how long should a phd thesis conclusion be

How to write a PhD in a hundred steps (or more)

A workingmumscholar's journey through her phd and beyond, concluding the thesis.

I am co-supervising a PhD student who is handing in her thesis for examination in November. She is currently revising her whole thesis, working towards the conclusion (and finally, the introduction). Conclusions can be tricky things to write – pulling something as big as a PhD dissertation together into a final, clear chapter is not easy. It is both an intellectual and an emotional challenge, as conclusion-writing comes towards the very end of the process, and you are so tired, and probably feeling like there are no more coherent words or sentences in your brain. This post reflects a little on what a thesis conclusion is for, with some thoughts on how to construct one that does justice to your meisterwerk .

To begin with, let’s think a bit about what conclusions are for in a piece of written work. In undergraduate studies, students are typically taught that conclusions are summaries . You restate the thesis, or main claim, of your paper, reiterate what each paragraph has said that contributes to that argument, and then bring it all together with a firm final sentence or two that says something about the relevance of the paper, or argument. There should be no new information, just a summing up of what has already been said. Sometimes you are allowed recommendations, depending on the discipline. It makes sense, then, that we progress into postgraduate studies believing that we are writing summaries whenever we conclude (a paper, or a journal article, or a thesis). I have seen many conclusions like this in postgraduate, postdoctoral and early career writing. But, unfortunately, at these levels conclusions that merely summarise a paper the reader has just read are not adequate, or suitable . A shift is needed.

As Pat Thomson usefully argues in this post about writing a thesis conclusion, the conclusion to a thesis (or journal article) is not a summary of the whole . The summary part of a thesis conclusion should ideally be quite brief, and used rather as a springboard to the real work of the conclusion: using the preceding writing and research to show how the study has addressed the research questions, and in so doing, how it has made a valid, and useful, contribution to knowledge .

A strong conclusion shows your readers what your research means within the context of the field you have referenced in your ‘literature review’, and how in answering your research questions you have been able to speak back to this body of research in which you have located your own study. It answers your research questions, succinctly and clearly, so that your readers understand the overall claims of your study, the focus of your argument, the basis upon which you have advanced your argument, and the significance, meaning or value of that argument to your (their) field. It discusses – argues – for the place of your research within your field, and the contribution it is making.

There are a few ways in which you can approach writing such a conclusion (and Pat’s post above is very helpful here). There are also a few guidelines to consider in writing this vital part of your thesis.

To begin with, you do need to bring your reader up to speed with the thesis thus far . Examiners and other readers are unlikely to read your whole PhD in one go, so ending each chapter with a brief summary, and starting the next one with a short section that connects the present chapter to the previous one is a good idea for creating coherent connections between chapters, and is helpful for your readers. Thus, you should begin your conclusion with an overview, or brief summary, of the argument thus far.

Then, consider your research questions : what did you set out to do in this project or study? Your research questions could make useful sub-headings here, at least in a first draft, to help you organise your thoughts. Starting here, you can begin to pull out the answers you have found (in the ‘analysis chapter/s’) so that you can discuss the implications of your findings, their relevance in relation to your overall argument, and the way in which what you have found relates to the body of research to which you have connected your study. No new information : just an analytical discussion of selected aspects of your findings that are useful for answering your research questions, and further consolidating your argument.

Perhaps you have recommendations , on the basis of your findings and their implications for practice, and/or further research. You could include a section on these, discussing a step further the possible implications of your research in relation to your field. Something else that may be relevant to include here could be limitations to the size or scope of your findings: are there any that your readers need to know about, so that they don’t expect your study to have done something other than what it has done? Don’t just list all the things you could have done but didn’t do: think carefully about pertinent limitations that may represent counter-arguments you could defend or mitigate against.

At the end of the end, consider your argument again : what has your thesis claimed and to what end? Try to end your thesis with a paragraph that reiterates not just what your thesis has argued, but WHY this argument has relevance, or import, for your readers. What do you hope the outcome of your research will be? Why are you so passionate about it, and why do you think others should care too? Read a few thesis conclusions to get a sense of different ways of doing this, and check out Pat Thomson’s posts on conclusion writing , too. Then write a draft and share it with your supervisor for feedback.

It’s worth really taking your time and not rushing this chapter, even as it comes at the end when you are tired, and really just want to be done. End on the highest note you can: you owe yourself that much after all your hard work getting there.

Writing the Dissertation - Guides for Success: Conclusion

Writing the Dissertation Homepage
Overview and Planning
Research Question
Literature Review
Methodology
Results and Discussion
Getting Started
Annotated Example
What to Avoid

Overview of writing the dissertation conclusion

The conclusion is the final chapter of the dissertation. It serves to reinforce your main argument and findings, before considering the wider implications of your research. Along with the introduction, it’s often the shortest chapter in a dissertation, but it is a chapter in its own right and should be given due care and attention.

