Choosing the right lab for graduate school can be a daunting prospect. There are so many issues to consider. So many things that could go wrong. And you have to join the most prestigious lab you can get into, don’t you? Well, let’s consider for a moment what the main point of graduate school is. Graduate school is the time when you transition from being a student to being an independent scientist. It is primarily an educational experience. While in graduate school, you should pick up some subject-matter knowledge in your field. You should become familiar with the most important experimental or computational tools of your trade. You should learn how to choose scientific questions and how to solve them. You should develop general life skills such as how to communicate, how to work with other people, and how to get stuff done on time and to spec. So how do you find the right lab in which to acquire all these skills?
I think that the most important overall consideration should be whether you feel comfortable with the PI, the other members of the lab, and the overall lab culture. In my mind, this is even more important than the specific research area the lab works in. Graduate school will usually take about five years, and it is an important time in your personal development. The people you meet in graduate school will likely remain colleagues and friends for the rest of your life. If you're miserable the whole time, it's going to be an awful experience. And even if you manage to power through the misery, you won't have performed at your best. You could have done better elsewhere.
Further, even in the best-case scenario, you can expect that something is going to happen over these five years that will challenge you or bring you down. Maybe a close friend or relative will die. Maybe you’ll experience a prolonged period of illness. Maybe you’ll get pregnant. Maybe you’ll go through a bad relationship breakup. Maybe you’ll just be generally disenchanted with science or with your project in particular. Maybe you’ll feel that you’re not getting enough done and that everybody else is progressing so much more quickly than you are. Whatever it’s going to be in your case, you can be certain that something is going to come your way. And when it happens, being in a lab that is supportive, helpful, and pleasant can make all the difference between a successful PhD and a premature termination.
But what about building a competitive cv? Shouldn’t you go with the most famous lab, so you’ll get great publications and will be set for your future career in academia? I’m not convinced. If you've read my earlier post, you know that I believe all that matters career wise is that your cv is strong enough by the time you graduate that you'll get the next job on your career path. If you're on the academic track, that will usually mean 2-3 high-quality first-author publications, plus maybe a few more papers where you’ve made smaller contributions. In this context, "high-quality publications" means solid papers in recognized journals in your field. It does not mean Nature, Science, Cell, or PNAS. (While those won't hurt, they're generally not needed to get a good postdoc.) If you're not on the academic track, the requirements aren't that different. They aren't stricter for sure, so for the purpose of choosing the right graduate program and lab it's probably best to just pretend you're on the academic track. So, if the main goal is 2-3 high-quality first-author publications, this is totally achievable in many labs all around the world. Even in labs that aren’t that well known, in universities that aren’t that highly ranked, students routinely perform at this level.
Consequently, don’t obsess too much about the prestige of the university. Prestige is overrated at the graduate level. (It is much more important at the postdoc level.) Even the most prestigious labs in the most prestigious places frequently hire postdocs from all sorts of universities. This happens because the prestigious labs tend to employ many postdocs, often many more than they produce graduate students, and therefore they simply cannot fill all their positions with graduates from comparably prestigious labs. As long as you graduate with a competitive cv (see above), you’ll most likely be fine and get a good postdoc position. My personal opinion is that any university within the top 200 of the world university rankings will probably be just fine for graduate school. I got my PhD from a university ranked somewhere past 300, and I still managed to get a good job, at a university that is consistently ranked in the top 40 worldwide and in the top 10 nationwide in my field. I’m not saying here that getting a PhD from a higher ranked institution won’t help you. I just think that it’s not as important as you may think it is.
Related to this issue, I would like to emphasize that choosing a lab for graduate school requires very different considerations than choosing a lab for a postdoc. My advice in this post is specifically for graduate students; I may write an article for postdocs at a later date. Some labs are really good for graduate students but not that great for postdocs. Some labs are the other way round. Some labs are great for everybody, but those are much rarer and may be highly competitive.
In particular, I would be wary of very large labs that are staffed primarily with postdocs and senior scientists. In such labs, it’s not uncommon for graduate students to be treated as second-class citizens that need to fend for themselves. If you’re in that kind of a lab, you may rarely see your PI. Your day-to-day supervision—if there is any—is likely going to come from a postdoc. At that point, you may be getting worse supervision than you would have gotten had you gone with an inexperienced, first-year faculty member.
All else being equal, I would urge you to choose the lab that publishes more. If you're in a lab that publishes a lot, chances are you're going to be publishing a lot as well. By contrast, if you're in a lab that publishes rarely, don’t expect to see your name in print that often. In fact, it's not uncommon for a weaker student in a very productive lab to build a better track record than a stronger student might do in a lab that doesn't like to commit words to print.
Should you go with a junior faculty member or with a more established person? There are arguments for either route. If you go with a junior faculty member, you are more likely to get a lot of personal attention. You have the chance to build a lab from the ground up and to get your name on that lab’s important early papers. Most of the early students of scientists who became famous rose to fame with them. Of course, the early students of scientists who didn’t become famous didn’t, so take that for what it’s worth. The argument for an older, more established person is that that person is more of a known quantity. You can evaluate that person’s productivity, impact on the field, mentoring philosophy, and lab culture. The older adviser is also more likely to have connections that may be beneficial to you, and he/she is less likely to make rookie mistakes. Finally, a younger adviser might end up competing with you if you turn out to be really good. By the same token, an older, very established adviser may suck up much of the available grant money in an entire field. Once you leave the lab, you will have to change field and/or develop a clearly unique and distinct identity to remain competitive.
Some people worry about joining a younger professor’s lab since he or she might not get tenure. I don’t think this risk is particularly high, unless you’re at a school known for never giving tenure. Of course, be careful if the writing is on the wall and there are rumors that the person whose lab you’re considering may not get tenure. In all other cases, I wouldn’t worry much about the tenure situation. Also, keep in mind that if you go with a famous and established tenured professor it’s not certain either that they will stay for five years at the same place. They might get hired away while you’re in graduate school, and that experience could be almost as stressful as your professor not getting tenure. So don't decide against a lab out of fear, decide for the lab that overall seems to be the best fit for you. If that turns out to be the lab of an old, established professor, you’ll likely be fine. And if it is the lab of a junior person, you’ll likely be fine as well.
Finally, you need to be aware that there are generally two types of graduate programs: those that have a rotation system and those that don’t. If there is a rotation system, you rotate with 2-4 labs in your first year, and then you decide in which lab to pursue your PhD work. If there is not, then you get accepted into the program under the assumption that you’ll join a specific lab. The advantage of the rotation system is that you can test-drive a lab before joining. The disadvantage is that if none of the rotations work out, or if you don’t get rotation spots in your preferred labs, you may end up in a lab you don’t like or in no lab at all. If there’s no rotation system, then you have to decide on a lab without really knowing much about it. In the latter types of programs, you can set up your own rotation system of sorts by asking to be co-advised by two or three faculty members. After about a year, you can then decide whether you want to stay in the co-advised situation or whether you’d rather just work with one particular faculty member.
Ultimately, I don’t think it matters too much whether you join a program with a rotation system or not. Either way, I would encourage you to get to know the labs in the program ahead of time, and to only join a graduate program if multiple participating labs look attractive to you. Regardless of how wisely you choose your initial lab, you may reach a point where you have to switch, and at that point it’s good to have alternative options.