The prospect of defending your PhD work can be more than a little daunting. It represents the climax of many years of hard work, you’ll have to defend a thesis in front of experts in your field and the whole PhD viva process can seem cloaked in mystery.
Maybe you’ve seen a labmate go for their PhD viva to then emerge several hours later, relieved but perhaps slightly dazed. Often it’ll be the case that they’ll have forgotten the specifics by the time they’ve left the room. On top of that, horror stories of bad PhD viva experiences pass through many research groups which are enough to make even the most confident and positive PhD students shake in their boots.
Having had my own PhD viva earlier this year, in addition to discussing experiences with many other PhD graduates, I now want to help you through the process.
Before we begin, I want to offer some reassurance. For most people the PhD viva is not at all the horrible experience we occasionally hear about. Even so, it’s still useful to know what to expect. I’ve therefore put together a series to help others understand the PhD viva process and how to defend a thesis.
Defend a Thesis: Overview of the PhD Viva Series
This first post will be an introduction to the PhD viva process and how to defend a thesis. Upcoming posts will cover:
- Viva Preparation: Common PhD Viva Questions
- What is a PhD Viva Like? Sharing Graduates’ Experiences
- How to Choose Your Examiners
If there is anything specific you’d like covered, please let me know! I’ll be sure to include it. If you’d like to subscribe to get notified of upcoming posts as they’re released you can do so here:
How is a PhD Assessed?
Typically the main output expected at the end of your PhD project is a thesis. You’ve put years of work into your PhD and the thesis details your contributions to your chosen research field. But how is the thesis “marked”? Who will decide if what you’ve written is actually any good?
This is where the PhD viva comes in!
The PhD viva involves you discussing and defending your work with experts in your field. The experts act as examiners to determine whether or not the university should award you a PhD based on your thesis and viva performance. The thesis is the written report submitted for a PhD, and the viva is a means of quality control to ensure that only suitable candidates are awarded a PhD by the university.
Although part of the purpose of a PhD viva is to ensure that the work is of a high quality, just as importantly it’s to check that you were the one who carried it out and that you understand what you were doing!
The PhD viva is therefore essentially an exam during which you’ll have to defend a thesis.
Here is the official “mark scheme” for a PhD at Imperial:
I recommend looking at the presentation which this screenshot came from: sadly I only came across it after my own PhD viva whilst putting together this post!
Steps to Completing a PhD
- Submit your thesis for the examiners to read ahead of the viva.
- Celebrate!
- Have the viva, where you’ll defend a thesis and discuss your research. The examiners will decide from a list of possible outcomes as detailed later in this post.
- Celebrate!
- Make amendments to the thesis as necessary.
- Optional celebration.
- Have the thesis amendments approved by the examiners and/or your supervisor and confirmation sent to the university.
- Upload the final copy of your thesis to the university.
- Eagerly await notification that you’ve been awarded a PhD by the university!
- Celebrate, Dr!
All celebrations except for the one after making changes to your thesis are mandatory!
PhD Viva vs PhD Defence
The words viva and defence are sometimes used interchangeably, but often are used to reference the different ways that the a PhD is concluded around the world.
A PhD viva (technically a viva voce) is a formal examination of a PhD. It’s typical in the UK (amongst other countries) and it is a closed-event between yourself and some examiners.
Across much of Europe it is common instead to have a PhD defence . This still involves expert questioning but can be more of a ceremony and may even be open to the public. You can read about Siddartha’s experience, who completed his PhD in the Netherlands.
I went through a PhD viva and that’ll be the focus of this series. Nevertheless, there is overlap and you may still have difficult questions in a PhD defence, so the content in this series should still be useful no matter where you’re based.
In both a PhD viva and a PhD defence you’ll be expected to defend a thesis which represents the culmination of your work during the PhD.
Who is Present During the PhD Viva?
In the UK it is typical for the PhD viva to include:
- One or more experts from your university (internal examiner).
- One or more experts in your field from another institution to your own (external examiner).
- You!
- And sometimes your supervisor, though in my experience this is quite rare unless you actively ask them to be there.
The main role of the internal examiner is to act as a moderator and ensure that the university’s protocols are upheld. They’ll usually still have some questions for you, but on top of that they’ll make sure that the external examiner(s) are reasonable. They will also take charge of documenting the viva.
Often the external examiner will be more specialised to your field than the internal examiner, so expect them to potentially ask more tricky and technical questions.
As mentioned in the previous section, for PhD defences in other countries the event may be less of an exam (viva) and more of a celebration of your work. These can be a lot more open, with access granted to your friends, family or anyone else who is interested in the topic. I quite like this idea, especially when the research has been publicly funded!