Even so, the conclusion of a dissertation is sometimes hastily thrown together, culminating in a perfunctory and uninspiring end to such a substantial piece of work. Just like how nobody likes a bad ending to a movie, you want your conclusion to be an accurate and positive reflection of your dissertation that leaves your reader with a clear and satisfying end to the work.

Disciplinary differences

Please note: this guide is not specific to any one discipline. The conclusion can vary depending on the nature of the research and the expectations of the school or department, so please adapt the following advice to meet the demands of your project and department. Consult your supervisor for further guidance.

Guide contents

As part of the Writing the Dissertation series, this guide covers the essentials of writing a strong conclusion, giving you the necessary knowledge, tips and guidance needed to leave a positive impression on your markers! Here’s what to expect:

Getting Started - Defines the overarching purpose of the conclusion.
Structure - Breaks down the conclusion's 'narrow to broad' structure in two main parts.
Annotated Example - Provides a sample conclusion with notes to highlight the strategies the writer uses.
What to Avoid - Covers a few frequent mistakes you'll want to...avoid!
FAQs - Guidance on first- vs. third-person, use of secondary literature and more.
Checklist - Includes a summary of key points and a self-evaluation checklist.

Training and tools

The Academic Skills team has recorded a Writing the Dissertation workshop series to help you with each section of a standard dissertation, including a video on writing the dissertation conclusion (embedded below).
The dissertation planner tool can help you think through the timeline for planning, research, drafting and editing.
iSolutions offers training and a Word template to help you digitally format and structure your dissertation.

What is the conclusion?

The conclusion isn’t simply a brief recap of your previous chapters. Instead, the conclusion revisits your primary research purpose – your research question(s) and/or hypotheses – and summarises and synthesises the main research findings, or areas of discussion, to reinforce how your dissertation responds to that purpose: how does it answer question X or prove argument Y to be correct?

The conclusion then moves beyond the immediate confines of your research to engage with the wider impact and relevance of your work. That is to say, you feed the work you have completed back into the wider context to emphasise how your research has advanced our understanding of this area. This is your final opportunity to leave a positive and lasting impression on your reader, so it’s important that your conclusion captures the essential information in your dissertation and emphasises its value in the relevant profession or field of research.

Structuring a conclusion

Whilst the conclusion of a dissertation is a chapter in its own right, it’s important to consider the role that the conclusion plays in the entire structure of your dissertation. You might recognise the shape below – what is sometimes called an ‘hourglass’ structure. This represents a typical structure for an essay or dissertation. Below, we'll explore what this shape suggests about earlier sections of the dissertation as well as the conclusion.

Hourglass shape with 'Introduction & Literature Review' on broad to narrow section; 'Methods' and 'Results/Discussion' in narrow section; and 'Conclusion' in narrow to broad bottom.

Figure 1: The ‘hourglass’ shape that symbolises the broad-to-narrow, then narrow-to-broad structure of a dissertation, and academic writing in general.

Introduction and literature review

Broad to narrow – eases the reader into the discussion by introducing them to the broad situation within which your research sits.
Narrows the focus through the literature review whilst maintaining a direct interest in the wider research context.
Arrives at a narrow focus towards the end by clearly stating what your focus is, what research problem you are going to address, how you are going to address that problem and what your argument and findings are.

Main body (methodology, results and discussion)

Narrow focus – provides the finer details of your dissertation by isolating particular aspects to discuss and scrutinise, such as the details of how your study was designed.
Driven by the results of your study, with secondary material used to contextualise the meaning and significance of your findings.
Narrow to broad – reinforces your main argument and findings, then...
Broadens out by considering the wider implications of your work for the relevant profession or field of research.

A structure in two main parts

We’re going to break the conclusion down into two main parts:

1) A summary and synthesis of your main findings or discussion points that directly respond to, and address, your research question(s) and/or hypotheses. For this reason, it’s often useful to start by briefly repeating the research problem you’ve addressed. This constitutes the narrow part of the conclusion.

2) Engagement with the impact and relevance of your research to the wider, relevant context . This constitutes the broader part of the conclusion.

Let’s look at both in more detail.

Summary and synthesis

To write an effective conclusion for your dissertation, you need to do more than simply repeat the main points and findings of your research. Instead, you need to summarise and synthesise (definition below) your main findings and points of discussion, forming a cohesive picture for your reader that brings the different elements of your research together. This helps your reader to understand how you have reached a certain answer, or why you think your argument is correct.

