Thesis defense questions examiners ask, and how to answer them

This page is for master's and PhD candidates preparing for a defense or viva, and for supervisors running a mock defense. For the format, timing and outcomes, read the pillar guide: thesis defense: what happens and how to prepare.

What questions are asked in a thesis defense?

Examiners ask about what you found, why you did it that way, and whether you understand the limits. Research on doctoral vivas has found that many examiners' questions are predictable and cluster around a small set of themes: the gap, the conceptual framework, the method, the conclusions and the contribution [1].

A predictable question is one an examiner can ask of any thesis, such as "What is your contribution?", as opposed to a specific question about a page, a table or a citation. Prepare all the predictable ones in full. Prepare the specific ones by rereading the thesis with an examiner's eye.

How to structure an answer: the four-part model

Use the same structure for every answer, so you never freeze.

1. Answer. One sentence that directly answers the question. "Yes." "Because the outcome was a count." "Two things."
2. Reason. Why: the logic or the trade-off behind the choice.
3. Evidence. Where the thesis shows it. Give the chapter or page: "Table 4.2 on page 88 shows..."
4. Limit. What the answer does not cover, or what you would do differently. This shows judgment and often closes the follow-up before it comes.

Keep most answers between 30 seconds and two minutes. Stop after part 4. Silence after a good answer is fine.

A model answer (invented example)

Question: "Why did you use interviews rather than a survey?"

Answer: "Because my question was how nurses decide when to escalate care, which is a process question, not a frequency question. [Reason] Surveys would have told me how often they escalate, but not how they reason about it. [Evidence] Chapter 3, section 3.2, sets out that choice, and the 18 interviews produced the four decision patterns in Chapter 5. [Limit] The trade-off is that I can't say how common each pattern is. A survey built on these four patterns would be the natural next study."

That answer takes about 45 seconds.

Questions about your contribution and the big picture

These usually come first and last. They are the questions you should never improvise.

1. Summarize your thesis in two minutes.
2. What is the contribution of your study?
3. Why does this research matter, and to whom?
4. What is the single most important finding?
5. If you started again tomorrow, what would you do differently?

How to answer "What is the contribution of your study?" Name one to three contributions, each in one sentence, and say which chapter shows each. Use the words your field uses for contributions: a new finding, a new method or measure, a new application, a new theory or a test of an existing one. "The thesis gives the first estimate of X in Y, and a validated Z scale" is strong. "It adds to the literature on X" is weak, because every thesis does.

Questions about the literature and theory

6. Which three authors or studies shaped your thesis most, and why?
7. Where exactly is the gap you address? Who else has tried to fill it?
8. Why this theoretical framework and not [a rival framework]?
9. What has been published on this since you finished your literature review?

Question 9 catches many candidates. Search for new papers in the month before your defense and read the two or three most relevant. If one contradicts you, prepare an answer.

Questions about your research question and design

10. How did you arrive at your research question?
11. Why this design (experiment, survey, case study, ethnography...)?
12. Why this population or site? How did you choose your sample?
13. What ethical issues did you face, and how did you handle them?

Thesis defense questions for quantitative research

14. How did you decide on your sample size? Did you run a power analysis?
15. Why this statistical test? Did your data meet its assumptions?
16. How did you handle missing data and outliers?
17. Is the effect you found practically meaningful, not just statistically significant?
18. How valid and reliable are your measures?

For each, know the actual numbers: the sample size, the effect size, the confidence interval, the reliability coefficient. The APA's Journal Article Reporting Standards list what a quantitative report should include, which makes a good checklist of what an examiner may probe [2].

Thesis defense questions for qualitative research

19. How did you decide when to stop collecting data? (Expect a question on saturation or information power.)
20. How did you code the data? Walk us through one code from quote to theme.
21. How did your own position affect the research? (reflexivity)
22. How do you show your findings are trustworthy?
23. Can your findings be generalized? If not, what can a reader take from them?

Know the quality criteria you used and cite them. Lincoln and Guba's credibility, transferability, dependability and confirmability [3] and Tracy's eight "big-tent" criteria [4] are two widely used sets.

Questions about results, limits and future work

24. Which result surprised you most?
25. What is the weakest part of your thesis?
26. How do your results compare with [a named study]?
27. What alternative explanations could account for your findings?
28. What are the practical or policy implications?
29. What would your next study be?
30. How will you publish this work?

Two common traps

• The "weakest part" question (25). Name a real weakness, briefly, then say how you limited its effect and how a future study would fix it. "There are no real weaknesses" fails. So does a ten-minute confession.
• The named-study question (26). If you know the study, compare method and sample first, then results: different results often come from different samples. If you don't know it, say so and ask for a one-line summary.

