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2014 December 23

A long PhD is not a bad thing

In response to, where she argued in favor of 5-year PhDs, and producing many papers as a grad student, I commented

I spent 8 years on my PhD (of course, I changed fields from pure math to computer science to computer engineering in that time). I only had a few papers when I was done, but I was in a hot new field and got a tenure-track position immediately. Unfortunately, it was not a good fit, and I ended up moving to another institution after 4 years, where it took me 7 more years to get tenure. So my BS-to-tenure time was 19 years. (The second job was a good fit, and I’m still at that university, though in a different field and in a different department.)

I find it difficult to advise students to race through grad school or to write huge numbers of crappy papers. I think that it is more important for students (and researchers in general) to write one or two high-quality papers that might actually make a difference.

Of the papers I wrote in grad school, one has never been cited (probably only one other person ever read it), one is my 6th most-cited paper (350 citations in Google Scholar and 86,600 hits with Google), and one has had very modest citations (85). My thesis itself was one-year throwaway work (only cited 9 times).

Note: I had fellowships for most of grad school, so only worked as an RA for 2 quarters and a TA for one. The highly cited paper was one that was not the result of any funded project, but an idea that another fellowship student came up with on his homemade computer and that we played with for a few years. The idea made over $100,000 in license fees for the campus and is what got me into the hot field that I was later hired for. I think that a lot has been lost by pushing students to be “hands in the lab” for senior researchers.

I’ve been sitting on this comment since March, with the idea of turning it into a full blog post.  I’ve seen a lot of different attitudes on the part of both grad students and faculty about how long a PhD should take and how much should be done for it.

My personal take is that a PhD education should be both broad and deep—one should have enough breadth of knowledge to teach several different undergrad courses and enough depth in one subject to have contributed original work to the field.

Research faculty generally want students to stick around for a fairly long time, so that they get payback in terms of co-authored papers for investment they have made (usually with Federal money) in the students’ initial training. A lot of them see no value to breadth, though, and just want someone to do the tough work in their lab.  They want students to start in research labs right away and see any time spent in coursework as wasted. These faculty often value research much more highly than teaching, doing the bare minimum teaching that the university lets them get away with—they also don’t pursue further education themselves, not attending any research seminars unless the seminar topics are directly tied to their current research projects.  The students they turn out are often very narrow researchers—good in one field, but not adaptable to changes in technology or research funding fads. Although these faculty often have impressive research teams, I’m not impressed with them as professors, as they have too narrow a view of what the role entails—they should be working in a private or national research lab rather than as professors at a university.

A more balanced professorial view sees the role of grad students primarily as students, learning how to be researchers and teachers, rather than as hired hands in the research lab.  As students, they should be continually learning new things, not just getting lab results in a narrow specialty.

Some grad students want to get the PhD certification as quickly as possible with as little effort as possible.  They generally end up in jobs that don’t require a PhD, so I don’t know why they bother—they’d be better off in most cases getting an MS degree (which is much faster) and going to work in industry.

Other grad students end up getting in a rut: not making much progress on their research, not taking any classes, not working on other research projects—basically just marking time.

Others start many projects, but don’t bring any of them to the state of completion needed for a thesis (that was me as a grad student—always busy, always learning, but not wrapping things up). Both the students in a rut and the students flitting from project to project may need to have their funding cut off, to motivate them either to finish theses quickly or give up—my thesis was written in a year after I was told I had only one year of funding left.  I think that there is some benefit to letting productive students have a free rein for a while, though—forcing students into a narrow niche too soon results in narrow researchers.

Some students try to turn their PhD thesis into a life work—as if the thesis is the best thing they’ll ever do.  This is a serious mistake that results in their staying a grad student for much too long. The point of a PhD thesis is to get the student a PhD—it is to establish that the student is capable of original work that contributes to the field and of writing that work up, no more. My own thesis was basically a throw-away research product.  By the time I was done with it, I realized that it was the wrong approach for tackling the design problem.  The only interesting part was a cute NP-completeness proof for a routing problem, all in pictures, but that was a time when new NP-completeness results were basically unpublishable, so I never bothered publishing it anywhere other than my thesis.

