PhD viva: the defence


  • The PhD viva is what stands between you and successfully completing your PhD research.
  • In the UK, the PhD viva takes place behind closed doors with only you present with the chairperson, internal examiner and external examiner.
  • Preparation for your viva needs to make sense. You should try to participate in a mock viva, watch viva videos and prepare answers for anticipated questions.
  • Show up early to the viva, check out the venue and bring the same copy of your dissertation that the examiners will have on the day.
  • The viva will be like no other assessment you’re used to. Remember you’re the expert so prepare like one.
A handshake in a meeting room to represent the conclusion of a successful PhD viva.
If all goes to plan on the big day, you normally get a congratulatory handshake. Like a pat on the back, it’s validation and recognition of years of hard work. You’re now a member of the club.

It all comes down to this big day. You have submitted your PhD dissertation/thesis for scrutiny by fellow experts in your field. You have dedicated years of your life to reach this moment and, believe me when I say, this is you defending your baby, your research.

In the UK, the thing that stands between you and completing your doctoral study is the PhD viva also known as viva voce or, in plain English, an oral examination.

From the perspective of the viva examiners, the aim is to determine whether you are the one who has authored the PhD dissertation and whether you can adequately defend your work.

How the viva works

The format of your viva can vary slightly between institutions and can be totally different in different parts of the world. For example, in most of Europe, the viva takes place in a public setting. So, your examiners are present in the audience alongside the general public and you present your research to them in the style of a lecture. After you’ve presented your work you are then quizzed by the examiners and a discussion ensues.

Personally, I would have loved to have done my viva this way as it makes sense to me. Science should be shared with the community. I feel that research should be scrutinised by not just the experts but society at large. Why? Because they may see things from a completely different angle to you. Also, it gives you a chance to share and promote your ideas to the general public who have a genuine interest. However, my viva was in the UK where things can be quite different.

In the UK, the viva takes place behind closed doors and the only people present are the chairperson, internal examiner, external examiner and you. Your PhD supervisor should be available but cannot be present in the viva. This is all you. But don’t worry, you are the expert now.


The chairperson is usually someone from your department or school and has some basic knowledge of your field, but has had no direct involvement in your work. They are more of a referee. If everyone plays by the rules then the chairperson really won’t have a reason to get involved. Like a football referee. They make sure the viva runs smoothly and does not overrun and they make sure the questions asked by the examiners are fair.

Internal examiner

The internal examiner will be an academic member of staff from your university and ideally from your department or school. They will need to have some good knowledge of your field and familiarity with your line of research as they will be scrutinising your work. For my viva, the internal examiner was responsible for organising the viva. So, they helped to arrange the date, time and location as well as liaising with the external examiner to notify them of the plans.                                 

External examiner

The external examiner is exactly that. They are an expert in your field belonging to a different university and has had no involvement in your work. Their job is to examine your work and check for accuracy and consistency. They have to be fair and impartial. Even if your research references and objectively criticises the work of the external examiner they must remain unbiased.

Preparing for your big day

It’s important to realise that this is unlike any test or exam you have ever done before. Throughout your education, you have become accustomed to being assessed using an exam paper in a timed situation. In such cases, you revise and study past exam papers in preparation. But how do you prepare for something like a viva? Well, first off, it’s not like a traditional exam. It’s more like a formal discussion about your work. Assuming the examiners have a genuine interest, they will simply ask questions about your research based on curiosity and to fill gaps in their understanding. Weirdly, they behave more like students than teachers, because now you are the teacher! Remember this vital point. You are the expert in the room and have the best understanding of your work in the entire world.

For actual preparation, I look at it like this: if you’re preparing to run a marathon, you practice running. You don’t prepare by playing rounds of tennis. Try to organise a mock viva in the lead up to the big day. When I was a postdoc, I took part in a mock viva to help a PhD student prepare for the real thing and it helped immensely. I didn’t hold back, I asked a lot of questions and tried to make it challenging. My credo is to make it difficult so when things get hard it’s easy.

I also highly recommend watching PhD vivas online. Of course, there are many out there so pick one that you think will be useful to you and watch it. Some vivas are several hours long, mine was 2 hours and 45 minutes long. If you cannot watch the whole thing, try to scan through and pay particular attention to questions asked by the examiners and the way the PhD student answers.

