Preparing for a PhD defence can be challenging and also a bit stressful at times. You keep thinking what the examiners might ask and whether you’d be able to answer the questions convincingly. It’s your work, and by the end of the defence you’d realise that it wasn’t too bad after all, but here are some excepts from various sources that could help boost that confidence during the preparation stage. I have also included a list of possible questions that I put together based on various sources I read prior to my own defence (blogs/forums etc). I have combined the different versions of the same question as I saw fit into ‘themes’ or ‘questions’ with minor edits here and there to keep the flow. I didn’t come up with any of these and I’ve used TM: where I added my 2c worth. I just copy-pasted them into a Word document as I was reading the various resources..so it was just for my own sake at the beginning. Anyway, now that I have started this blog I thought I’d just share them in case someone else finds it useful. If you Google for each sentence I bet you’d be able to find the original source!
Lastly, you may have ended up on this post because you are almost done and looking at defending your work. However, if you still have a bit of time, and I were to select just one suggestion/tip/piece of advice for a successful PhD, it will be PUBLISH, PUBLISH, PUBLISH. This will help you in several ways:
- Makes defending your work a LOT easier since your work has already been accepted by international peers, showing a certain standard/quality. If you have 10 publications for instance, it’s not easy for one examiner to just come and say your work is not up to standard.
- During the publication process you get reviewer feedback, helping you address potential weaknesses. Thesis examiners are not significantly different from good journal reviewers, so this process helps you improve your work, understand what others think about your work, as well as prepare for possible questions that may come up during the oral.
- Makes the writing process much much easier since you can convert the bulk of your papers into middle chapters with minimal effort (you would still need some edits to support the flow). For my own thesis, I think I only had to write ~30% from scratch (bulk of it was the Related Work chapter) since I could use most of the material from my papers. This significantly reduces the amount of time you need to write your final thesis – you publish over several years, so the effort is more spread out reducing the stress level in the last 6 months or so.
- This may not be directly relevant to passing the oral, but what are you going to do after your PhD? You spent a long time working on your thesis, but once you defend and have your title ‘PhD’, what’s next? Having a decent publication list can really help boost your CV and help you land that research job you always wanted!
What usually happens is that the examiners have read the work typically twice, and looked closely at some parts that interested them the most. These are usually the good bits. The examiners have standards to uphold, but they are not out to fail you (administratively, it is a lot more complicated to fail you than to pass you!). In general, they feel good about the idea of a new, fresh researcher coming into their area. You are no immediate threat to them. They have to show that they have read it and they have to give you the opportunity to show that you understand it (you do, of course). And they usually have a genuine interest in the work. Some of them may feel it is necessary to maintain their image as senior scholars and founts of wisdom. Judicious use of the “Good question”, “Yes, you’re right of course”, “Good idea..” and “Thanks for that” will allow that with a minimum of fuss and a maximum of time for champagne drinking.
The phrase “That’s a good question” is useful. It flatters the asker and may get him/her onside, or less offside; it gives you time to think; it implies that you have understood the question and assessed it already and that you have probably thought about it before. If absolutely necessary, it can be followed by a bit more stalling “Now the answer to that is not obvious/straightforward…” which has some of the same advantages.
Be ready for a ‘free kick’. It is relatively common that a panel will ask one (or more) questions that, whatever the actual wording may be, are essentially an invitation to you to tell them (briefly) what is important, new and good in your thesis. You ought not stumble at this stage, so you should rehearse this. You should be able to produce on demand (say) a one minute speech and a five minute speech, and be prepared to extend them if invited by further questions. Do not try to recite your abstract: written and spoken styles should be rather different. Rather, rehearse answers to the questions: “What is your thesis about, what are the major contributions and what have you done that merits a PhD?”. [TM:] In my case my supervisor had asked me to prepare a 20 minute ‘overview’ of my work and that’s exactly what the Chair asked me to do during the oral, but this may not be the case for everyone.
My suggestion is that you try to publish at least 3 papers in international peer-reviewed and ISI-indexed [TM: or Pubmed indexed if you are in the medical field] journals while in the process of conducting your experiments. If you have done that, your impending viva voce will only be a formality as publications in high-impact and indexed journals would mean that your work has already been accepted by international academic peers (TM: and it becomes difficult for a single examiner, perhaps with some strong views on the subject, to fail you! Even if your oral doesn’t go well for some reason and examiners try to fail you, still you would have a strong case to backup an appeal).
Unless there’s something very wrong with your thesis, you should not be and should not feel under attack. A PhD thesis is a kind of apprentice piece. It’s meant to show that you’ve learned the essential skills of the discipline; and at the same time, have contributed something worthwhile and new (in some small way) to that discipline.
The viva, or viva voce, is an oral examination aimed at establishing that the content of a PhD thesis is the student’s own work and that it meets a minimum standard. Faced with a strong thesis, examiners will tend to approach the viva with a view to extending that work and publishing the results.
A good thesis will not be penalised even if the oral defence isn’t up to scratch. The key point to remember about vivas is that failure occurs rarely. Assuming that the thesis was properly supervised, passing a viva is a foregone conclusion.
Your examiners will not be expecting perfection and they will not be seeking to fail you. All they will be looking for is an appropriate level of originality and research competence.
Once you make it to the defence, there are practically only two reason that may stop the committee from giving a final pass:
- They discover that your data, experimental results, or references are fabricated; or
- They discover that you have plagiarized [a significant] portion of your dissertation.
