I was originally an undergraduate student from pure mathematics and am planning to transition into biostatistics/bioinformatics/statistical genetics. To accumulate experience, I planned to apply for some internships but lots of them require 2 recommendation letters. I have, for sure one of them from my master thesis supervisor. For another one, I am choosing from a Ph.D. student or an assistant professor.

For the assistant professor, I took a 1-month summer project in applied mathematics (ecology) with him. It has nothing to do with biostatistics/bioinformatics/statistical genetics except some programming experiences. I met him once per week face to face.

For the Ph.D. student, I am currently working under him on a topic related to biostatistics/bioinformatics/statistical genetics (collaboration), which will possibly lead to publication. But still, the topic is not directly related to the internship project. I had never seen him face to face due to his different geographical locations.

Who should I ask recommendation letter from? Any suggestions?

  • Unless your program is very weird... There's really no such thing as a PhD Student... You're a postgraduate researcher and phrasing that as though you're a student does everyone a disservice. You'll be spending most of your time researching, not being taught. As such, a recommendation from another researcher you have worked with extensively should hold more weight than a professor you worked with for a month. Commented Jul 28, 2021 at 14:19

3 Answers 3


As a graduate student, I wrote multiple recommendation letters for students who took my courses, where I helped shape their research projects providing above and beyond feedback. I emphasized that recommendation letters would carry more weight (in the context of graduate school applications) from professors to these students, and they made sure to have strong references from professors in that regard.

I think the point of decision here should be who can write you the strongest letter. It might be the PhD student in this scenario based on what you've described here, but only you can determine who will be able to speak to your strengths and qualifications for the internship best. In the case of an internship, I'm unsure how rank will carry influence on the recommendation letters in review. From my experience, the best references are as I've described above: strong and showcasing your strengths/qualifications for a given position. A possible strategy could be to ask the PhD student first, and if they decline, ask the the assistant professor.


Is there a professor in charge of the project you're working on with the PhD student? This professor is a natural person to write the letter. They probably don't know you, but they could ask the PhD student who's supervising you to give them two or three paragraphs (or more, if the PhD student is willing) to include in the professor's letter.

  • 1
    This seems like a good way to get a neutral, meaningless, letter.
    – Buffy
    Commented Jul 27, 2021 at 19:00
  • 1
    @Buffy: the paragraphs from the graduate student supervisor will be included in the letter, and should be neither neutral nor meaningless. Further, the professor may be able to set the research in better context than the graduate student can. Commented Jul 27, 2021 at 19:01
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    I hope you aren't suggesting that the professor include those paragraphs as if they wrote them themself. In any case they must attest to something of which they have no direct knowledge.
    – Buffy
    Commented Jul 27, 2021 at 20:30
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    @Buffy: No, I'm not. I've done this. You write about the project in general terms (hopefully the professor knows something about it) and then you say "my graduate student, who has been supervising the candidate, says ..." and you add the paragraphs from the graduate student. If the professor knows absolutely nothing about the project, this probably won't work, but why is a graduate student supervising an undergraduate without any oversight from professors? Commented Jul 27, 2021 at 20:45

Since you're going at least a little bit out of your original discipline, slightly odd references are not a problem. Undergrads rarely have rock-solid, gold-plated credentials in the first place. If the prospective position required a real hot shot, they wouldn't be hiring an undergrad intern.

And not enough reputation to reply to a comment, but yes, there are "PhD students". At a few schools those folks are just called "grad students" and it's implied that they're trying to finish a PhD (and if Google poaches them, they get an MS if they made it through 36 hours). At most schools in the US, a student has to be explicitly admitted as a PhD student, and this may or may not require already having a Master's degree - I've seen a couple of engineers with a BS and a PhD. Once they complete the PhD qualifier exam(s) they become a PhD Candidate. There are outliers like the (rare!) MFA in Computer Science.

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