How the PhD Viva is Structured
The structure of the viva will vary but a typical format is shown below. The times in brackets are how long the sections for my own viva were, thankfully not all vivas are over five hours long!
- Introductions (2 minutes) – greeting the examiners and they’ll usually quickly give an overview for how they want the viva to go.
- Presentation (10 minutes) – Not all examiners will want you to give a presentation, it’s best to ask them in advance. I believe many examiners like asking for presentations: both to ease into the exam and also to see how you do at distilling years of work into a short presentation.
- Discussion (Over 5 hours, yes, really!) – the long and potentially scary bit.
- A short break (~10 minutes). You’ll leave the room (or video call!) and the examiners will come to a decision for your PhD outcome.
- Decision and final comments (10 minutes) – where the examiners will tell you what the outcome is of the viva – we’ll cover this in more depth in the next section.
The discussion in the middle of course is the main guts of the PhD viva, and the potentially scary bit. This is where you’ll get questioned about your work and thesis. What you get asked could vary considerably depending on your thesis and examiners.
I’ll save an in-depth discussion of my own viva for another post. In short, I received very few questions relating to the work or any fundamental underlying science. There were practically no questions to quiz my knowledge.
Rather than checking my understanding of the work, the viva was much more of a discussion of how best to present the work in the thesis. We spent roughly an hour going page by page through each chapter. This included suggestions for improvements to figures, changes in terminology and the like.
Possible PhD Viva Outcomes
At the end of the viva the examiners will give you feedback. This will include feedback on your performance in the viva. But as long as they’re satisfied that you carried out the work and that you knew what you’re doing, the bulk of the feedback will in fact revolve around your PhD thesis.
Technically there are lots of potential outcomes, as detailed here:
In reality here are the four main possible outcomes from the viva:
- Pass with no amendments. The examiners didn’t want to make a single alteration to your thesis. Well done you just have to submit the finalised thesis to the university and you’ve finished your PhD! I know a few people who’ve had no revisions but it’s rare.
- Pass with minor amendments Minor amendments include things such as correcting typos, rewording sentences and small alterations to data analysis and presentation. This is by far the most common outcome.
- Referral for resubmission (major amendments). More substantial changes to the thesis are required or further experimental work is required to fulfil the requirements of a PhD. The examiners will decide whether or not this means having another viva too.
- Fail. Unless there are glaring issues or you didn’t actually do any of the research in your thesis yourself, you should be relieved to hear that practically no one ever fails. If you have failed, it usually points to systematic issues revolving around your supervisor: you shouldn’t have been allowed to get to this point. Usually the examiners would recommend that you be awarded a lower degree, such as a masters in research (MRes).
Slightly up the page is a screenshot from my own examiners’ report. You’ll see that I, like most people, passed with minor amendments.
2022 Update: Starting to prepare for your PhD viva? A set of viva preparation worksheets are now available in the resource library. Click the image below for free access!
Making Changes to Your PhD Thesis
Shortly after the viva you should receive the examiner’s report which includes a list of revisions for you to make.
If you’ve got through the viva with a pass, you can breathe a sigh of relief because the hard work is over! In a separate post I’ll be covering how the process to make my own minor amendments went.
No matter the outcome, it is possible that you’d like to make your own changes to the thesis since it’ll have been many weeks (or months) since submitting the draft copy for your viva. On reflection there may be things you’re not happy with. You are welcome to make changes to the document yourself.
If you’re interested in reading more about how to make the corrections to your thesis, read the article dedicated to it here: Minor Corrections: How To Make Them and Succeed With Your PhD Thesis.
After you’ve made changes, the final stage in getting awarded the PhD is submitting your finalised version of the thesis to the university. Shortly afterwards you’ll get the long-awaited notification that you’ve got your PhD!
Should You Strive For No Amendments?
In my opinion it’s not worth the effort of trying to get no amendments.
I’d personally rather spend slightly less time up front, knowing that more than likely I would have to made some amendments. You can never put in enough work to ensure there will be nothing your examiners want changed!
You could spent hundreds of extra hours endlessly going through your thesis meticulously before submission but your examiners can always find something they want you to change. In comparison, my own minor amendments only took two days of work.
Sometimes you’ll see someone mention on their CV that they passed with no revisions but it doesn’t really have any bearing on your PhD. Unlike most other qualifications, there aren’t really grades for PhDs: you either have one or you don’t.
During an early PhD assessment my assessor made a poignant joke about medical degrees: “What do you call the person who graduates bottom of their class in medical school? A doctor!” And it’s essentially the same with PhDs!
If you’d like personalised help with preparing for your PhD viva I am now starting to offer a small number of one-to-one sessions. You can find out more here.
I hope this introduction to PhD vivas and how to defend a thesis has been useful. Let me know if you have any specific questions or concerns you’d like to see addressed in the following posts.
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