Where did recently-hired N. American tenure-track asst. professors of ecology get their PhDs? (UPDATED with a second year’s worth of data!)

At lots of different places! For the details, read on.

Some social science fields are quite hierarchical when it comes to faculty hiring. There’s a widely-agreed ranking of graduate programs, which have a strong tendency to hire faculty only from programs of similar or higher rank. As we’ve discussed, there are some defensible reasons for that, but probably also bad reasons. The same is true for computer science, business, and history. For instance, in those three disciplines, the top 10 programs train >70% of all US tenure track faculty, and only about 10% of US faculty are hired at institutions ranked higher than the one from which they obtained their PhD.

Anecdotally, my impression has always been that academic hiring in ecology (and other life science fields) is much less hierarchical. That the name of the institution from which you received your PhD isn’t considered by search committees, and correlates only loosely or not at all with the many things that search committees do consider. But why rely on anecdotal impressions when you have data?

So I went back to my pretty darn extensive list of people who were hired as tenure-track asst. professors in ecology and allied fields at N. American colleges and universities in 2016-17 (or 2015-16 in a very few cases). I was able to identify where 157 of those newly-hired ecology faculty got their PhDs (having tried to identify every single one). I was interested in the following questions:

• Do the graduates of a few “top” ecology programs comprise a really disproportionate share of newly-hired ecology faculty? 
• Do “top” ecology programs exhibit a disproportionate tendency to hire faculty from other “top” programs?

The answer to my first question is “no”. Those 157 newly-hired ecology profs got their PhDs from 93 different institutions. Simpson’s index was only 0.017, meaning that if you picked two of those 157 people at random, there’s just a 1.7% chance they’d have PhDs from the same institution. The most common places from which those 157 newly-hired ecologists got their PhDs: UC Davis, Florida, and Hawaii-Manoa, each of which had just 6 PhD graduates in this dataset.*

UPDATE: 150 new hires into N. American tenure track ecology asst. professor positions advertised in 2017-18 got their PhDs from 95 different institutions, with no more than 7 from any one institution. So in case anyone was wondering, the 2016-17 data weren’t a fluke. Also, 13% of those 150 new hires got their PhDs outside the US, most commonly from Canada (5%). /end update

UPDATE #2: I’ve now ID’d a few more people and combined the data across both years. 321 recently hired N. American TT asst. profs in ecology got their PhDs from 147 different institutions. The most from any one institution were Georgia, Florida, and Colorado (10 each). /end UPDATE #2

Here are a couple of amusing ways to illustrate the diversity of places from which newly-hired N. American ecology profs got their PhDs. First, they’re more diverse than the tropical tree species in the 50 hectare plot on BCI, which has a Simpson’s index of 0.026. Second, as many people in my dataset got their PhDs from Harvard, Yale, Princeton, and Stanford combined as got their PhDs from the University of Northern British Columbia–namely, one person. 🙂

A bit of a hierarchy does show up if we shift focus to types of institutions rather than individual institutions. 71% (111) of those 157 people got their PhDs from R1 institutions.** The remainder mostly got their PhDs from either R2 institutions (12%) or non-US institutions (17%). Now, I don’t know what fraction of all recent-ish ecology PhD recipients got their PhDs from R1 institutions. It might be more than half, given that R1 institutions are a substantial percentage of all US PhD-granting institutions and that they tend to have larger graduate programs than other PhD-granting institutions. But I don’t think it’s as high as 71%. So I suspect people who got their PhDs from R1 institutions are somewhat over-represented among newly-hired ecology faculty, relative to their representation among recent-ish ecology PhD recipients. There could of course be various reasons for this, which I discuss a bit below. (Aside: note that that 71% does not include several people who got their PhDs from non-US institutions that are functionally-equivalent to R1s, such as Toronto, McGill, and UBC).

Narrowing a bit further, 45% (70) of those 157 newly-hired ecology profs got their PhDs from AAU universities. Those are 60 top US research universities, plus Toronto and McGill in Canada. I don’t know what fraction of all recent-ish ecology PhD recipients got their PhDs from AAU universities. But I suspect it’s less than 45% (though not way less). Especially since a few of the AAU universities have small or nonexistent PhD programs in ecology and allied fields like wildlife and fisheries.

I was also going to calculate the proportion who got their PhDs from top-ranked EEB programs according to the 2010 NRC rankings, but then I decided I really needed to get back to work. 🙂

There are various non-mutually-exclusive reasons why PhD recipients from R1 universities, or AAU universities, are probably a bit over-represented among recently-hired ecology faculty, relative to their frequency among all ecology PhD recipients. From having sat on search committees myself and talked to many people who have, I can tell you what’s not going on: it’s not that faculty search committees in ecology check which applicants got their PhDs from R1s. Rather, it’s presumably down to variation among institution types in their propensity to attract and graduate students with both the desire to go into faculty positions and the cv’s to be competitive for those positions. Survey data on the career plans of prospective and finishing graduate students would speak to some of this, and I know those data exist. But those surveys tend to classify grad students quite broadly (e.g., “biology”), and I can’t recall seeing any surveys with data broken down by institution type.

The answer to my second question is “no” as well. For instance, of the 63 N. American tenure-track ecology faculty positions at R1 universities for which I was able to identify where the person hired got his or her PhD, 68% got their PhDs from R1 universities. That’s basically the same as the 71% of R1 PhD-holders among all 157 recently-hired ecology faculty. And 14/20 (70%) of identified hires at bachelor’s institutions got their PhDs at R1s.***

UPDATE: Of the 41 ecology asst. profs hired in 2017-18 at R1 universities whose PhD uni I could identify, 80% got their PhDs at R1 universities. So, a bit higher than last year but not a significant difference given the sample sizes. Overall, over the past two years 73% of new ecology hires at R1s were people with PhDs from R1s. Similarly, in 2017-18 80% of the 25 new ecology hires at bachelor’s colleges whose PhD uni I could identify got their PhDs at R1s.

