To PhD applicants: A word about department rankings
When I was applying for my PhD, I used rankings of computer science departments to help me decide where to apply. Rankings are never perfect, but I didn’t have access to detailed knowledge of the research landscape, and the rankings helped to steer me in the right direction. In retrospect, I can see that the rankings were not perfect, and I made one or two silly mistakes about where to apply, but I would have made even more silly mistakes without them.
I’m saying this to give you this context: I’m not anti-ranking. Very possibly rankings have had a negative effect on higher education overall, but they can be useful if done right, and if you read them in the right way.
The Computing Research Association has just released a statement urging everyone to ignore the new rankings of global computer science departments from US News and World Report. I’m sorry to see this, because I found the US News rankings helpful when I was an undergraduate. But I’ve read the new US News rankings, and I have to agree with the CRA.
These US News rankings are absurd. They are garbage. No one should read them, and I won’t even link to them. You can find them easily via a search engine. Please don’t. The ranking methodology is flawed, for a simple reason that any computer science researcher could tell them immediately. And we did. Influential researchers in computer science pointed out the flaws directly to editors at US News; they were ignored. I don’t know why the editors of US News would ignore this feedback, unless they cared a lot about creating a controversy that would generate page views, and not at all about helping students who are applying for their PhD.
I’ll repeat: Please do not read these rankings at all, not even if you intend take my advice and ignore them. If you click on them, even to laugh at them, you are spending advertisers’ money to support this magazine in misleading PhD applicants who are not as well informed as you.
My advice: If you need rankings, instead go to CSRankings.org. This is a fully open ranking from Prof Emery Berger at UMass Amherst that ranks global computer science departments directly by the amount of research they produce. You can filter the rankings by geographic area and research area. No ranking is perfect, but this is defensible and open.
I mentioned that rankings are only useful if you read them correctly. Here are some thoughts about how to do that:
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Overall ranking is not the same as subject specific ranking. The department ranked #50 isn’t ranked that way because its research is #50 in every area of CS. Instead, it will have some research areas that are #50 — which is still pretty damn good — but a few groups that are in the top five. If you are in one of those top groups, then you are in a top group, with all the same excitement and opportunity as the top groups at a bigger name school.
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Disregard small differences in ranking. Ranking is an ill-defined problem, so you can’t take small differences seriously. As far as overall strength goes, the school ranked #1 is exactly the same as the school ranked #5. Exactly the same. But #1 is going to be overall stronger than #18.
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For your PhD, what matters most is your supervisor and their group, rather than the department overall. This relates to what I said above, and is probably worth a blog post of its own.
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Rankings are not life. The distinctions that we are talking about here are small distinctions at the very top. The school ranked #100 — I haven’t looked up what it is — is a fine university with brilliant researchers where you will learn a lot. Here’s an analogy. The weakest football player in the English Premier League, who spends most of his time on the bench, is still a prodigiously talented football player who would run circles around anyone who you and I have ever met. The difference between Lionel Messi and that guy — that’s the level of difference we’re talking about here.
The key point: Use rankings as a way to discover departments you didn’t know about that are strong in your area. Don’t use them as a way to decide between departments: For that, you should be reading the work of potential supervisors that interest you. Doing a PhD is about learning to do research. What types of papers do you want to write?