A doctoral candidate prepared for her defence by building a forty-slide deck and rehearsing until she knew every sentence by heart. The presentation went smoothly. Then the first examiner asked: “If you were starting again, what would you design differently?” There was a long silence, then a roundabout answer. The question was not hard. She had simply never considered it, because all her preparation was about what she would say, not what she would be asked.
Defence formats vary a great deal: some are public with a substantial presentation, some are a closed oral examination of several hours with two examiners (the viva), some pass through several committee stages. Your institution's regulations set the procedure. But in almost every format, the questioning is where examiners judge how deeply you understand your own work.
What examiners are really checking
- The work is yours: you understand every choice in it and can explain why.
- You know where it sits in the field: what it adds to existing knowledge.
- You see its limits, and do not become defensive when they are pointed out.
- You can think as an independent researcher: answer questions you did not prepare for.
Examiners are rarely trying to fail you. They are looking for evidence that you deserve the degree.
Reread your thesis as an examiner would
By submission you are usually too close to the text. Two or three weeks before the defence, reread the whole thing in an examiner's frame of mind:
- Read it straight through as if someone else wrote it, noting in the margin what you would ask as an examiner.
- List errors you find: typos, misnumbered tables, missing references. Prepare a one-page errata sheet if your regulations allow; pointing out errors yourself is better than having them found.
- Summarise each chapter in three sentences on a single sheet. That is your map to take into the room, if permitted.
- Catch up on important work published after you finished your literature review. “Are you aware of the recent study by group X?” is a common question.
Question types to expect
| Type | Example | Prepare |
|---|---|---|
| Overview | “Summarise your thesis in two minutes.” “What is your main contribution?” | A two-minute spoken summary and three numbered contributions |
| Motivation | “Why this topic?” “Why does this question matter?” | An answer tied to a gap in the literature, not just personal interest |
| Methods | “Why this sample size?” “Why not method Y?” | Reasons for each major choice and the alternatives you considered |
| Results | “Could these results be explained differently?” | Alternative explanations and why you favour yours |
| Limitations | “What is the biggest weakness of this thesis?” | Two or three genuine limitations and how they affect your conclusions |
| Looking back and forward | “What would you change?” “What comes next?” | One specific change and one concrete next project |
A structure for tough questions
Answering instantly is not always best. This structure helps you stay composed:
- Confirm the question: “If I understand correctly, you're asking about…”. It buys time and prevents answering the wrong question.
- Answer directly in one or two sentences first.
- Give reasons or evidence, pointing to a chapter, table or page where you can.
- Acknowledge limits where relevant: “That is a genuine limitation; in the thesis I addressed it by…, and with more time I would…”.
- Stop. Talking on after you have answered often opens the door to a harder question.
When you do not know
There will be questions you cannot answer. Making something up is the worst response. Honest alternatives:
- “I haven't considered that angle. Thinking about it now, I'd expect… because…” Reasoning aloud shows how you think.
- “I'm not familiar with that study. Could you tell me a little more so I understand the question properly?”
- “That's a good question my thesis doesn't answer; I see it as a direction for future work.”
Examiners value honesty and reasoning over a polished but empty answer.
The mock viva: the most valuable preparation step
Ask your supervisor or two or three colleagues to play the panel, ideally including someone outside your narrow specialism. Ask them to be tough, to interrupt, and to wander away from what you prepared. Record or take notes, then review:
- Which answers ran too long?
- Which answers did not actually answer the question?
- Do you slip into defensiveness, for example starting with “No, but…”?
Two mock sessions a week apart usually help more than ten solo rehearsals of your presentation.
The presentation: shorter than you think
If your format includes a presentation, keep to the time limit and focus on the question, approach, main findings and contribution. You do not need every detail; the examiners have read the thesis. Add a few backup slides at the end for questions you expect, such as supplementary analyses or detailed design diagrams.
On the day: small things that matter
- Bring a tabbed copy of your thesis, your errata list, and paper to note questions.
- Write down long or multi-part questions before answering.
- Drink water and speak slowly. Pausing a few seconds to think is normal.
- Write down any requested corrections immediately afterwards, while you remember them clearly.
Three weeks before your defence, start by writing down the twenty questions you fear most and answering each one aloud in two minutes. The ones that do not come out smoothly are the agenda for your first mock viva.
Câu hỏi thường gặp
How do I prepare for a PhD viva or defence?
Reread your thesis as an examiner would, list errors for an errata sheet, prepare answers to common question types, catch up on recent literature and hold at least one mock viva.
What questions are asked in a thesis defence?
Examiners typically ask about your main contribution, why you chose the topic, your methodological choices, alternative interpretations of results, limitations, what you would change and your next steps.
What if I cannot answer a question in my viva?
Do not bluff. Acknowledge it, reason aloud about how you would approach the issue, or ask for clarification. Examiners value honesty and clear thinking.
Should I point out errors in my thesis before the viva?
Yes, if your regulations allow an errata sheet. Identifying and correcting mistakes yourself shows that you know your work thoroughly.
Is a mock viva worth doing?
Very much so. Having your supervisor or colleagues play the panel and ask hard questions reveals answers that are too long, off target or defensive before the real day.