Having students do original work is not enough—the check that students can write things up is an important one. I’ve seen more students fail to get PhDs because they couldn’t write up their work than because they couldn’t do the research—that is one reason why our advancement to candidacy requirement consists mostly of writing a long, detailed research proposal, essentially a first draft of the thesis.  Students who can’t write either need to get help or find a job that does not require as much writing as most jobs that require PhDs.  (Incidentally, the problem of writer’s block often hits hardest those students whose writing is the best, when they can get it out—the problem is often one of perfectionism. So the strategy for addressing the problem has to be primarily psychological, not just instruction in writing.)

In recent years there has been considerable pressure on universities to pump students through faster, at both the undergraduate and graduate level. The effect has often been to deny students the chance to explore things outside a very narrow field—once undergrads have completed major requirements and university-mandated general education, there is no time left for other interests (and general-education requirements rarely are satisfied by other interests—they are usually mandated to be a bunch of low-level courses distributed across the curriculum to ensure butts in seats for various departments). Grad school pressure to reduce time-to-degree has often resulted in reducing the coursework requirements and getting students into research labs sooner, again reducing the breadth of student education.

Personally, I like “honors” programs, where at least the top students get released from the rigid bureaucratic requirements of general education and are free to shape idiosyncratic programs that get breadth and depth by following multiple interests, rather than by taking large numbers of survey courses.  I had such a program as an undergrad (the Honors College at Michigan State) and my son is currently in such a program (the College of Creative Studies at UCSB). It may not work for all students, but it is a good way to handle the students who are actually interested in learning things, not just in getting a degree.

In addition to my math degree, as an undergraduate I took a variety of other courses, some of which were interesting, some of which turned out to be duds. As a grad student, I continued this practice, and some of the just-for-fun courses turned out to be crucial to my future success.  For example, the computer music class lead to my taking the VLSI design class, in order to make a single-chip implementation of the plucked-string algorithm that Alex Strong and I had developed.  I ended up teaching VLSI design for over a decade, and the plucked-string paper is my 6th most-cited paper (365 citations on Google Scholar). Neither the plucked-string algorithm nor the VLSI design would have happened if Alex and I had followed the more conventional route of joining a professor’s lab and working on the problems that professor was funded for.  I would have finished my degree sooner, but would have developed a much narrower view of what research is worthwhile.  Although I took a long time as a grad student and a long time as an assistant professor, I still made tenure when I was 38, which is (just barely) below the average age for scientists getting tenure (over 39 according to Physics Today).

My son plans currently to take a lot of courses in his major (computer science), in his other academic interests (math, maybe physics and linguistics, maybe computer engineering), and in his recreational interests (acting)—it looks like he’ll only be required to take one or two classes that are of no interest to him.  He has taken more time in his pre-college schooling than I did, so he’ll probably not get his BS until he is 22 (I finished mine at 19), but he probably won’t need as long in grad school as me, because he’ll have had more time and opportunity to explore his interests earlier. (I certainly wasn’t ready to found a company at age 18!) For that matter, he might decide to go into full-time engineering with just a BS, and not go the academic route at all—his entrepreneurial spirit is more like his uncle than like his father.

Perhaps he’ll do what a lot of the students I teach have done: work for several years (or decades) in industry, then come back to grad school when bored with that, wanting a more interesting challenge.  The re-entry grad students generally do not take a long time to the PhD, because they are focused on their research, though they don’t seem to be much better than other grad students on planning what comes after the PhD.


  1. This is one of those questions where it’s really impossible to have a catch-all answer. I actually agree with you, that a student should be able to explore widely rather than be chained to the bench/computer/whatever. But there are limits to “widely” when they are being paid on federal grants. A reasonable advisor will be able to make peace between the two. But sometimes the constraints that come with federal funding make it hard.

    A few weeks ago I had a meeting with a few of my fellow computational scientists on account of some inter-college initiative. It turned out I am the only one whose students get a MS in another discipline (that generally means 8 courses in another department). Everyone looked at me like I was crazy. Several shared that they didn’t want the students wasting their time, which they should devote to research.
    I understand their attitude, but I actually think, based on experiential evidence, that having the students do only one thing day in and day out for months actually hurts morale and productivity. My attitude is that when students are done with regular coursework, it is actually beneficial for them to take other classes in whatever they like as long as the load isn’t ominous, because it’s a release, it gives structure to their week, and actually helps productivity. For the same reason I have senior students TA a little if they have no coursework, because it helps with motivation to go out and talk to other students; undergrads are fun and generally good for lifting one’s spirits.

