A Five-Minute Guide to Ph.D. Program Applications

If you spend five minutes reading this article, you'll learn how to make your Ph.D. program application the strongest possible. Why five minutes? Because it's probably the longest that anyone will spend reading your application.

I've now served on Ph.D. admissions committees for the past three four years as a professor at two different universities (and in two different kinds of departments: computer science and cognitive science). So far, I've evaluated around 600 Ph.D. program applications across both kinds of departments, which means reading 600 statements of purpose and 2,000 recommendation letters (3–4 per application).

[Update in Dec 2020: in the years since this article was first written, I've probably read a few hundred more applications and rec letters.]

This article should take you five minutes to read, which is probably the longest that anyone will spend reading your application. When I serve on admissions committees, I read around 150 applications, so I'll spend 3 to 5 minutes per app and place each into one of three piles: {good, ok, bad}. Then I may tell faculty in the relevant research sub-field to take a closer look at some of them.

Final admissions decisions are made in very different ways depending on department norms and constraints, but that's all out of your control. No matter what, though, you want to end up in the 'good' pile!

What is a Ph.D. program application?

The first step toward getting into the 'good' pile is to understand what your application really is before writing it:

A Ph.D. program application is a request for someone to invest around $500,000 and five years of mentorship time so that you can produce new knowledge via research publications. The exact economic details vary by department and institution, but the general idea remains.

When evaluating applications, I ask myself: Do I feel good about letting myself or one of my colleagues invest in this person – both in money and in time? The role of your application is to convince me to enthusiastically answer YES!!!

Concretely, this means your application needs to show me that you have either already produced research publications in your chosen sub-field, or that you have the potential to do so in the near future. Everything else is secondary.

The most important criteria: Research Density

In my experience, the property that best separates good from bad applications is research density. As the name implies, a research-dense application is one that is densely-packed with research-related content. The strongest applications are usually the most research-dense.

What this means is that the majority of your statement of purpose should be about research – not your childhood inspirations, not your personal intellectual journey, not your classes, and not your extracurricular activities. A common kind of weak statement is one that spends too much time describing the applicant's childhood; in general, avoid mentioning anything before college.

I often read weak statements that are way way way too long and not research-dense enough. Strive to write the shortest and more research-dense statement that you can.

This idea of research density also means that you need to find people who can write research-dense recommendation letters for you. For example, a letter about you doing well in a class is not compelling, since it has zero research density. A letter from a non-research-related job also has zero research density. All else equal, applicants with more research-dense letters will win. So choose your letter writers carefully.

How do I review Ph.D. applications?

The people who review Ph.D. program applications are professors like me, not professional admissions counselors. Some of them will be knowledgeable about your research area, and some won't.

Here's how I spend my 3 to 5 minutes evaluating each part of the app, roughly in this order:

  1. C.V. / resume (30 seconds max.)
    • Is it research-dense?
    • Is it not too long? I'd say 2 pages max, maybe 3. Don't fill up your C.V. with irrelevant details.
  2. Statement of purpose (1 minute max.)
    • Is it research-dense?
    • Is it not too long? My ideal is 1.5 to 2 pages.
    • How well do you understand what a Ph.D. application is? Re-read the prior section for details.
  3. Scores (30 seconds max.)
    • GPA: warning sign if too low, but usually don't care. It's rare that someone with strong research credentials has a dangerously low GPA, and even if that were the case, I wouldn't care much. A high GPA from a highly-selective university is a slight positive signal, though.
    • GRE: bad if really low, but otherwise don't care.
    • TOEFL: bad if below 100, but otherwise don't care.
  4. I'll reject here if the C.V. and statement aren't strong enough. Otherwise I'll move onto reading the letters ...
  5. Letters of recommendation (1 minute max. per letter)
    • Is it research-dense?
    • If a letter isn't about research, I'll skip it.
    • How long is it? Two-page letters are stronger than one-pagers. You can't control this, but you can control whether you pick someone who will write you a strong letter.
    • How much effort did they put into differentiating you from the hundreds of other applicants this year?

[Update in Dec 2020: I'm more busy now and we get more applications than ever ... so on my first pass I read only the letters and reject if they're not research-dense. Then if letters are good, I'll read Statement of Purpose. If all of that is good, then I'll more seriously consider the app.]

