A Guide to Writing a PhD Thesis

Your thesis is the single document your PhD is judged on. It is not a diary of three or four years of work — it is an argument: here is a question that mattered, here is what was known, here is what I did, and here is what we now know because of it. This guide walks through the thesis from the first months of your PhD to submission and the oral examination.

Start the thesis in year one

Most students who struggle at the end treat the thesis as something that begins when the experiments stop. The students who finish on time write from the start, even if almost nothing they write in year one survives unchanged.

• Keep a living literature review. Every paper you read gets two or three lines in a reference manager (Zotero, Mendeley or EndNote): what it found, how, and why it matters for you. In year three this becomes your background chapter.
• Write up methods as you use them. Protocols, code versions, parameter choices and why you made them are easy to record on the day and almost impossible to reconstruct two years later.
• Turn every milestone into a chapter draft. Your first-year report, upgrade or qualifying exam document and conference papers are early versions of thesis chapters. Write them with that in mind.

Thesis, dissertation or “by publication”?

In the UK, Europe, Australia and much of Asia, the PhD document is called a thesis and the master’s document a dissertation; in the USA the words are often reversed. More important is the format your university allows:

• Monograph thesis: one continuous book-length argument written for the thesis. The traditional format and still the norm in many humanities and social science departments.
• Thesis by publication (article-based or “compilation” thesis): three to five papers, published or submitted, framed by an introduction, a connecting discussion and a conclusion. Common in Scandinavia, the Netherlands, Germany and in many science and engineering departments worldwide.
• Hybrid: some chapters are papers, others written for the thesis. Check your university’s rules on co-authored papers — you usually need a statement of your own contribution to each.