Recently I had a PhD interview for a very good university in Europe. The application was for the School of Mathematics, as I posses a Bachelor's and Master's degree in Pure Mathematics.

During the inteview I was quite nervous as it was a new experience for me and the questions posed were only of technical flavour. Questions about my thesis and a project that I concluded during my studies were asked. I was unable to answer most of the questions, as a lot of time had passed since I did my project and thesis, almost 6 months for the last one. After the interview though, as I calmed down, I realized that the answers to the questions were very easy to produce, though the questions were not at all trivial.

I should mention that a potential advisor commented on my thesis, saying that it was the first time he saw a master student write a thesis covering so much material and with such depth. Moreover, in my thesis I speculate about a potential connection between two theories. A thought that turned out to have some merit as some time later a publication appeared describing somewhat the same connection, (not by me).

Taking the above into consideration, I would like to ask wether the fact that I did not answer to the posed questions could be detrimental for my application. That is, if someone experienced a similar situation.

In case of rejection I would consider applying for US universities, though I will have to wait for a year. Do you think this will have a negative impact on such applications?

  • 3
    This is very hard to say as the role of the interview in decision making may vary strongly from country to country and place to place. In my university (Bologna, Italy) such decisions are usually made based on a previously agreed points system and typically there isn't much if anything on interview behaviour in the points system, so it may not harm you at all. However, in some places the impression that people get from the interview is quite important, although I cannot say anything about your specific situation; competitors may have been even worse or worse in other respects. Jul 1, 2023 at 11:42
  • I was unable to answer most of the questions, as a lot of time had passed since I did my project and thesis, almost 6 months for the last one. Obviously your lack of fluency on your own work (!) will have a negative effect on how academics will evaluate you. You know this yourself. PhD interviews are not social engagements or compatibility tests - they are stiff interviews for difficult jobs. The moral of this story is fail to prepare, prepare to fail . . . As preparation you could write summaries of your major projects to date; what topics you like and why; potential and pitfalls.
    – Trunk
    Jul 25, 2023 at 14:22

4 Answers 4


As stated in one of the comments, it really depends on the university policy. At some universities, the interview is just a pro forma step. In that is the case, your prospective advisor already has you admitted based on your thesis, or the department already admitted you based on a points system. At other universities, all the other stuff is pro forma and only the good word from a potential advisor will get you in. If that is the case, then yes of course your failure to answer questions will likely be detrimental to your application. But the deed is done and there's no point in fretting about it. Just wait to hear from them.

Putting that to the side, being nervous is natural and forgivable, but what is less forgivable is to come unprepared to an interview. I interview lots of candidates, and there's an obvious difference between a candidate who prepared but is shaking nervous, and a candidate that is nervous because they were caught off guard by a question we were obviously going to ask. I have my tricks to calm down prepared but nervous candidates and thus help them do better on the interview. After all, we all want the best candidate, not the best interviewee.

As for applying to the US, having been previously rejected by another university will have no effect on your candidacy. Being unprepared to interviews will have the same effect.

  • cheery.beach7701, thank you for your answer! To be honest, I did not expect questions concerning a project I completed one and a half year before graduation and has nothing to do with my thesis. Do you know though if a gap year affects applications to the US?
    – Prelude
    Jul 1, 2023 at 12:56
  • Every professor has his/her own criteria for what makes a good graduate student, so it's impossible to generalize. However, I think that a main cause of grad students failing is just personal immaturity. So I give points to those who have taken a gap year or years. Others might see a gap year as lack of focus.
    – Cheery
    Jul 1, 2023 at 13:06
  • @Prelude Questions about my thesis and a project that I concluded during my studies were asked. I was unable to answer most of the questions, as a lot of time had passed since I did my project and thesis, almost 6 months for the last one. 6 months is not a lot of time, one can certainly read your thesis to evaluate your "research potential", but one is interested in understanding who is the wirter behind the thesis and if the writer of the thesis is the same person that appeared at the interview ... don't make yourself look like an homonymous of the thesis writer !
    – EarlGrey
    Jul 5, 2023 at 9:26

It could well negatively impact your current application. But it mostly speaks to lack of preparation for the interview and the fact that you haven't thought of those things for a while.

But for the future, it need not be an issue, provided that you spend some time preparing to answer questions that are likely to arise. That certainly includes your own work, but also general things in your field, including some recent developments.

You also need a way to deflect such questions if you aren't prepared. You can, at least, give the background required for an answer, or a framework in which to answer it. But, that, too, requires some preparation. Don't go in blind.

  • Buffy, thank you for your response! I am sure it will show some lack of preparation, but do you think it will be enough to diminish any research potential evidence?
    – Prelude
    Jul 1, 2023 at 14:40
  • I can't predict what others will think, but research isn't an on your feet quiz sort of thing. Certainly your application has indications of success in research.
    – Buffy
    Jul 1, 2023 at 14:57
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    Deflecting isn't quite the right approach, or maybe just not the right word. 8f you don't know the answer, showing that you know how to reason it out in finite time would be one rung down on the ladder, but I wouldn't call that deflection. Jul 4, 2023 at 17:23

As others have said, this will depend on the country/university.

Let me offer a perspective from a position where the interview is directly related to whether you are offered a position or not. In those cases, you may be interested to know that quite often it is easy to discriminate between applicants who still know what they did a few months earlier and who can provide a coherent story with a bit of enthusiasm and those who cannot. The second category, I am sorry to say, is out.

This doesn't mean that the candidates themselves (or you in this case) would not be capable of doing a PhD or would even have been the right person for this position, but it does mean that these abilities and fit did not come across during the interview.

It's not a perfect selection mechanism (and suddenly shouldn't be - and typically isn't the only thing that is being evaluated), but what you are looking for in young researchers about to embark on a PhD is a spark and enthusiasm for research (which typically comes across when people talk about their prior work - or not) and their technical and conceptual comprehension of what they worked on before with the ability to also relay that to others - after all, this person will need to drive their own research project for the next few years which will require self-motivation and the ability to learn new things and integrate them over time into a larger scientific concept plus the ability to discuss science with others is at the core of doing science.

So if this was due to a lack of preparation from your end, do better next time to show that you've got the chops.


Why don't you contact them now via email stating that you were nervous/forgetful and provide an explanation to their questions? Irrespective of the outcome of the interview they might have been genuinly interested in your work. And they might still appreciate an answer. Also, it is always good to not leave any question marks around your research work.

Also a slight different perspective from the other answers: forgetting details about a project of yours or part of your work does not mean you were unprepared. People present in conferences very specific projects that they recently completed and forget details. It is still the work that you completed and maybe moved on to something else.

So, I would follow up via email, which is the expected behaviour if someone asks you a question that you can't answer on the spot. Again, irrespective of the outcome of the interview.

  • So by now, after interviewing other candidates, the comitee may have forgotten the candidate could not answer questions on their own thesis ... and you want to remind them this :) ?
    – EarlGrey
    Jul 5, 2023 at 9:23

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