A reader wonders whether it is a bad idea to do a postdoc in the same department/institution as the PhD (but in a different research group, with a different supervisor). This is an interesting question, and raises some related questions.
There are many possible combinations of staying and going in an academic career, from undergrad to postdoc and/or faculty position. I don't think it's worth making a distinction between those who do an MS and PhD at one or more institutions, as some departments require an MS along the way to the PhD, some don't require an MS at all, etc. Of course some people do get an MS and PhD at different institutions, but staying at one institution for an MS and PhD is not as significant as staying for some or all of the other stages of an academic career.
With that in mind, I would classify the extreme cases as:
case 1: different institution for every stage from undergraduate to faculty position (probably the most common, especially since those who go to undergrad institutions without grad programs have to move, by definition); and
case 2: two or more institutions the same for consecutive stages of undergrad, grad, postdoc, and/or faculty stages (most extreme case = all stages at one place).
I included the word consecutive in the second case because I think it is important to distinguish between those who return, perhaps many years later, to a former academic home and those who just stay.
I have seen diverging views of those who stayed in one place for undergrad-grad or grad-postdoc, from "S/he stayed at the same place because no one else wanted them" to "S/he is so awesome, University X didn't want them to leave".
I have also commonly seen in reference letters for undergrads applying to grad school, "I would gladly have accepted Z to stay on as my graduate student, but I know it is in his/her best interest to move on to another department." (implying that it is conventional wisdom that moving = better?).
As usual, I have lots of questions, and as usual, the most likely answer to most of them is "It depends..", but I think we can be a bit more specific than that, if only to make things more interesting. As usual, I hope that there will be many different points of view represented in the comments; e.g., from those who stayed, those who went, and those who are in a position to make decisions (e.g., hiring) about those who stayed vs. those who went.
Questions for discussion:
- Is case 1 always better than case 2? (my opinion: I think it is good to move if you have that flexibility, but case 2 is not by definition bad.)
- And if you think so, is case 2 necessarily bad, or just not as good? (my opinion: case 2 is not necessarily bad; in some cases it might even be a better career opportunity to stay, although probably in most cases it's not better. I guess we could debate what are good vs. bad reasons to stay in one place, and whether we think this has positive or negative consequences.)
- Does it matter which stages are involved? For example, undergrad and grad at the same institution is good (or bad), but grad to postdoc is bad (or good)? (my opinion: Above, I wrote about how many people think that it isn't in a student's best interest to stay from undergrad to grad, and I guess I have to agree with this. I have never wanted my best undergrads to stay on and work with me as grad students; I think they should move on. However, 'should' does not mean that I would be critical of someone who did this. I also think that the grad to postdoc situation is different, maybe even indicating something good about research momentum, ideas, independence, excellence etc.)
- If someone does stay at one institution -- for example, from PhD to postdoc, as in the case of the person who wrote to me with this question -- does your opinion about staying vs. going change if there is an internal change from one research group to another? (my opinion: I don't think it is a strike against someone to stay in their grad department as a postdoc, especially if it's a short-term postdoc and certainly not if the project and/or advisor changes. Perhaps the grad/postdoc-to-be got their own funding? It's good if you can move and want to move, but it's not dire if you don't.)
I think these are the situations of most interest. Postdoc-to-faculty at one institution is going to vary a lot in goodness or badness depending on whether the postdoc is largely an independent scientist who clearly deserves to be hired in a faculty position (= good), or whether that person is someone's favorite minion and they are hired in an inside-job political move (= bad).
I have moved around a lot in my career, and I'm glad I did that (and had the flexibility and opportunities to do so), but academia is not one-size-fits-all, and there is room for all sorts of career paths followed by many different people with many different priorities, preferences, and experiences.
For me, it was important to move on from time to time. I met many interesting people, gained new collaborators, and developed new research directions in each place. Perhaps you can do this as well in a very large and dynamic institution, and therefore perhaps the key to whether staying vs. going is good vs. bad depends on what you do with your opportunities in each place.