What should a PhD dissertation look like?

September 21, 2023

I am supervising several PhD fellows at the moment and have found that I repeat myself in the one-to-one meetings. So I will write blog posts summarizing general advice I give everyone. This post deals with what a PhD dissertation should look like.

The classic Ph.D. dissertation

Dear PhD fellow (in Norway, PhD fellows are employees, not students): All dissertations are different, yours included. You can write it however you want as long as it is good! It will be evaluated by people like me—experts in the field—often with long experience in supervising and reviewing dissertations. There is no right or wrong; go for something “safe” unless you feel incredibly confident. Your dissertation is not the place to experiment with weird things.

This is the classic formula of how a dissertation should look like. There are variations to this theme, but in my experience, it holds for both monographs (the old-style long-format book) and paper-based (typically 3-8 published articles or papers preceded by a long “introduction”).

Introduction: Here, you include your motivation, the main objective, the larger-than-life research question, the answerable sub-questions, definitions of key terms, limitations, scope, primary contributions, and outline.
Theory: You should not write about everything you know or have read. Instead, explain the key concepts you are building on and whatever is necessary to support the argument in the rest of the dissertation. It also helps to explain the “holes” in the literature and why you have decided to (try to) fill them. If you work multi- or interdisciplinary research, you need to pay special attention to terms that may be used differently between fields.
Methodology: This chapter is not meant to explain in detail what you did (the method); that should be part of your papers (for paper-based dissertations) or later chapters or the appendices. Instead, you should focus on explaining and reflecting on why and how you did what you did (the methodology). This is particularly important when doing interdisciplinary or multi-methods research.
Main findings: This can be written in many different ways. Most importantly, you need to make a good story that the reader can follow. It is your job to simplify the complexity of many years of hard work. Find an easy-to-understand structure and connect your various parts to the structure.
Discussion: A key element of a PhD dissertation is to reflect on your work, compare it to the literature, and discuss limitations. Be honest about problems. A PhD project is never perfect, and a good discussion shows that you are aware of what could have been improved.
Conclusion: Remember to answer your research questions! Think about the conclusion as the second part of your introduction. They need to connect. The reader needs to see the “red lines” going through your dissertation from the beginning to the end. You should end with a “future work” section. This is typically where you spot the best future researchers; the ones that have the ability to know where to go next.
Bibliography: Save yourself a lot of trouble; use a citation manager (see below).
Appendices: Embrace Open Research principles and include links to all your material that can be made available somewhere: data, media, publications, etc. The best is to upload such material in a proper repository and persistent identifiers (e.g., DOIs) as links in your document.

The dissertation should not be too long, not too short. It is the job of the advisor to help you get it right.

Who are you writing for?

When you are telling a story—yes, you should think about your dissertation as story-telling—it helps to envisage your reader. It complicates things, unfortunately, that there are many readers of a dissertation:

Committee: The most important readers of your dissertation will be your committee members. After all, they are the ones to approve it or not. You may not know the committee when you start out, but expect it to be someone with expertise in your field(s). Committees are usually set up to have complementary expertise, typically covering different (sub-)fields.
International experts: The second most important group is the international research community you belong to. If you have ambitions of an academic position in the future, your dissertation is your most important “business card”. When I sit on committees for any academic job, we always refer back to the person’s dissertation.
Other Ph.D. fellows: This is the largest group that will read your dissertation in quite a lot of detail. They will try to understand what you have done, learn from your literature review, and find “holes” they can fill in their work.
The “general public”: This is a vague group but consists of various non-experts, including academics from other disciplines, undergraduate students, journalists, and interested people outside of academia.

As you can see, these groups have very different backgrounds. I suggest writing for groups 3 and 4 but keeping groups 1 and 2 in mind. The best dissertations are so well structured and clearly written that they cater to the needs of all groups.

Which tools should I use?

Many people ask about what tools they should use when writing their dissertation. Anything will work, but this is how I would approach it:

Write your dissertation in LaTeX! It has a learning curve as compared to a word processor, but it will save you a lot of time and trouble once your document grows larger and more complex. I prefer to use Overleaf to avoid the trouble of setting up a TeX system locally and to have track changes.
Use a citation manager from day 1. I prefer Zotero because it is open source, cross-platform, and exports BibTeX files that can be used in LaTeX.
Use a grammar checker. I prefer Grammarly these days, which really helps in cleaning up sentences. It also has a plagiarism checker that doubles as finding sources online if you forgot where you copied some text.
Upload support material to a repository. While YouTube and Github can be ok for videos and code, respectively, it is better to use Zenodo, OSF, Dataverse, or similar to get persistent identifiers.
Try to automatize as many things as possible. One example is how I made a LibreOffice script for exporting image files in the correct format.

Of course, many other tools can be used. I would avoid software that uses proprietary formats (I am looking at you, Apple). Your dissertation will be with you throughout your entire career, and who knows, you may want to copy out some text or edit a figure in 30 years from now. A text-based format like TeX is the most secure way of future-proofing your own content.

You should also use open file formats for any data and media you produce. Also, keep copies of the high-resolution source files (for audio, video, and images) and use vector-based formats when possible. It may seem unnecessary now, but I am talking from experience when I say this will help you later in your career.

Start early

The best advice I can give is to start early and write a little every day. Set up your dissertation document the first day you start on your PhD and fill in things continuously. That will save you a lot of time and trouble in the end. Good luck!