Criteria for an external examiner for PhD viva?

Question

My supervisor has asked me to compile a list (in order of preference) of potential examiners for my viva.

Subject area

How close to my own subject area should I look?

My thoughts so far are that I would like to be examined by someone who has done work that is as close as possible to the topic of my thesis. It's true that someone in a neighbouring field will probably see the flaws in my work more keenly that another might do, and will certainly have no trouble calling me out if I have missed key literature. I do think the thesis is basically sound, and hopefully will pass the critique of such an examiner, and the corrections will be maximally useful.

Someone who's specialism is further away seems likely to ask broader questions. I hope I could answer them adequately, but I'd be less confident of it. It would be frustrating to get lost in aspects that where not really central to the work. I also wonder if the corrections would be somewhat less useful.

Academic esteem

Is there a good reason to want an examiner with high academic prestige? Clearly they need to have enough recent publications that I am clear on what field they work in, but beyond that, does it matter?

Distance

Normally this would be less of an issue, but as there is currently a pandemic, I intend to limit myself to people based in the same country as me. It would be preferable to avoid an examination over video link, even if that was possible. I would rather meet these examiners in person. (I saw this question, but the pandemic changes things rather)

Anything else

Clearly I cannot ask anyone I've co-authored the thesis material with (Or maybe I can, this question seems to think it's sometimes possible, but that seems weird).

Is there anything else that should be considered?

What is the most important factor here?

Answer 1

I think this question is somewhat opinion-based, and different people will weight different factors differently. Some things to think about:

• Personality. Is the examiner someone who will take a broad-brush view of the thesis, or go through it line by line? Are they going to focus on the science, or take issue with your punctuation choices? Some people are notorious for insisting on a large volume of relatively insignificant corrections.
• Reputation. Assuming the viva goes well, your external examiner may be someone you wish to use as a referee in job/fellowship/etc applications. Clearly, there may be benefits to having a 'big name' who is willing to advocate on your behalf.
• Availability. Of course, you want someone who will spend time reading and thinking about your work, and who is available to do the viva on a reasonable timescale. This may be a reason to avoid the 'biggest names'.
• Subject matter. You may be able to guess (based on their past work/interests) which aspects of your thesis a potential examiner is likely to focus on. If you wish to steer the viva towards (or away from!) particular topics, you should choose the examiner accordingly.
• Known quantities. In the UK system, the external examiner wields considerable power: if they want to make your life difficult, they can make it really difficult. With this in mind, it's risky to pick someone who is completely outside your/your supervisor's professional network - you have no idea how they will approach the task. If you can, talk to other recently-viva-ed PhD students in your department - who did they have, and how did they find the experience?

Answer 2

I don't know what things are like at your institution, but here, all viva's are currently over video link whether you like it or not.

Your external should be close enough to your field that they will have a real appreciation of what you are doing, but they don't have to be doing exactly the same thing. Its almost certainly impossible to find someone that will understand everything in your thesis, but then thats part of the test of a good thesis - a skill examiner in an adjacent field shuold be able to understand it without being exactly their specialism. Remember that there will also be an internal examiner that can cover any knowledge gaps in the external.

One reason for choosing a high prestidge examiner is that never again in your career will one person pay so much attention to your work. Its an amazing oppotunity to get close and detailed feedback on your work from an top academic. Its also an oppotunity for you make yourself known to them.