Should you do a PhD in science?

by newptcai3 min read5th May 202119 comments

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Career choice
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This article is also posted on my blog.

Update 2021-05-09: Upon checking data more carefully, I have revised the chances of becoming a professor in math.

The joke

A friend sent me an article titled Is Science a Pyramid Scheme? posted on viXra, an e-print archive. The abstract is as follows --

A grievance expressed by some PhD students and Postdocs is that science works like a pyramid scheme: Young scientists are encouraged to invest into building scientific careers although the chances at remaining in science are extremely slim. ... The super-prolific authors at the top of the pyramid ... are usually heads of large institutes with many subgroups and large numbers of PhD students, while the bottom of the pyramid is populated by PhD students and Postdocs ... A new index, the Ponzi factor, is proposed to quantify this phenomenon.

The author of the article is named as Charleeze P. Ponzi, which is also the name of the person who invented Ponzi scheme. Since it is unlikely that the ghost of Ponzi (died in 1949) who wrote the article, perhaps the article is meant to be a joke.

The fact

However, the author does have a point in saying that "the chances at remaining in science are extremely slim". Take mathematics as an example, according to American Mathematical Society's latest annual survey, during the 2017-2018 academic-year

In mathematical and statistical sciences, 1,960 PhDs were awarded by the responding departments ...

Meanwhile, during the same period, 985 tenure-track positions in mathematical science
were offered across USA, among which 775 positions were filled. However, among these positions, only 296 are from departments offering PhD degrees, i.e., from places where you are supposed to do a lot of research besides teaching. And these numbers have been relatively stable for years. Thus, roughly speaking, a math PhD student in USA has at most 40% chance of becoming a tenured professor, but only 15% chance if you also want do a lot of research besides teaching.

15% does not sounds too bad.
But I probably overestimated this number, since PhD of other majors, like myself who studied Computer Science, applies jobs in math departments. And PhD produced in other countries also compete for these positions.

These numbers only applies to USA. It is likely that in less affluent countries there are not as many positions. For example, when I applied a position in Sweden, there were around 40 applicants in total.

Moreover, the situation of the whole field of natural science may be bleaker. By one estimate, about 2.2% German PhD students in natural science become professors.

The conclusion

I used to joke to PhD students that they should strongly recommend their friends to not to do a PhD, because

  1. research is indeed hard;
  2. this reduces competitions they fill in future job market.

However, I do seriously think people should think twice before they apply for PhD positions. They must realise that it is unlikely they will become professors. So, before applying, instead of imagining themselves becoming the next Einstein, people should think very hard about how doing a PhD can help them getting jobs outside the academic. Otherwise, five years of hard work may lead to nowhere and the result can be devastating.

That being said, I think Sweden, where I did my postdoc, makes studying for a PhD less risky. First, in Sweden, university only accepts PhD students whose funding has been guaranteed for fives years. This protects students from running into financial difficulty when they are close to finish line. (When I studied in Canada, a fellow PhD student had to use GoFundMe to support himself during the last year of his study.)

Secondly, PhD students in Sweden earn about 30k SEK (3500 USD) per month, which is not much but enough to have a reasonably comfort life. Thus, for most of students I met in Sweden, graduate school is just a place where they can explore their intellectual interest without worrying about their financial situation. They enjoy their time and they get well-paid industry jobs in the end. For me, that does not seem to be a bad deal at all.

Maybe other countries can learn a bit from Sweden. And maybe you can consider doing a PhD there.

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In my research I have found Princeton graduate students experience higher rates of moderate to severe depression (21.99%-27.90%) and anxiety (24.53%-27.80%) compared to national averages (8.75% for depression, 5.1% for anxiety). We had over 900 respondents (~30% response rate), and used a difficulty to reach technique to check our results generalize to non-respondents, which most other studies of this kind do not do.

As a result, I am very confident PhD students are more depressed and anxious than the general population, and I am very hesitant to recommend doing a PhD.

Have you published your results?

We are writing up the paper now! We sampled in 2019 and 2020. We used the PHQ9 to measure to depression and the GAD7 to measure anxiety. Happy to answer any questions if you have :)

Oh, I am going to start advise undergrads on career choices soon. Many of them will want to go to graduate schools. So I would like to give them some cautions. Please let me know when your article comes out. Good luck with publishing it!

Interesting, thank you for sharing.

Do you have a take on how accurate the national average estimates are? In particular, I'd be interested in whether they were determined using a different methodology, and so perhaps one that will be biased toward "underreporting". Where as at first glance your methodology might seem to be biased toward "overreporting" (though idk to what extent you may have "corrected" for non-reponse bias, which would be one source of "overreporting").

The national averages were determined using the same measurement instruments we used, but they did not control for non-respondents the way we did. My intuition is that the national averages are pretty accurate because they had big sample sizes and did not seem to be obviously sampling from a more depressed/anxious segment of the population. 

But you can decide for yourself:  

In a national sample collected by the National Health and Nutrition Examination Survey (n = 31,366), 8.75% of people in the United States meet the criteria for moderate to severe depression. When restricting the national sample to only those with a college degree or above (n = 6,660), national rates of moderate or severe depression were much lower than what we found in our graduate student sample: 3.8%

In a national sample (n = 5,030), 5.1% of Americans met the criteria for moderate or severe anxiety on the same measure (Löwe et al., 2008).

We controlled for non-responders by keeping track of how many reminders it took subjects to respond to the survey, and checked to see whether the harder it was to get people to respond predicted their depression or anxiety scores. It did not. We also had such a high response rate (30%) that even if all of our non-respondents felt depression or anxiety at rates equal to national averages (unlikely), the graduate students would still be worse off on average. 

