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The PhD Viva

The viva voce is the final assessment for a PhD. Unlike other degrees, a doctoral thesis isn't simply marked and graded. Instead, students must defend their work in an oral examination.

The PhD viva can seem like an intimidating process, but it actually serves a very simple purpose: proving that your research is original, that you understand its contribution to knowledge and – most importantly – that your work is your own. It's also very rare for students to fail.

This guide explains exactly how the viva works, what to expect on the day, how to prepare and what happens afterwards.

What is a PhD viva?

The term 'viva voce' is Latin for 'living voice'. It means that your PhD thesis is examined 'live' rather than being assessed as a piece of written work.

This involves answering questions about your research and findings from at least two examiners. In some countries (like the USA) the viva is actually referred to as a 'PhD defence', because the candidate defends their thesis from these questions.

Who attends a viva?

A PhD viva usually involves two examiners: one internal examiner (from your university) and one external examiner (from another university). Both should be familiar with your field and the external examiner in particular should be a recognised expert in your specific research area.

The internal examiner usually acts as the chairperson for the exam, making sure it follows your university's procedures.

Your supervisor doesn't normally attend the viva itself, but they will help you prepare for it and should be around to provide support on the day.

How long does a PhD viva take?

There is no set length for a viva voce exam, but most take between one and three hours.

A longer viva doesn't necessarily indicate any problems with your thesis: it may simply be that the examiners are enjoying the discussion. Equally, a shorter viva may just mean that your examiners are satisfied with the thesis and your responses to their questions.

Why is the viva necessary?

The most basic function of the viva is to prove that your work is original (i.e. not plagiarised). This is especially important because the criteria for a doctorate is to offer a significant new contribution to knowledge.

By discussing your work with you directly and confirming that you fully understand your thesis, examiners can be confident that this is your own research.

Do all PhD students have to have a viva?

Almost always. One exception is for PhDs by publication (as the work in these will already have been through academic peer review). Some countries such as Australia and New Zealand also take a slightly different approach as their location makes it harder to invite external examiners for a face-to-face defence.

The viva format

Universities set their own viva voce processes, but most will follow a fairly similar format.

Before the exam

The first step for the viva is to choose an external examiner to invite. They need to be a senior academic with expertise in the topics you have researched, but not someone you have collaborated closely with during your PhD or who you have a strong personal friendship with (as these might create a conflict of interest).

Your supervisor will normally discuss possible options and then submit the invitation on your behalf. This usually happens just before you complete your PhD.

The next step is to submit your thesis. You'll need to hand in a hard copy (printed and bound) for each of your examiners. It's also a good idea to get one for yourself to annotate and take into the exam.

The gap between submission and viva is usually one to three months. This allows time for both examiners to thoroughly read and consider your thesis and for you to prepare.

Your supervisor/s should offer to conduct a mock viva with you shortly before the real exam. They'll ask the sort of questions an examiner might have about your thesis so that you can practice answering and discussing them.

On the day

Your supervisor will normally meet with you before the viva begins to help you relax and ease any last minute nerves.

The exam room will be somewhere on your university campus that has been booked for the occasion. It will be laid out very similarly to a job interview, with space for you and the examiners to sit with your notes. Drinking water is also normally provided.

Most vivas begin with the internal examiner explaining the rules and regulations as a formality. Either they or the external will then begin asking questions about your thesis.

The examiners will usually help you relax and settle in to the discussion by asking something quite general, such as what interested you in this PhD project or what the most enjoyable part of the research was. Subsequent questions will be more specific, often referring the arguments made at particular points in your thesis.

The examiners will end the viva once they have completed their questions and feel able to come to a judgement. You will then be asked to leave the room whilst they discuss your performance and decide on a result to recommend. This normally takes around fifteen minutes or so.

After the viva

The next steps depend on your viva result. The examiners will invite you back in to explain their recommendation and provide general feedback on your work. This may include advice on whether or not you should seek to publish any of your PhD thesis and what sort of edits or further work might be required to prepare it for that.

Hopefully you'll then be able to celebrate with your supervisor, but they should be on hand to offer their to support and advise you whatever the outcome.

