragraph level. In my own papers, a very typical formula goes like this: Paragraph 1—quick summary of the problem and the main result(s), Paragraph 2— discuss point A and its deeper meaning, Paragraph 3—discuss point B and its meaning, Paragraph 4— wrap up and finish the paper (see below).
The last paragraph and your final words are tremendously important—do not waste them. First, if the reader has been with you this far, reward her at the end. Second, endings are power positions—the last words of your paper will be remembered by your readers (or, at least those who made it this far and some skimmers that directly jumped to the end). Never waste a power position, never waste an ending! Always end on a high note.
There are some all too common ways of ending with a whimper instead of a bang. These are to discuss limitations of your work in the final paragraph (never do this!), or to say something very vague (never do this either!). As I wrote in the chapter on Methods, all technical limitations should be discussed there, and if they have to be mentioned in the Discussion section, never in the final paragraph. In particular, do not dwell on limitations that everyone knows already and that everyone has (“if we just had more data”). Also, please do avoid vague endings like “further research is needed”. Further research is always needed, this just makes it sound like you didn’t do enough even when you did! Besides undermining the importance of your work, vague statements are never memorable. Say something that you would want the reader to remember.
One good way of ending the Discussion section—and the paper—is to write a short paragraph that recaps your conclusion and the significance of your work. You can even signpost this to the reader and begin the paragraph with the words “in conclusion, we have shown that…” This paragraph can resemble the bottom part of the hourglass of the abstract: what did you find out, what does it mean, and what are its broader implications? How has your work concretely contributed to the big picture? Where have you come from where you started?
[Figure 1: Coming soon. Or not so soon. But closer by almost one chapter now…]