Personal and closing questions

31. What did you learn from doing this research?
32. Is there anything you would like to add?

Prepare a 30-second answer to question 32. Use it to restate your contribution or correct an earlier answer you weren't happy with.

What if you don't know the answer?

Say you don't know, then show how you would find out. Examiners judge reasoning, not recall.

1. Check the question. "Do you mean the effect in the whole sample or the subgroup?" This buys time and avoids answering the wrong question.
2. Say what you do know that is closest to it.
3. Say how you would find out: the analysis you would run or the literature you would check.
4. Don't bluff. An examiner who knows the answer will follow up, and a wrong confident answer costs more than an honest gap.

Example: "I haven't tested that interaction. My expectation would be a smaller effect in the rural schools, because baseline anxiety was lower there, but I'd want to run the model before claiming it."

How to practice thesis defense questions

Generate likely questions in AI for Research

Defence preparation in the Thesis Suite reads your thesis and lists likely examiner questions by chapter. It costs 3 credits. Use the list as step 1 of the practice plan, then write the answers yourself.

Other parts help with specific questions:

• Find Papers (0 credits) for question 9: search your topic and filter to the last year.
• Similar papers in the Thesis Suite (0 credits) to find studies close to yours that an examiner might name.
• Ask a PDF in My Library to find the exact page that supports an answer.
• Reviewer at master's or PhD level scores the thesis by criterion and quotes weak passages with a fix: these often point to question 25. Standard costs 10 credits per 10,000 words, and the free plan gets a 3-credit preview of the first 3,000 words. See AI peer review.

The Defence Pass ($49 once, 90 days of Pro) covers the run-up to a defense. See pricing.

Limits: the questions come from your text alone. The tool does not know your examiners or their published work, which is where many specific questions come from. Read your examiners' recent papers yourself.

FAQ

What questions are asked in a thesis defense?

Most questions fall into five groups: your contribution, your reading of the literature, your method, your results and their limits, and what comes next. Examiners usually open broadly, for example asking you to summarize the thesis in a few minutes, then go chapter by chapter. Expect at least one question on why you chose your method over an alternative, and one on the weakest part of your study.

How do you answer "What is the contribution of your study"?

Name one to three specific contributions in plain words, say who they matter to, and point to the chapter that shows each one. For example: "The thesis gives the first estimate of X in Y population, and a validated measure of Z. Chapter 4 reports both." Avoid listing every finding. Practice a 60-second version and a two-minute version.

What if I don't know the answer to a defense question?

Say so plainly, then show how you would find out. Repeat or rephrase the question to check you understood it, say what you do know that is closest to it, and say how you would test or look it up. Examiners are judging your reasoning, not your memory. Bluffing does more damage than an honest "I haven't looked at that, but here is how I would."

How long should an answer at a thesis defense be?

Aim for 30 seconds to two minutes for most answers. Start with a one-sentence direct answer, then give the reason and the evidence, then stop. If the examiner wants more detail, they will ask a follow-up. Long answers that wander make examiners interrupt, and they can lead you into areas you have not prepared.

Are viva questions different from US defense questions?

The content is similar: contribution, method, results, limits and future work. The style differs. A UK viva is usually a long, private conversation with two examiners, so questions go deeper into the text, often page by page. A US defense is shorter per examiner, follows a presentation, and spreads questions across the committee. Nordic public defenses add a structured debate with an opponent.

Next steps

• Read the full thesis defense guide for formats, timing and a six-week plan.
• Build your talk with how to build a thesis defense presentation, including backup slides for the hard questions.
• Strengthen the chapter examiners probe most with how to write a methodology chapter.

Sources

1. Trafford, V., & Leshem, S. (2008). Stepping Stones to Achieving your Doctorate: By Focusing on Your Viva from the Start. Open University Press. Based on their earlier analysis of questions asked in 25 doctoral vivas: Trafford, V., & Leshem, S. (2002). Starting at the end to undertake doctoral research: predictable questions as stepping stones. Higher Education Review, 35(1), 31–49.
2. American Psychological Association. Journal Article Reporting Standards (JARS). https://apastyle.apa.org/jars
3. Lincoln, Y. S., & Guba, E. G. (1985). Naturalistic Inquiry. Sage.
4. Tracy, S. J. (2010). Qualitative quality: Eight "big-tent" criteria for excellent qualitative research. Qualitative Inquiry, 16(10), 837–851. https://doi.org/10.1177/1077800410383121
5. AI for Research. Pricing. https://aiforresearch.app/pricing