It’s often useful to start with a brief recap of the research problem before stating how your dissertation has responded, in some way, to this problem by synthesising the main findings and discussion points. For example:

Despite extensive research on the application of tool X, this dissertation has noted an absence of rigorous research on how this tool can be applied to demographic Y. Considerable research demonstrates the strengths and weaknesses of applying this tool when working with various demographics, particularly A and B, but the different demands associated with demographic Y restrict the suitability of these findings for this age group. In response, this dissertation has…

Following this, you need to outline how your dissertation has responded to this problem by summarising and synthesising your main findings and/or discussion points and reinforcing your main argument. Try summarising every one of your main findings or discussion points – keep it brief (one or two sentences) – and then, where possible, try and condense and connect this information to form a brief portrait of your dissertation. See ' Annotated example' for more on this.

Wider, relevant context

Once you have reinforced your research focus and your argument by summarising and synthesising your main findings, you need to relate your research to a wider, relevant context . This might include:

‘Returning’ to the introduction

As stated earlier, you conclusion shares a close relationship with your introduction with both acting as bookends that frame your entire dissertation – like the first scene and last scene of a film. For this reason, you need to return back to your introduction by revisiting the broad, but relative, themes that opened your dissertation as a way of contextualising your argument and results.

Ask yourself the question, ‘What do we now know that we didn’t at the start?’ The argument and findings won’t be a revelation to your reader, but framing them in this slightly broader context helps to reinforce the significance and contribution of your work. This brings your work ‘full circle’ and creates a neat symmetry to your work – a narrative thread for your reader to follow.

Recommendations for future research

Where necessary, it’s a good idea to include some suggestions for relevant future research that you think will help to further advance our knowledge of the research area. Don’t commit too many words to this. You simply need to state what contributions to the research field might be worth pursuing in the future and how this might further enrich our understanding of the topic. This serves to emphasise that your work is part of an evolving landscape of research, thus engaging with the wider context. This can often feature in the discussion chapter, rather than the conclusion (see our Writing the Results and Discussion guide for more).

Recommendations for practitioners

Depending on the nature of your research, it might be necessary to suggest some recommendations for relevant professionals and industry practitioners based on your findings. Remember these are only recommendations, and they must be consistent with your findings. Briefly mention how each recommendation would serve to address and, potentially, solve a problem faced by professionals. This helps your reader to understand the real-world implications and relevance of your work. Like recommendations for future research, this can often feature in the discussion. Consult your supervisor for discipline-specific guidance.

Annotated example

Take a look at this annotated example to see how the structural components discussed in the 'Structure' tab fit together to form a conclusion. This is only a short example, and your conclusion might be longer and slightly more detailed, but this gives you an idea of the flow and structure.

By focussing on the Arab Spring uprising, this dissertation has demonstrated the ways in which social media animates forms of civil empowerment through collective political action. Whilst other examples could have been used, this dissertation has highlighted how participants in the Arab Spring coordinated a strategic network of communication, drawing on Facebook, Twitter and YouTube in both distinct and interrelated ways. By adopting social media in such a way, the Arab Spring not only demonstrates that social media can have a profound impact on forms of civil empowerment, but can also become a powerful political tool when deployed in a strategic and coordinated manner.

As outlined in Chapter 3: Methodology and Chapter 4: Results, this study collected quantitative data, such as the number of likes, retweets and views, to measure the reach of social media interactions on the Arab Spring uprising during a three month period. Qualitative data was also collected through the language and rhetoric employed by citizens posting comments, and the content of videos posted on the social media sites in question. This mixed-methods approach, along with the focus on three social media platforms, provided a triangulation of data that strengthened the depth of the research and allowed for a more nuanced portrait of how social media, when deployed in a coordinated way for a particular event, forms an interconnected network of channels through which information can flow freely. As evidenced by the quantitative data, with posts and retweets reaching their millions, the use of social media had a cumulative power with the Arab Spring by spreading the civil unrest and galvanising support for the cause.

Whilst the Arab Spring only represents one case of the relationship between social media and civil empowerment, this case study shows how the Arab Spring played an influential role in the mobilisation of the hashtag movement and the digitisation of civil activism. This is most clearly exemplified by the Me Too movement, supporting the fight against sexual harassment and assault, and Black Lives Matter, fighting against the racial oppression of black people. In examining the role of social media on these and other such cases of civil activism, perhaps a systematic comparison between social media and traditional forms of media, such as newspapers, would provide further opportunities to assess the relationship between social media and social activism.