Final thoughts

If you create a research-dense application, that's the first step toward getting into the 'good' pile. You'll now be competing with tons of other applicants who also have research-dense applications, but at least you're still in the game.

The next most important thing is to choose a sub-field within the department that is most relevant to your prior experiences and to your letter writers' expertise (especially your primary letter writer who will write the strongest letter). For instance, if you've done the most significant undergrad research in sub-field X, mark down sub-field X in your app if you get to choose; that way, you will be placed in the same pool as others in sub-field X. And your app might get reviewed by faculty in X. If you choose your sub-field wrong, then you will be competing against students in another sub-field whose apps look stronger than yours because they have more prior work in that sub-field than you. (Some students did undergrad research in X but want to change to sub-field Y for their Ph.D. In those cases, I do NOT recommend listing Y. If you put Y down on your apps, then you will not look competitive at all since you don't have prior work in Y, and your letter writers are also not from Y.)

Even after you pick the best sub-field match for you, the next most important thing to work on is making your writing clear for professors who are not in your sub-field. Of the hundreds of apps I've seen, I'm not an expert in most of their research. Thus, it's crucial for you to show me why your research projects are important, what specific role you played in each one, what the main challenges were, and what the impact was – ideally a publication or steps toward one.

Finally, it's OK to cold-email professors whose research genuinely interest you – after you submit a research-dense application. Make sure to write a good email customized for them. We usually review applications in the month or two after the due date, so that's the best time to cold-email. At best, you get someone to notice you; and at worst, they'll just delete your email. (In the U.S., it is convention to refer to professors by "Professor [last name]", like "Professor Guo". This convention is likely different in other parts of the world, though.)

OK, five minutes are up; good luck!


[Updates in Dec 2020 ...

Random tips for Statement of Purpose:

  • Two pages at most (that's the convention in my field, at least).
  • Don't use tiny fonts. The faculty reading your app are a few decades older than you, and our eyesights get worse with age.
  • Don't use tiny margins. Stick with 1-inch or a bit smaller than 1-inch.
  • Single-space, not double-space; double-space makes it look like an amateur class report.
  • Don't cite a bunch of papers that aren't your own; that just takes up space. Cite only your OWN papers, and bold your name in the authors list.

Also I've noticed a trend lately of Ph.D. apps adding more supplemental questions. My advice is not to stress about those since your Statement of Purpose is far more important. Just don't write anything in supplemental questions that could be interpreted as a negative signal and you'll be OK. You won't ever get into a Ph.D. program due to supplemental questions, but it can hurt your app if what you write reflects negatively on you.

Random tips for interviews:

Back in my day (the stone age) students would get admitted without interviews, but nowadays the bar is a lot higher, so interviews seem to be a standard part of the process. My only advice is to PREPARE A LOT. It might seem like professors just want to casually chat with you about your research (“hey can we find a time to chat? lemme know, k?”), but trust me, it is 100% an interview. They are interviewing the top few candidates and deciding who to make offers to. All else being equal, if you prepare more than your peers, then you'll have an advantage; simple as that. Here are some ways to prepare:

  • First off, know every facet of your resume, application statement, and publications inside-and-out. If you can't even answer questions about what you worked on, then you're toast.
  • Learn about the broader implications of your research beyond the specific implementation tasks you did on it. Professors understand that many undergrads participate only in limited ways in research, but even if you didn't get to direct the high-level course of your project, you should still know the context surrounding it. That shows you have potential as a researcher, not just as a technician.
  • Read through a few recent papers from each professor you're interviewing with, especially those that relate to your own work. Professors will usually have lots of papers on their CV, so pick some of the most recent ones (since it's the freshest on their minds) and also try to pick those where they are the last author rather than a middle author (since that likely indicates it's their own lab's papers rather than an external collaboration). Exact authorship conventions vary by field, so use your judgment here. Basically you want to pick papers that they really care about, not those from secondary outside collaborations.
  • If you can watch recent talks or other videos by the professors you're interviewing with, that will both tell you about their research (good!) and, more critically, give you a sense of how their vibe is (e.g., their tone of voice, mannerisms, and general style) so you won't be caught by surprise when you speak with them.
  • Always write a polite and enthusiastic follow-up email after each interview.


Created: 2016-12-09
Last modified: 2020-12-16