The majority of students have some corrections (usually minor) to make before resubmitting a final version of the thesis to be checked by the internal examiner. Once the final copy of your thesis is approved, you will be awarded your PhD! It's time to look forward to using your new title (and wearing some exceptionally elaborate robes at your graduation).

Viva voce exams around the world

There are a few international differences between viva voces. In some places, it's more common for the viva voce to be a public thesis defence (rather than the private, closed-room, exam favoured in the UK). The core format is usually the same, but other staff, students and friends of the candidate can join the audience.

Our guides to PhD study abroad include information on vivas in different countries.

Common viva questions

The questions your examiners ask will obviously be very specific to your thesis and anticipating them is a big part of your specific viva preparation. There are a few things that are likely to crop up more often than not, though.

Here are some example viva questions, along with some tips for answering them well.

"Why did you choose this PhD project?" / "What interested you most about this topic?"

This is a classic icebreaker: it's an invitation to speak generally and positively about your work. As well as being a fairly easy question to answer (after all, there must be at least something you enjoyed about your PhD) this should also help you channel your passion and enthusiasm for your research as the viva gets going. It's really quite a nice opener, if you think about it.

What it isn't is an attempt to catch you out or a challenge to impress the examiners by coming up with something exceptionally clever. Just be honest and speak from the heart.

"What was the most challenging part of the project?"

This probably won't be the first question you're asked, but it might also come up early in the viva as the examiners ease you into talking about your project. It doesn't mean that they think your PhD is flawed, by the way. All research involves overcoming obstacles. This is an invitation to talk about how you did that and reflect on the practicalities of your project.

Be honest, but remember that part of your goal in the viva is to back up the validity and coherence of your findings. It's not a good idea to suggest that your project met with critical flaws or limitations, unless you can also explain how you adjusted your methodology or objectives to achieve success in spite of them.

You should also avoid flippant or throwaway responses (that goes for the viva as a whole, really). Don't say that the hardest part was getting the thesis printed and bound, even if, a month ago, it really felt like it was.

"What is the original contribution to knowledge made by this thesis?"

This question is highly likely to come up at some point in the viva and it's one you absolutely must have a clear answer for. You should be able to explain in one or two sentences what your contribution is, how it's original and why it matters.

You don't need to be clever or extravagant. In fact, your answer may well just paraphrase a relevant part of the abstract or introduction from your thesis itself. But your examiners really do need to be confident that you can answer this one.

Some examiners might not be so explicit or direct in asking this, so be on the lookout for questions like "why is this PhD important?", "why was this project worth completing?", "what were your main findings?" or "why does this research matter?". If you hear any of those, it's time to deploy the original contribution answer.

"Why did you include / exclude X?"

All doctoral projects need to be selective about what they can and can't include, and successful PhD students need to set boundaries for their research. At some point your examiners will probably want to see the logic behind yours.

Be confident and own your decisions. If there was a particular topic or approach you didn't include, then give your reasons for that.

Remember that there are lots of reasons why something might not make the cut for a PhD and the examiners aren't trying to catch you out. They don't even need to agree 100% with your decisions, but they do need to hear that you had credible reasons for making them.

It may be that there wasn't space to cover everything (in which case you should justify prioritising the material you did include). Or perhaps you felt that there was already sufficient scholarship related to a particular source or concept and your aim was to take the field in a different direction (this is a very good answer, if you can make it convincingly).

"If you were to repeat this project, what would you do differently?"

This question (or one like it) may come towards the end of the viva as you reflect on the project as a whole.

Again, the aim isn't to try and undermine your thesis, but rather to see whether you can constructively critique your own work and approaches. Or, to put it another way, have you learned anything from the experience of doing a PhD? You should have. After all, a doctorate is partly about learning to become an effective researcher and mistakes are a great thing to learn from.

In any case, this shouldn't be too hard to answer. There are likely to be all sorts of things you would do differently in future: from adopting different approaches or directions sooner, to heading off blind alleys or methodological mistakes.

"What do you think the next steps might be for this research?"

Relax, your examiners aren't expecting you to dive straight into another PhD. But they may want to hear where you would take this research next, or what you think other scholars could do to build on your findings. After all, part of the value in a new contribution to your field should lie in what it makes possible, as well as what it is.

