32 The Discussion

32.1 Key Insights

The Discussion …

Provides an answer to the central question posed in the Introduction
Explains how the results support this answer
Emphasises the contribution of your work to the advance-in-knowledge

32.2 Structure

Writing your discussion section amounts to taking the “pieces of the jigsaw” from the Results section and assembling them so that the reader can see the “big-picture” of your research conclusions. In this section it is not enough to merely state your conclusions. You must also lay out a convincing case to support them.

Your key findings should be used to provide support for your answer. Refer to the Tables and Figures that are most important. You can also include an explanatory Figure to describe any newly proposed model.

Remember how the Introduction began with a broad perspective on your research topic and zoomed in on the central question of the paper? Similarly, the Discussion begins with a clearly stated answer to the central question and then zooms out to present the supporting results and the “take-home message”. In this way the structure of the Discussion mirrors that of the Introduction.

The answer to the central question should be stated explicitly and without adding to or repeating the state-of-knowledge. At most 1-2 sentences of preamble can begin the Discussion, to remind the reader of the context before stating the answer.

Beginning the Discussion with a lengthy preamble fails to take advantage of ``the power position’’ of the key first sentences.

32.3 Writing Check-list

The following check-list should help you to structure your Discussion section. Consider using a single paragraph to address each of the following headings in order:

32.3.1 Answer

In this paragraph be careful to discuss what conclusions your data support rather than the conclusions you wanted them to support.

What is the answer arising from your primary finding?
- Our results indicate that …
- We found that …
What is the major conclusion drawn from your results?
State if the results are novel
- To the best of our knowledge this study presents the first evidence of …

32.3.2 Support from Primary and Secondary Findings

Is there a single clear result (i.e. your primary finding) that most strongly supports the answer?
- We observed physical interaction between … and … when …
Draw on representative examples to illustrate key conclusions.
- Consider the case of …
When your secondary findings are integrated into the “bigger picture” are they consistent with the answer?
- These findings agree with our model and provide circumstantial evidence of …
Do your secondary findings point to other possible research avenues?
- Our observation that … raises the question whether …

32.3.3 Context

Place your results in the context of the state-of-knowledge
- Our results support the paradigm that …
How do your results confirm or contradict the conventional wisdom in your field? -The differences between our results and those of Crick et al can be explained by …
- These results are consistent with … but suggest that this process is more common than previously thought.
What are the possible natural phenomena (e.g. biological processes) that could explain your results?
- Our findings point to a putative role for … in the development of …

32.3.4 Strengths & Limitations

The best Discussions are characterised by a detailed treatment of this topic.

First highlight the strengths of your study by reminding the reader of the credibility of your approach.
- By taking advantage of the latest … technology to study … we can be confident that our results are …
Anticipate any criticism the reader might
- Nevertheless, even when … is controlled for we cannot exclude the confounding influence of … have by acknowledging any limitations.
If possible you should also address any limitations and explain how these affect your conclusions (if at all).
- Our conclusions are robust to possible … contamination for three reasons: (i) …,
- This effect increases the number of false negative results, thus rendering our conclusions conservative.

32.3.5 Future Work

Having addressed the central question, is every other point raised in the Introduction addressed in the Discussion?
What are the testable predictions arising from your work?
- Given these conclusions we can ask if …
Make recommendations for future work.
- Although this study hints at the existence of …, further confirmatory work is needed.

32.3.6 Relevance & Conclusion

Why are your results important and why should readers care?

Speculate about your conclusions.
- We speculate that … are …
Describe the implications of your research for the broader field.
- These observations in mouse have therapeutic implications for human … sufferers.
Provide recommendations for future research.
- We show that … is suitable for …
Suggest applications of your research.
- We argue that … shows great potential as a new approach to …
Finally, deliver a clear and unambiguous ``take-home message’’
- In this work, we have obtained compelling evidence that … .

32.4 Details

32.4.1 Beginning of the Discussion

The beginning of the first paragraph of your Discussion is a key “power position”. The first sentences are the most important, so start with a high-impact statement of the answer to the paper’s central question. This orients the reader as to what the remainder of the Discussion is going to be about. It may be necessary to use the first sentences to accommodate readers who start reading the paper at this point.

32.4.2 Relationship with Introduction

The Discussion mirrors the Introduction but does not continue it. If you need more background material, the Introduction is probably incomplete. A challenge is to incorporate unexpected results that do not fit the background presented in the Introduction. Think about the overall structure of the paper, such results may be better presented in another paper.

32.4.3 Referencing Tables and Figures

All Tables and Figures should have already been introduced and referenced in the Results section. The exception would be a Figure depicting a model summarizing your results or a new hypothesis implied by them. Remember to reference Tables and Figures by stating the result which is to be found there, not the details of the data.

32.4.4 Multiple Conclusions

Studies which present several answers should do so consecutively. Each answer will follow the same structure, presented with its own set of supporting evidence and defence. Use transition phrases to link the different parts of the story together.