Even if you restrict attention to “top” N. American ecology programs, the answer to my second question is “no”. Now, there’s no “objective” way to decide which are the “top” ecology programs, but FWIW the 2010 NRC “S” rankings for EEB programs and 2018 US News & World Report rankings of “ecology/environment” programs both include Harvard, Princeton, Duke, Berkeley, UC Davis, Yale, Minnesota, UC Santa Barbara, Washington University, Columbia, and Oregon State in their top 21. I’m Canadian, so I’m going to include Toronto, McGill, and UBC on the list of “top” programs even though they weren’t eligible for the US-only NRC rankings. And I’m going to include Indiana, Michigan, Michigan State, Georgia, Texas, UC Irvine, and Wisconsin to bump up the sample size, and because Meghan would get mad at me if I didn’t include Michigan. 🙂 That list includes some places I think of as stronger in evolution than ecology and omits several programs on my own mental list of “top” N. American ecology programs. But whatever; the answer to this question doesn’t change no matter how you define “top” ecology programs. In total, in 2016-17 those 21 “top” programs hired 9 ecologists I was able to ID (1 at Duke, 1 at Berkeley, 1 at Minnesota, 1 at McGill, 2 at UBC, 3 at Michigan). Here’s where those 9 people got their PhDs: University of the West Indes, Girona, UC Santa Barbara, Simon Fraser, Calgary, Toronto, Georgia, Maryland, University of Chile. So, only 3/9 hires at 21 “top” ecology programs got their PhDs from those same 21 “top” programs. Ok, not a big sample, but sufficient to establish the point, I think.

Some of you are probably wondering if the answer would change if instead of looking at recently-hired faculty I looked at all faculty. To which, I don’t know, but offhand I doubt it would change all that much. For instance, I don’t think any of the 10ish ecologists in my department got their PhDs from the same place.

I’m sure there are a few exceptions. I wouldn’t be surprised if people with Ivy League PhDs, or who spent time as Harvard junior fellows, are overrepresented among Ivy League profs in ecology and allied fields (then again, maybe they’re not!). And there’s probably some odd department out there that hires a disproportionate number of its own PhD graduates.**** But the exceptions are just that–exceptions.

What did poll respondents think I would find?

Last week and earlier this week I did some unscientific polls on Twitter and here to see what people thought I would find. Obviously, the respondents aren’t a random sample of ecologists. But there are enough of them (e.g., 157 respondents to my poll here) that I think their collective opinions are worth talking about.

Overall, a substantial minority of poll respondents both here and on Twitter thought that recent N. American ecology faculty hiring is less diverse and more hierarchical than it actually is. 32% of respondents here incorrectly agreed with the statement that “most recently-hired N. American tenure track ecology faculty got their PhDs from a relatively small number of institutions.” And 44% incorrectly agreed with the statement that “recent N. American tenure-track ecology faculty hiring is strongly hierarchical, meaning that higher-ranking institutions rarely or never higher someone with a PhD from a lower-ranking institution“. Finally, 63% of respondents here, and 81% on Twitter, mistakenly thought that BCI trees are more diverse than the institutions from which recently-hired N. American TT ecologists got their PhDs. :-)*****

Conclusions

In conclusion, I find these data heartening and hope you do as well. As I said above, there are some defensible reasons why faculty hiring in some fields is extremely hierarchical. But I don’t think that’s a healthy state of affairs. It creates the possibly-justified, difficult-to-rebut impression that the entire field is run by a cabal of well-connected insiders. Personally, and speaking as someone who got his PhD from a fine program that nevertheless does not rank high on any list of “top” ecology programs, I’m glad to be in a field in which the place where you got your PhD has at most a modest correlation with your prospects for a faculty career.

*It is very much not the case that getting your ecology PhD from a top program like UC Davis more or less guarantees you a tenure-track faculty position if you want one. Which is in contrast to, say, economics, where a PhD from, e.g., Harvard or MIT does more or less guarantee you a faculty job. At least, that’s my understanding; happy to be corrected by anyone who knows better!

**See here if you don’t know what “R1” means. Roughly, it means “big US research university”. Think Harvard, Stanford, Michigan, Michigan State, etc. For “R2”, your search image is institutions like Wyoming, Maine, and Ball State.

***It is rare for bachlelor’s institutions to hire ecologists with PhDs from non-US institutions. I wouldn’t make too much of that because this dataset doesn’t include a huge number of hires at bachelor’s institutions, or a large number of non-US PhD recipients. But for what it’s worth, I suspect that trend is real and due mostly to self-selection on the part of non-US PhD recipients. I bet that most ecologists from outside the US who are prepared to take up faculty positions in the US are looking for positions at research universities, not teaching colleges. Teaching colleges might also be concerned about how well-prepared applicants with PhDs from outside the US are to teach US undergraduates (see here for a bit of discussion).

****In case you were wondering, none of the 157 people in my dataset were hired where they got their PhDs. Yes more evidence that ecology faculty positions are hardly ever filled by someone with a previous connection to the hiring institution.

*****On the blog I also polled people on what fraction of new hires got their PhDs from UC Davis, or Florida, or Hawaii-Manoa. But I phrased the question ambiguously, so that it sounded like I was asking for the total fraction of new hires who got their PhDs from any of those three places. Many answers missed high anyway, but I’m still just going to ignore this question.