The issue that keeps amazing me is why entire academic systems are set up to have few large hierarchical groups as opposed to more smaller ones, even though I do not often hear arguments why large groups are better, not even in Europe. Usually, the only arguments are (a) it has always been like this, (b) why should it change? and (c) oh, but it is very nice to have a big group. The only more decent attempt was that a large group might favor risk taking, because the person in charge does not have much to lose if something fails. First, I’d like to see at least some attempt at data before I believe this effect, because the the most hierarchical setups do *not* appear to be the most creative ones. And second, this is a first-rate argument against joining a large group.

At the same time, however, if the lab group is too small and the research program underfunded, the training experience can also be a disaster. This is especially challenging for trainees working with new investigators. It is extremely important to do one’s homework when considering where to pursue one’s graduate research training, which can take half a decade or more.

How much individual attention did each postdoc get with Big Shot PI? The answer is zero. They communicated with him via email only (he was off-campus most of the time, busy running his biotech company).

I haven’t been aware of your third and fourth points being a major problem in any of my positions, although I agree that those are very real dangers.

I have a colleague (an experimentalist) who at a time had 25+ students and maybe 2 postdocs, and the group didn’t get more than 4 or 5 papers per year (they were so-so, not that you could say they were holding out for high impact stuff). The issue was that most of the students were completely unsupervised and were wasting time and money. The group imploded when the funding didn’t get continued, 2/3 of the students just got sacked. It’s really sad — all the time and money spent and nothing.

No doubt some (very organized and successful!) people are able to be crazy productive with large groups. But you hit the nail on the head with your insight that in such an entreprise the success of the PI and the group far outweigh the success (present or future) of any student or postdoc.

As for an optimal group size, it takes a bit to determine one’s own. It depends on one’s workstyle and environment (my tenure home is an engineering dept, so postdocs are not ubiquitous). For me, I am a bit on the high side right now in terms of personnel (1 postdoc, 8 grad students, 1 undergrad), and, since I want to meet each one of them every week individually and also have a weekly group meeting, this is a lot of meeting time… But is absolutely necessary to keep everyone productive. I had a time where all I had was 3 or 4 students and that was really not enough, but on the upside I still had the time to do the nitty-gritty techical work on my own (e.g. publish single author papers). I can’t do that with this group size, just the bandwidth require to handle the group’s output (not to mention raising funds!) is considerable.