So unless you are guilty of one of the above 2 item, there is really nothing to worry about. I knew all this before my defence, and I was still as intense the day before the defence as I ever was. [TM: My suggestion would be to submit your thesis to an electronic plagiarism detection software like TurnItIn.com to get an idea on this before you submit since you may have copy-pasted stuff, especially in your Background/Related Work/Discussion chapters where you talk about other people's work. In my case I had plagiarized about 30% which is pretty bad (supposed to be under 5/10% I think), but most of the copy-pasted blocks were from my own publications, so that was ok. It’s always better that you find and correct any plagiarism than your examiner].
I do a lot of chemistry thesis vivas in the UK, as internal and external examiner, and they’re a fairly big deal. Failure is rare (particularly if I’m the external – I usually examine in viva as celebration mode), but I’ve been the internal with a few arsehole external examiners. I get quite annoyed if we’re examining a talented student with a strong thesis and the external is nitpicking and trying to trip the person up. You can only really fail someone IMO if both weak thesis and weak student are present. Most other combinations should pass.
Worst case was a guy who did a very solid natural product thesis but performed terribly in the viva, and the external was weighing up failing him. I talked him out of it as it would have been outrageous to fail the body of work, but had to re-examine the guy on my own at a later date because the external was so pissed off with the lad’s performance.
I’ve also done one as internal on a really weak student, with a garbage med chem thesis. Her supervisor was canny, though, and picked a pharmacologist as external. They just talked past one another for 2 hours and the external didn’t really clock how bad the student was. I would have had to have failed her if I was external – the experimental section was so bad as to have been irretrievable.
Focussing on the PhD, what examiners are looking for is what editors are looking for. And so, what are examiners looking for? Examiners are looking for publishable theses, acceptable approaches and research. The PhD will be much more wordy and have appendices that don’t see the light of day in publication, but the phd should look like it will end up as publishable work. As a phd candidate, paint the examiners into a corner to show that the work is publishable – and of course if the work has been published then it is easily shown to be publishable and that makes it easier for the examiner to pass the phd.
Experienced Examiners Expect the Thesis to Pass
Of even more comfort to postgraduate students is the reluctance of examiners to fail a thesis. From our 30 experienced examiners (who had examined more than 300 theses over the last 10–15 years), there were only 10 reports of a failed thesis. There are several reasons given for this reluctance. Primarily, it is the examiners’ realisation that the thesis represents three to four years of effort by a talented student, and that its production has been an expensive process in terms of resources and other people’s time: ‘If the student is any good and the supervisor any good then you shouldn’t fail a PhD. There should be enough “nous” around to guide the student in a way that he/she wouldn’t fail’
Another reason examiners will do everything they possibly can to avoid failing a thesis, or asking for a substantial rewrite, is that they realise that this will require a substantial amount of work for the examiner, the student and often the supervisor: ‘A poor thesis causes me sleepless nights as I know how much work and effort is involved’. Most examiners looked for sufficient quantity as well as quality of work, with the frequent use of the word ‘substantial’. In the sciences, this was often defined in terms of the number of journal articles likely to arise from the work. This ranged from two to four good journal articles—not that the student had to have published these, but that there was sufficient material in the PhD to allow for these articles to be published. Linked with this concept was that of publishability; that is, the PhD was of a sufficient standard that parts of it, or the whole, could be published.
‘If there are two or three good publications you can put your feet up and go for an interesting drive.
For students, the most heartening information is that experienced examiners want them to be awarded the PhD and will go to extraordinary lengths to enable this to happen. The other information is that experienced examiners should be sought for the examination process, not avoided, because of their high degree of tolerance. These two factors arise from the examiners’ experience as supervisors and their ability to judge the standard of a thesis based on a wide range of other examples. As one commented, ‘As an examiner, you are not being a supervisor, but being aware of what students go through to get to that point makes one, hopefully, a wiser, less pedantic person and able to see what’s being achieved. Also, you are able to see the vulnerability of the student’. As another said, ‘I tend to be absolutely forensic when I mark a thesis and then I spend hours worrying about how harsh I’ve been and have to argue myself into a sympathetic and tolerant framework. If you don’t exercise tolerance it’s very easy to mark a thesis’. Students sometimes ignore the best advice of their supervisors and submit theses of inferior quality, yet their general view was that the quantity and quality of the work submitted reflected on the supervisor as well as on the student. They particularly held the supervisor responsible for helping students to deal with predictable difficulties, such as difficulties in writing in English.
1. Based on your findings, what will your next research project be? How would you build on this research? Where do you see this kind of research moving in the future? What are the openings? How could you improve your work?
2. How can your research be used in practice?
3. What would you change if you were to do the study again? If you did it again what would you do differently? What would you do differently if you were setting out to do it today? In hindsight, is there any aspect of the research that you would do differently? Looking back, what might you have done differently?
4. What are the main weaknesses with what you did and why are they there? What are the strongest/weakest parts of your work?
5. What is the main contribution of your thesis? What have been the significant contributions of your research? In what ways does this research make a significant contribution to your particular field of study? What have you done that merits a PhD? Summarise your key findings. What’s original about your work? Where is the novelty? What are the contributions (to knowledge) of your thesis? What is the implication of your work in your area? What does it change?
6. Why did you decide to undertake this specific project? What are the motivations for your research? Why is the problem you have tackled worth tackling? What are the main aims, questions, hypotheses? Where did your research-project come from? How did your research-questions emerge? Why are your research questions interesting or important?
7. Comment on and justify your research methodology. Why have you done it this way? What are the alternatives to your approach?
8. What are the principal findings of this research project? How do they compare the findings of other projects within the field? Who are your closest competitors?
9. How has your thinking changed as a result of this research project? What have you learned from the process of doing your PhD? Has your view of your research topic changed during the course of the research?
10. In one sentence, what is your thesis?
11. What are you most proud of, and why?
12. Where do current technologies fail such that you (could) make a contribution?
13. Where did you go wrong?
14. How have you evaluated your work?
15. How do your contributions generalise?