Future research should also further explore the tension between social media and political censorship. Indeed, despite social media’s obvious potential as a tool for civil empowerment, Chapter Five: Discussion also pointed to the dangers of how oppressive governments can respond to the apparent threat of civil activism through aggressive forms of censorship. Moving forward, social media platforms must defend the freedom of its users to engage in socially active ways, and understanding the intersection between social media and political censorship is crucial to defending this freedom. Only by preserving this freedom can social media, and the internet in general, continue to realise its primary function as an open sources of communication that evades the restrictive censorship of traditional gatekeepers.

What to avoid

This portion of the guide will cover some common missteps you should try to avoid in writing your conclusion.

Excessive detail

The conclusion isn’t the place to repeat detailed statistics or retrace the finer nuances of an argument. You simply need to reinforce the main findings and the essential information in your dissertation. Only you can determine what you think is a necessary level of detail in your conclusion, but look at the following two examples as a guide:

Excessive: The results showed a considerable increase from Sample A to Sample E. As expected, Sample A started low with only 6 per cent. Sample B then showed an increase of 20 per cent, with Sample C then reaching 36 per cent to show a further increase of 16 per cent. Sample D furthered this trend, reaching 59 per cent. Sample E then reached 82 per cent, showing a 23 per cent increase from the previous sample.
Improved: The results showed a considerable increase of 76 per cent from Sample A (6 per cent) to Sample E (82 per cent) with samples C to D and samples D to E both showing the largest increase of the study with a 23 per cent rise.

New information

You should avoid presenting any new information, such as primary data or theories, when writing your conclusion. Any primary or secondary material you deem important enough to state in the conclusion (although avoid excessive detail as stated above) should be evident in your results and/or discussion chapters.

'In conclusion...'

Whilst it might seem logical to start your conclusion with ‘In conclusion’, it’s best to avoid this. It’s not strictly wrong to start with ‘In conclusion’, ‘To summarise’, or some other variation of such phrases, but it reflects a somewhat lazy and clichéd approach given its excessive use.

The start of your conclusion should be obvious for two main reasons. Firstly, the chapter heading ‘Conclusion’ serves as a clear indication to your reader! Secondly, your conclusion should signal a rhetorical shift in your writing to a more reflective register. For example:

This dissertation has considered the complex ways in which…

The use of the present perfect tense here signals this shift to a reflective register.

Don’t state your core argument and main observations for the first time in the conclusion chapter. This is sometimes mistakenly employed as a way of maintaining a sense of mystery before the grand reveal at the end – like the dramatic third act of a play or the final twist in a film. Academic writing is not driven by the same intrigue as narrative storytelling. Instead, the ‘end’ or conclusion in a dissertation or written assignment should be clearly signposted early on – the abstract and the introduction – as a way of focusing the reader’s attention.

Q: How long should the conclusion be?

A: Roughly 5-10% of the dissertation’s word count (usually nearer the 5% end). So, for a 10,000 word dissertation, you should aim for anything between 500 words to 1,000. You should, however, be flexible with this. As always, it depends on the nature of your dissertation and the expected conventions in your department or school. It’s always worth seeking advice from your supervisor, but it’s safe to say that – along with the introduction (again dependent on the nature of the dissertation) – it’s often the shortest chapter in the dissertation.

Q: Should the conclusion include references to secondary literature?

A: Yes, but only when necessary. As noted in ' What to avoid' , you shouldn’t be bringing in new data, theories or information, which means you will likely revisit previously discussed work in light of your own findings and argument. Although you have already mentioned and cited the original work, it’s good practice to cite them again. This is also imperative in cases where you have cited more than one piece of work from the same author or authors. So, for example:

These findings support the work of Jones (2010) in which X and Y were both seen to…

Q: Should the conclusion be in the first-person or third?

A: It depends what you’ve been using throughout your dissertation – it’s important to be consistent. Typically, third-person is used in academic writing, although first-person is accepted in some disciplines. For instance, certain genres, such as reflective writing, demand the first-person. Consult your supervisor for further guidance.

The conclusion is your final chance to leave a positive impression on your reader, so it’s important that you conclude in a clear and engaging manner. Rather than simply repeating the main content from your previous chapters, you should be summarising and synthesising your main findings and discussion points and bringing them together to reinforce your central argument and respond to any research questions or hypotheses you have. You should then engage with the wider, relevant context by returning back to where you started in your introductory chapter to answer and consider the question, ‘What do we now know that we didn’t before?’

Here’s a final checklist for writing an effective conclusion. Remember that not all of these points will be relevant for your conclusion, so make sure you cover whatever’s appropriate for your dissertation. The asterisk (*) indicates any content that might not be relevant for your dissertation. To save your own copy of the checklist to edit, please use the Word document, below.