    On the other hand, I understand the pressure from the funding agencies. For example, I am up for renewal of a major grant. I received $500k for 3 years, so I asked what the expected productivity was. I am kind of in between two program managers. One said the expectation is a society-level paper per $100k (Glamour Magz cost more), which is reasonable and would result in 5 expected papers. Another said 3 papers per year, which would mean 9 papers! I have three students on that grant, that means every single one of them has to have a paper per year, which is possible near the end but not with newbie students. Yet, here we are. If I don’t pressure them, we don’t get renewed. Mostly, that means I work 24/7 to get the last 3 papers out by Feb 1, while my students are variously traveling for fun over the holidays.

    I don’t want to be a slave driver, but I totally understand where it comes from, so I have to say I don’t begrudge my colleagues too much. You bust your balls to get funding, and you want to keep it, which hinges on productivity. As long as the funding mechanisms for graduate students are what they are, we’ll be having people who want students to just work on research, because you literally cannot afford to have your students spend time acquiring breadth.

    Comment by xykademiqz — 2014 December 24 @ 10:40 | Reply

    • I agree that the current funding model for grad students, as workers on specific grants, is flawed. I’d like to see a lot more students on fellowships—NSF does give a fair number of fellowships (though I’d like to see that double, by transferring funds from some of the “big science” projects). NIH does a terrible job of supporting education—preferring to exploit the postdoc holding tank, rather than supporting grad students.

      Research should be judged by the quality of papers, not the quantity. I’d rather see a project produce one really seminal paper than 9 paper-wasters.

      Comment by gasstationwithoutpumps — 2014 December 24 @ 12:52 | Reply

      • I’d rather see a project produce one really seminal paper than 9 paper-wasters

        Well, sure, but it’s not either/or (either seminal or a paper-waster). Most people never do anything truly seminal, one can hardly expect every 3-year project to produce something of the kind. On the other hand, just because something isn’t seminal or doesn’t appear to be at the time of publication, that’s not a reason not to publish if it is serious and novel work that pushes the field along. Science moves forward between seminal discoveries by incremental efforts of many scientists. That’s how consensus is often built — many people gnaw on a problem from different angles and eventually they all agree on what holds and what doesn’t.

        Comment by xykademiqz — 2014 December 25 @ 12:55 | Reply

        • but it’s not either/or (either seminal or a paper-waster)

          Agreed, but program managers insisting on 3 papers a year are likely to result in paper wasters—quality has to be more important than quantity, but counting papers encourages generating least-publishable-unit papers, which don’t further science much and waste the time of both the writers and the readers.

          Comment by gasstationwithoutpumps — 2014 December 25 @ 13:17 | Reply

        • Still, completely true, but also not very practical. If you are a program manager, you evaluate on the timescales of a couple of months to at most a couple of years since the papers from a certain project appeared. You could be a) singularly knowledgeable in the area and decide for yourself how good the papers are or, more likely, b) not be particularly but only generally knowledgeable and thus rely on metrics such as where the papers are published and how many there are, thus hoping the peer review does what it’s supposed to do. Therefore, more papers in reputable venues is better than fewer, or fewer papers in extremely prominent journals. What happens 5-10 years down the road is another question, but many papers do live up (or down) to the journal impact factor in terms of how often they get cited per year in the few years after publication.

          Anyway, I don’t think I disagree with you on premises at all, but the reality of doing funded research and the relevant timescales results is many less-than-ideal situations.

          I personally would also like to see more fellowships and also longer, 5-year grants, so that I know a student will be funded throughout their PhD. Right now, I have to have two grants funded per student in order to keep them funded all the way through. While I have to say I enjoy the brainstorming, creative part of grant writing, so much time is spent on it that it hurts the very research they are supposed to fund and the students whom we are supposed to train… But it is what it is.

          Comment by xykademiqz — 2014 December 25 @ 21:47 | Reply

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