It's best to be modest and realistic here, rather than making sweeping claims for how your findings will allow other researchers to reinvent the wheel (unless you have actually come up with a new technique for designing wheels, in which case, go ahead).

"Do you have any questions or comments for us?"

Your examiners will probably end the viva by asking if you'd like to ask them any questions, or say anything else about your thesis. This might seem a bit odd, but it's actually a helpful way for you to revisit or clarify any of your earlier answers.

For example, you might like to acknowledge a specific critique and reiterate your reasons for believing the thesis to be valid in spite of it. Or you might want to confirm that the examiners understood what you meant at a particular point in the previous discussion.

It's not a good idea to try and rehash large chunks of the viva here, but it's fine to pick out one or two things and be assertive. This demonstrates your confidence and commitment.

Equally, you can take the opportunity to ask the examiner's opinions on areas of the thesis that haven't come up, if you wish. This is fine, provided you're confident in those sections and comfortable discussing them.

How to prepare

It may feel like you're at the end of a long PhD journey by the time the viva comes around (and you are) but the oral exam is an important part of your doctorate and you should prepare accordingly.

Whatever else you do or don't do, listen to the advice of your supervisors. They'll have experience of all sides of the process, from sitting their own viva voce to preparing previous students for theirs. Chances are they've also served as internal or external examiners too and will know exactly what sort of questions they'd ask about a thesis like yours.

Here are seven tips for effective viva preparation.

#1 Take a (short) break first

Chances are you've been working very hard on your PhD recently, getting it written up, responding to feedback from your supervisor, making edits, sorting the bibliography (which you still left to the last minute, right) and getting the whole thing printed in time for the final deadline.

Whatever happens next, you've just successfully submitted a PhD thesis and you deserve a break. So take one.

A week or two away from your PhD will be ideal (no, don't take a copy of your dissertation with you). You'll get some mental rest and be in a better place to take a fresh look at your thesis and think clearly about it.

There's no need to feel guilty: the time between submission and viva is partly intended to make this possible.

#2 Read through your thesis

You may feel pretty familiar with your thesis by now but, actually, you aren't. You're familiar with a series of chapters that may well have developed separately over several years. It have been only recently that you wrote them up in their final form, added an introduction and conclusion and turned the whole thing into a dissertation setting out your entire PhD thesis.

You need to know that thesis inside out and be completely familiar with the structure of the dissertation that contains and communicates it: which page a key concept or topic appears on for the first time, where key stages of your argument occur, where you cite or critique particular scholarship, and so on.

At the very least, this means reading your full thesis through at least once. Really though, you should be re-reading each chapter a couple of times and. . .

#3 Annotate key points

The PhD viva isn't a closed-book exam and you're expected to take a copy of your thesis with you. It's perfectly fine to consult it in response to questions, so make that process easy by annotating the most important stages of your argument.

There are lots of ways to do this, but, really, there's no substitute for sticking markers through your dissertation and scribbling in the margins.

If the copy of the thesis you take into the exam room looks like it's survived an explosion in a post-it note factory and then spent several years being read by rough-fingered undergraduate students in the library, well, you're on the right track.

#4 Note down potential questions (and answers)

You'll never be able to guess all of the questions that will come up at your viva, but you should be able to anticipate a few of them. Sketching out some bullet-point answers in advance will help you think critically about your thesis and boost your confidence going into the exam.

Spend extra time on any questions you're concerned about. If there's a point where your argument gets a bit strained or where you think your conclusions might be easy to challenge, have a think about how you'd defend them. Remember that your thesis doesn't have to be perfect, but you do need to be able to make a case for it – so practice doing that.

Incidentally, no one has been able to completely test the hypothesis that preparing for a viva question ensures it doesn't actually come up, but, well, the anecdotal evidence is strong. Prepare anyway.

#5 (Re)familiarise yourself with your examiners' work

The viva is about your thesis, but your examiners will have been selected due to the relevance of their own research and their perspectives will be at least partly informed by it.

It makes sense to consider how their work might inform their attitudes towards yours (this should also help you antitipate some questions, as above).

#6 Definitely take up the offer of a mock viva

Your supervisor/s should offer to arrange a mock viva with you shortly before the actual exam (once you've had time to prepare). This is a really helpful process.