PhDs get a lot of negative hype these days, so much that I wonder if it is potentially underrated it as a viable career step. I am just coming out of a PhD programme in the UK, and while I didn't always enjoy my topic nor want to continue research in my field, I still think it is overall a positive experience. It is important to realize that most people starting PhDs are well aware of the low chances of becoming a professor, but luckily there are still many good career options outside academia (however I do think all the negative hype around academic careers probably means that it is also underrated relative to its true value). Some of the good aspects of (science) PhDs are:

- Lots of flexibility. You are basically guaranteed an income for ~4-5 years that you cannot lose no matter how poorly you do. While your supervisor certainly has some influence over what you do during this time, you are surprisingly free to work on what you want.
- High potential for growth. You get to experience just how difficult it is to become a world expert in something, albeit very niche, because most often you are the first to attempt your line of research. Learning about what has been done before in a field, how to find a viable approach, and how to overcome unexpected setbacks are very transferable skills.
- This is a bit more speculative, but I'd reckon that you have higher chances of landing an intellectually stimulating career with a PhD compared to a Master's degree, at least in fields where credentials matter. I'd also reckon that as a PhD plus a few years experience you are likely to get promoted to leadership positions faster.
- Many fields EAs care about (nuclear security, biosafety, AI etc.) are very science-heavy fields where having a PhD is useful. For example, with a Physics PhD it would be relatively easy to get a job in either of these, since your skillset is sufficiently adaptable to most analytic fields. 

It is hard for me to think of much advice that has gone worse for rationalists/EAs on average than 'Get a PHD'.  I know dozens of people in the community who spent at least some time in a PHD program. There is a huge amount of people expressing strong regret. A small number of people think their PHD went ok. Very few people think their PHD was a great and effective idea. Notably, I am only counting people who have already left grad school and had some time to reflect. 

The track record is incredibly bad in the community. The opportunity cost is extremely high. I very strongly urge people to reconsider. 

Another angle is that it is just a very unhealthy environment on average. Here is Ben Kuhn explaining the data:

First I looked for a bigger survey of graduate student depression and anxiety rates. It wasn’t too hard to find one, and the numbers were almost the same: 41% of graduate students had “moderate to severe” anxiety compared to 6% of the general population; 39% had moderate to severe depression compared to 6% of the general public.

Having talked to many people for multiple hours (>100) over the years about their career decisions, I share this assessment. 

To give a bit more context: I've specifically seen some ML PhDs work out fine, but feel like I've seen almost every other type of PhD work out badly, with my sense being that the person was not in a substantially better epistemic or career position after their PhD, especially compared to them having worked an industry job in the direction they would have liked to go into, or just independently writing blogposts. 

More than half of the PhDs I have heard of were aborted in the middle, with the person going through a major depressive period or something similar like it during it, and the levels of regret afterwards being quite high. 

ML PhDs seem somewhat better, in particular at places like CHAI where my sense is that people are working on stuff that's a lot more aligned with their goals. Though I think the track record is still pretty bad.

For the very specific point made at the beginning, I don't think most scientific fields are pyramid schemes, unless by pyramid scheme you mean anything where there's a lot more people at the bottom than the top and the top is more desirable than the bottom (Like I don't think large companies like Google are pyramid schemes, unless you really stretch the term).  

Words are made by man, but I guess (removing normative judgments) my understanding of a pyramid scheme is a situation where a) many people at the bottom want to be at the top, b)  the success of the people at the top is a direct result of contributions from people at the bottom, and c) most of the incentive for work for people at the bottom is the excess returns at the top.

In that regard, legal pyramid schemes include poker, some arts, and some humanities. Also (more archetypally) multilevel marketing etc. I can also sort of see a case for professional e-sports/gaming, though I think the case is much weaker than for poker. 

In contrast, undergrad education in STEM (eg chemistry or CS) and some of the social sciences is both directly useful and relevant signaling that prepares people for non-academic jobs. Depending on the subfield, this is often true for PhDs as well, though the case for postdocs might be lower.

Agreed; the problems of academia are not similar to those of a pyramid scheme.

I suspect 1/3 is a significant overestimate since US universities attract people who did their PhDs all across the world.

That's what I thought. I also have a vague sense that depending on one's goals a majority of US tenure track positions may not be great because they are at colleges that do little research and where one predominantly has to do teaching? Or are these not included in the numbers the OP gives / aren't called 'tenure-track positions'? (As is obvious by now I don't understand the US higher education system very well.)

The survey includes also teaching positions.

That is true. But since US is already producing so many PhD, I guess it’s unlikely that a very large portion of these positions are filled with foreign produced ones.

Mental health effects are the reason I stopped considering doing a PhD. This might be specific to economics, but here’s one study that surveyed Econ PhD students:

“We find that 18% of graduate students experience moderate or severe symptoms of depression and anxiety — more than three times the population average — and 11% report suicidal ideation in a two-week period. The average PhD student reports greater feelings of loneliness than does the average retired American. Only 26% of Economics students report feeling that their work is useful always or most of the time, compared with 70% of Economics faculty and 63% of the working age population.”

https://scholar.harvard.edu/bolotnyy/publications/graduate-student-mental-health-lessons-american-economics-departments

Then again, a one-in-three chance of tenure after graduation isn’t so bad! (I did an estimate of my own using sources I’ve long since forgotten and came to a similar conclusion for economics — my guess was that 33% to 50% of graduates at top 30 schools get tenure track roles, and most of those end up getting tenure.)

15% does not sounds too bad.

15% seems to me like very bad odds for a multi-year training program, especially given it doesn't count people who start a PhD program and then drop out.

See also http://www.shouldyouphd.com/