Defending your doctoral thesis: the PhD viva
Format for defending a doctoral thesis
Every institution will have specific regulations for the thesis defence. In some countries or institutions, the convention is for thesis defences to be public events where you will give a lecture explaining your research, followed by a discussion with a panel of examiners (opponents). Both your examiners and the audience are able to ask questions.
In other countries, including the UK, the oral examination is usually conducted behind closed doors by at least two examiners, usually with at least one being from another institution (external examiner) and an expert in your topic of research. In the UK the supervisor does not participate in the viva, but may be allowed to observe. Sometimes someone from your own institution is appointed as an independent chair. Although it is now becoming more common for the candidate to have an opportunity to give a public lecture in UK institutions, this does not form part of the examination and may or may not be attended by the examiners.
Take the preparation for your viva seriously and devote a substantial amount of time to it. The viva preparation checklist may be useful to help you prepare.
Your institution may offer courses on viva preparation and there may be opportunities to organise a practice viva. Take advantage of these opportunities: they can be extremely valuable experiences.
Things you may wish to take with you
- your thesis – mildly annotated if you wish
- a list of questions that you might be asked and your planned responses
- any questions that you want to ask your examiners
- additional notes which you have made during your revision
- list of minor corrections that you have come across during your revision.
During the viva
Your study will have strengths and weaknesses: it is essential that you are prepared to discuss both. You could think of any weaknesses as an opportunity to demonstrate your skill at critical appraisal. Examiners will seek to find and discuss weaknesses in all theses. Do not interpret criticism as indication of a possible negative outcome.
Examiners have different personalities, styles and levels of experience. Sometimes a candidate may feel that a challenge is made in a confrontational way. Experienced, effective examiners will not be inappropriately confrontational, but some will. Do not take offence. A relaxed, thoughtful, and non-confrontational response from you will help re-balance the discussion. Having an independent chair can help maintain a constructive environment.
Useful tips for during your viva:
- Ask for clarification of ambiguous questions or ask for the question to be repeated if necessary
- Take time to think before answering
- Be prepared to ask questions and enter into a dialogue with your examiners
- Be prepared to discuss your research in context of other work done in your field
- Be ready to admit if you don't know the answer to a question
- Be prepared to express opinions of your own
You are not expected to have perfect recall of your thesis and everything that you have read and done. If you get flustered, or need to refer to notes your examiners will understand. They have been in your situation themselves!
After your viva
There are several possible outcomes of a thesis defence. Most commonly, your examiners will recommend to your institution that you are awarded your degree subject to minor corrections, although in some instances they might ask for more substantial work.