The mock viva won't be anything like as long as the real thing and it won't cover every question your examiners will ask (or necessarily predict any of them). But it doesn't need to.

The most valuable feature of a mock viva is to get feedback on how you answer questions. Your supervisors will be able to spot whether you're coming across as too hesitant or too confident, or whether your answers are sufficiently clear.

#7 Try to enjoy it

Chances are you'll be sick of hearing this advice by the time your exam comes around, but it's true. A PhD viva voce really can be fun.

This is your chance to sit down with two experts in your academic field who have read and carefully considered your thesis and whose attention, for the duration of the exam, is entirely on your research. That's a privilege and it's one you've earned by getting to this stage.

Prepare effectively and give the viva voce the respect it deserves. But, once you get into that exam room, be confident, own your ideas and enjoy the chance to let them take centre stage in a serious academic discussion.

Viva results

The vast majority of PhD students pass their viva. This may seem surprising, but it actually makes a lot of sense.

By the time you're ready to submit your PhD you really will be an expert in your subject area, more than capable of discussing and debating it. You'll also have done so many times before: at conferences, in conversations with your supervisor, and in your own writing.

Your supervisor will also ensure your thesis is ready for examination before they recommend you proceed to this stage. The only exceptions to this will be if you submit against the advice of your supervisor (never a good idea) or if you've over-run the time period for your PhD and have to hand in a thesis that isn't ready (you're unlikely to get to this point unless your PhD has been going badly for some time).

PhD viva outcomes

It's rare to fail a viva, but it's also rare to pass outright. Instead, most students are asked to make some corrections to their thesis.

Here are the possible outcomes of a PhD viva voce:

  • Pass with no corrections – (uncommon) – Your viva has revealed no significant issues with your thesis and the dissertation itself is error-free. Congratulations, you are eligible to receive your PhD now!
  • Pass with minor corrections – (very common) – Your thesis is essentially sound, but there are some minor issues with your dissertation (such as typographical errors, or missing references). You will normally have three months to submit a corrected thesis.
  • Pass with major corrections – (fairly uncommon) – There are some parts of your argument that need to be clarified, expanded or otherwise rewritten. You will normally have six months to submit a revised thesis, but won't need a second viva.
  • Revise and resubmit – (fairly rare) – Your thesis is potentially good enough for a PhD, but it needs some significant work, usually including some substantial additional research. You will have around a year to re-submit an improved and updated version of your dissertation for a second viva voce exam.
  • Be recommended for MPhil – (rare) – Your thesis isn't good enough for a PhD, but it is sufficient for an MPhil (a research Masters that doesn't require a substantial original contribution to knowledge). You may receive the MPhil outright, or after some edits and corrections.
  • Fail – (exceptionally rare) – Your thesis does not meet the required standard for a PhD (perhaps due to fundamental flaws in your data and analysis, or due to evidence of plagiarism) and it cannot be converted into an MPhil. You have failed your doctorate and cannot resubmit your thesis.

Those last couple of results may appear scary but, in practice, it's only a few % of candidates each year who don't pass with corrections. The only way a PhD is likely to fail outright is if you have run down the clock on your registration period, submitted a poorly written thesis based on insufficient data and probably done so against the advice of your supervisor/s. The entire PhD process is designed to prevent this happening.

So relax. The likelihood is that your PhD will pass with minor corrections (or better) and that your next challenge will be deciding what to use your new 'Dr' title on first.

Can you appeal a viva result?

If you think your viva outcome was incorrect or unfair, then you may be able to appeal it with your university. The first thing to do is check their guidelines and appeal process. Your students' union may also be able to support and advise you.

Note that you can't normally appeal on academic grounds. Your examiners' judgement is generally final. It is also difficult to appeal a PhD result if you submitted without the support of your supervisor/s or have otherwise ignored their advice at other points in your project.

You may have grounds for appeal if you can demonstrate that you have been poorly advised or supervised (you will need evidence of this and of the specific impact it has had) or if there was an irregularity in the conduct of your viva (such as interruptions, an unsuitable venue, or a lack of consideration for relevant disabilities or health conditions that may have impacted your performance).

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Last updated 16/12/2020

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