Another great resource to help you prepare is the blog: Top 40 potential viva questions. The question that almost always comes up is to summarise your research. Prepare a response to this question and rehearse it. Go through the other 39 questions and decide which are likely to crop up during your viva and prepare answers for them.

If time permits, do not look at your dissertation for two weeks. This is to give your mind a much-needed break. You’re probably sick of the sight of it by now and just need time away. Take it and come back with refreshed and rejuvenated eyes. You’ll be surprised at what mistakes you notice upon your return.

What to take

  • Yourself, obviously. Show up early and familiarise yourself with the viva venue. Go inside. Have a look around to get a feel for the place. This will be part of the preparation. I highly recommend wearing formal attire as this is your big day so dress to impress. Looking underdressed my come off negatively in the eyes of the examiners as they may perceive you as not taking this grand occasion seriously. If in doubt, check with your supervisor and internal examiner for advice on what to wear.
  • The same copy of your dissertation that was submitted to the examiners. Of course, this may be hundreds of pages, but you can condense this down. My copy was printed two-pages per sheet and double-sided. I also made notes throughout in areas where I believed the examiners would ask questions. Using post-it notes is handy too.
  • It may seem strange but perhaps you may want to prepare some questions for the examiners. I remember asking the examiners after my viva what they thought of my work and performance. This was a chance to get their true opinions out so I could understand the strengths and weaknesses of my research.
  • A list of minor corrections that you have made since submission. You could mention this during the viva to remedy any glaring errors in the examiner’s copy.

The viva

In my experience, the viva felt more like an interview and discussion rather than an examination. The examiners would go through my dissertation page-by-page asking questions along the way. But, almost all of the examiner questions were asked with genuine intrigue without them knowing the answer. So, you begin to give them the answers to teach them about your research. Always remember: you’re the expert.

I was told something during the first year of my PhD by a respected professor. In the beginning, my supervisor is the expert and I am the student. By the end, the roles somewhat reverse and you become the expert. Your supervisor may be looking to you for answers about your research. It’s a similar dynamic during your viva. Once you recognise this, the whole thing becomes so much less daunting. But it’s okay to not have all of the answers. If you don’t know just say so. It’s fine. I said ‘I don’t know’ more times than I ever could imagine. But whatever you do, don’t make up an answer and be honest. A colleague of mine tried to trick the examiners and got exposed. Examiners often can tell when you’re being economical with the truth.

Some examiners can be very empathetic. I’ve heard stories of PhD students having panic attacks during the viva. Examiners often let the student have a break to regather their composure. Other times, you have confrontational examiners. Try to relax and not take it personally. It’s hard, I know. But, the job of the chairperson is to keep the atmosphere as calm as possible.

The actual viva can take hours, there’s no real time limit per se. It will take as long as it takes, so be ready for the long haul. Don’t worry, as you should be able to have breaks where possible. At the end of the day, the examiners have other commitments and a life of their own so they’ll need to go home eventually!

The outcome

Pass with no corrections

A very rare result indeed. Essentially, the examiners think your dissertation is flawless and does not require any corrections. Well done!

Minor corrections

A very common outcome. The examiners are happy with your dissertation and request only a few alterations. It could be that a few sentences or paragraphs need amending here or there. Usually, you have around three months to make the changes which are more than plenty in most cases.

Major corrections

Another common outcome. The examiners feel that substantial changes need to happen to your dissertation. This may be anything from rewriting certain chapters to performing more research and gathering more data and even redoing experiments. You typically get six months to resubmit the changes.

Resubmit for a lower award

This is somewhat rare and I’ve personally never known anyone to undergo a viva and have this outcome. The examiners feel that your dissertation is not up to the standard of doctorate. So, they suggest that you resubmit your dissertation for the award of MSc or MPhil. But you’ll likely know well in advance of your viva if your work will be ineligible for the award of a doctorate. Your supervisor will most likely be the one to break it to you.


Whether right or wrong, I’ve always said that its harder to fail a PhD viva than to pass it. This is rare but possible. If your dissertation contains plagiarised content then you can expect a fail. In most cases, your dissertation will be screened by your university before the viva using plagiarism software. Otherwise, it was decided by the examiners that the work will never reach the level of doctorate. This is an absolute last resort and PhD students are often given a chance to redeem their work.

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Naser Al-Mufachi
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