32.4.5 Effective Use of Topic Sentences

To lay out the Discussion, incorporate your outline into the topic sentence of each paragraph. Does each sentence announce what new information will be discussed in this paragraph?

32.5 Ending the Discussion

The end of the last paragraph of your Discussion is a key “power position”. The last sentences of the Discussion act to close the entire paper, and serve as an important ``power position’’ for the paper. Claiming that further work is required, or that “the results open up new research avenues”, is a weak note to end the paper on and is a lost opportunity to communicate the importance of your work.

32.6 Examples

Here are some examples of sentence templates taken from Discussion sections in the literature. Under each broad heading we have provided an example of how the Discussion was begun. We are not concerned with the actual details, but rather how the material is organized to communicate it effectively. Therefore only the non-data parts of each sentence are presented.

```{example, name = “A Partial, but Well-structured Discussion”}

This example of a Discussion comes from a study that investigated a protein having an evolutionarily conserved function, but high sequence divergence. The authors claim that, for key proteins in development, sequence divergence may conceal functional conservation.

The Discussion is clearly structured with each implication receiving its own paragraph. The signals First, …, second, …, and finally, …. help the reader to follow the logic.

Additionally, the closing two sentences provide an impactful take-home message. However, the Discussion could have begun more strongly by restating the main answer instead of immediately dealing with the implications.

Paragraph 1: Explanation of first result and how it relates to the current state-of-

These findings have three main implications. (Importance)
First, our data demonstrate that the capacity of … to … is fully conserved in vertebrates. (First implication)
(20 sentences of elaboration)

Paragraph 2: Second answer, its relevance and advance-in-knowledge.

Second, by examining … , we identified … as the … for establishment of … (Second implication)
(10 sentences of elaboration)

Paragraph 3: Third answer, its relevance and speculation/suggestions for future research.

Finally, this work changes the way we view the role of … in … . (Third implication)
(8 sentences of elaboration)

Paragraph 4: Clear and concise take-home message.

In summary, our work offers insights into the … and … . (Statement of significance)
Importantly, it also provides a proof-of-principle demonstration that … . (Take-home message)


```{example, name = "A Poorly-Argued Discussion"}

In the second example, the authors describe how they teased out the regulatory pathway of a certain gene in a specific cell type. The paper presents many results, creating a challenge in writing a coherent Discussion.

Consider the following five deficits in this example:

- The authors' main message is unclear because the three main answers are scattered throughout the Discussion. A brief overview of these answers in the first paragraph could have helped clarity.

- The results are extensively restated.

- The concluding paragraph begins on a weak note. Beginning with a concise answer, instead of reminding the reader what was examined, would have been more helpful.

- There is also no clear statement of the importance of the work, and using a cliche wastes the important closing sentence.

---
    
Paragraph 1: Presentation of first and second answers.
  
- In this report we have shown that ... and ... physically interact.
- We have mapped the binding activities to ... within each protein.
- ... and ... both independently repressed ... gene expression.
- One mechanism by which ... represses ... is via ... .
- In contrast, ... repressed the activity of both ... and ... 
- Although we did not reveal a functional interaction between ... and ... with regards to ... repression, the ... interaction invites questions regarding how ... might contribute to ... .

_Paragraph 2: Support for first answer.

_Paragraph 3: Elaboration on first answer.

_Paragraph 4: Elaboration on first answer.

_Paragraph 5: Defining deficiencies in this study as targets for future research.

_Paragraph 6: Announcement of third answer.

_Paragraph 7: Support for the third answer.

_Paragraph 8: Introduction of a model and updated state-of-knowledge.

_Paragraph 9: Speculation and future research possibilities.

Paragraph 10: Conclusion.

- To conclude, we have carried out an analysis of ...
- ... and...both...,though the....
- We have shown that ... and ... appear to have a ... .
- Many questions remain, most importantly, those regarding ... .
- {Additional efforts are needed to address these intriguing possibilities.

```{exercise, name= “The first paragraph”} Here your paper begins to zoom-out from the details of your Results section. The first paragraph sets up the rest of the Discussion, where you can delve into a more critical treatment of your key conclusion.

Write one sentence stating the overall Answer arising from your paper’s key results. This must directly address the Central Question of your paper as set out in the Introduction.
Build outwards from this Answer to show how the key results support it. Write one sentence for each of your 2-3 most important results and their interpretation.


```{exercise, name= "The last paragraph"}

The last paragraph of the Discussion places the proposed _Answer_ to the _Central Question_ in the context of the _Big Question_ that you presented in the first paragraph of the Introduction.

- Make a statement of how your study provides a unique insight into the _Big Question_.

- Conclude with a strong statement that either:
  - Provides broad _Speculation_ about your conclusions
  - Describes the _Implications_ of your research for the wider field
  - Provides _Recommendations_ to direct future research
  - Suggests _Applications_ of your research.

All of these types of statements are possible, the choice depends on how concrete you can be.