While pursuing a PhD in an experimental field, one usually researches a given topic and conducts experiments that are rather closely related to this topic and one another. I imagine this specialization can be beneficial as one attains expertise in the research field and can work in a timely and focused manner.

However, I can also imagine that this specialization may make changing your area of research more difficult when applying for positions as a post-doc. Therefore, I am wondering about the advantages and disadvantages of researching scientific questions one is interested in, but that are irrelevant to ones PhD thesis on the side.

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    In more theoretical areas, the answer is "Obviously!" But since you're asking specifically about experimental fields, I hesitate to write that as an answer.
    – JeffE
    Sep 24, 2012 at 21:28
  • Even in experimental fields, you still need to branch out and explore different experimental paradigms/approaches/methods. Because, as a researcher, at some point, you will have to design new experiments or change/improve the current experimental paradigms/approaches/methods, and then you really need not just depth but also breadth. Dec 31, 2017 at 15:01

5 Answers 5


The main downside is that it takes a significant amount of effort to gain enough specialization in a given topic to be proficient enough to perform useful experimentation. Given that a a graduate student you're spending almost all your time familiarizing yourself with the topic you're actually performing research on, it would be very difficult to become an expert in an area unrelated to your work.

That being said, many research topics are very conducive to multi-disciplinary research. To use myself as an example, I usually tell people that I'm a cross between a neuroscientist, behavioral psychologist, signal processing engineer, and statistician. A colleague of mine started his research examining how to use the lungs as a power source for an implantable device, and ended up publishing a significant paper in the field of organic chemistry, fairly unrelated to his intended research. Becoming an expert in your own field enables you to research some pretty interesting and diverse topics.


The main downside is the opportunity cost of time spent being "unfocused".

Accordingly, I think the relative merit of pursuing ancillary research topics hinges on how much time you want to spend on your PhD. The road to tenure is long and so there are strong arguments for starting on it early. A PhD is just the beginning. However, later on, I do not think one can drop a side-project with as few consequences as during graduate school.

You should also distinguish between the same research that goes by different labels. Different fields call the same thing different names, which can make it seem as if someone has more varied interests than they do.

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    However, later on, I do not think one can drop a side-project with as few consequences as during graduate school. — Really? Why not? (I'm assuming that once a project attracts enough money to employs RAs, it's no longer a "side project".) How could faculty explore new research areas without doing exploratory side projects?
    – JeffE
    Sep 24, 2012 at 21:26
  • I see your point that my use of 'side-project' has a shifting definition. Perhaps its better to say that there is a bigger loss if you sink money, RAs, etc into a project that doesn't pan out as opposed to if you as a grad student wasted a lot of hours on something. Then, my comment just the time of someone with more experience can be worth more.
    – mac389
    Sep 24, 2012 at 22:01
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    @JeffE - Because later on, instead of just having time to play around doing research, you're writing grants, teaching courses, performing departmental administrative duties, and mentoring grad student & postdocs. Compare this to being a grad student, when your responsibilities include (1) showing up and (2) doing research.
    – eykanal
    Sep 25, 2012 at 2:47
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    @eykanal — Right. But playing around with half-baked crazy ideas that may not pan out is a prerequisite for writing good grant proposals, which is how we get grants, without which we have neither students nor postdocs. Side projects aren't a distraction for research faculty; they're a requirement. Departmental administrative duties, on the other hand...
    – JeffE
    Sep 25, 2012 at 5:21

I can see pros and cons to this. The pros are obvious and are just like you state: you will be gaining specific expertise, you'll be doing truly independent research , you'll be pioneering.

I would point out one major con though: if you do work that none of your professors are "in charge" of there is a good chance they will act like little babies and discredit, ignore, or openly assault your work! It happened to me.

I had my master's thesis in Scientific Visualization, which was an already funded idea hosted by my advisor. Unfortunately it wasn't a very popular idea so a) it wasn't that interesting, and b) I couldn't get much attention from my advisor. But then my friend, who was doing research in Computational Biology came up with a really great idea for a collaborative visualization project and I started working on that in parallel. It turned out to be really cool, I got a poster accepted to a major conference, and my friend actually benefitted from the output.

My advisor, however, was just pissed off. He didn't give a shit that I was doing my own creative work. He just saw that I wasn't playing his game. I actually got in trouble for this. I tried to appeal to my team of 3 professors who were my secondary advisors but they reamed me too. One of them said "well none of us know if your work is actually quality. Anyone can get a poster published." Mind you out of the entire group of 12 students who submitted work to the conference only 3 posters were chosen and two of them were mine.

So the short of it is: academics are like little boys tied to their mother's apron strings. Don't expect them to support you in being truly creative. If you follow this path then make sure you either convince a professor that it was his

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    Don't walk. Run. (We profs aren't all spoiled brats. Honest!)
    – JeffE
    Sep 24, 2012 at 21:13
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    Seems like a required primary goal was replaced by an optional, personal secondary goal, for whatever reason. But the question is about keeping primary as primary itself, a disciplined approach. +1 to @JeffE Sep 25, 2012 at 1:01
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    Boy reading this after a few years and man did I have a charge! @JeffE, a few years will cool ones head off a bit, I trust that all professors aren't that bad. Noble, I actually completed both projects, though to be fair my focus was mostly on the secondary project. Jan 25, 2016 at 4:03
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    Not to mention the irony that I'm exploding in rage as I call other people babies! Oh man... Jan 25, 2016 at 4:32

TLDR: You will probably become a better problem solver if you do it, but there is a chance that it won't count into the formal requirements for graduation!

In general I would say it is not a good idea to research multiple independent topics when you are a PhD candidate, especially if your PhD is supposed to be really narrow. The risk is that you will become distracted from the main focus of your project. Your main focus will then suffer and even if you actually do find results in the topics too far away from the project you are part of those are likely to be judged to not fit the project. Those results may impress other people for example in various industries and maybe academics too, but maybe they will not help you pass the formal requirements for graduation!

( Everything I've written is assuming you value graduation above all else, of course. )


I did several unrelated projects during my PhD. Here are my thoughts: You need to publish in order to graduate and find good postdoc opportunities. So if you have three unrelated projects/collaborations, but all close to publication stage, then just plan your time wisely and go for it.

Otherwise, if you have several unrelated projects, that are super cool, but you have different PIs guiding it, and it's all in the troubleshooting/design stage, you have set yourself for a 7+ PhD gig. You will need to report to each PI, show good progress, all while switching rapidly between projects. All doable and rewarding, but in the end, you will need to publish them, and its gonna be hard.

Another detail to consider is if your committee will require your dissertation chapters to form one cohesive story. Some departments require it, in which case you can end up with a lot of data you cannot use in your thesis.

So in retrospect, I wish my "eyes were not bigger than my stomach", but I did have fun doing the other projects, and I found what I want to do for my postdoc through trying different things. I am finishing in my 5th year with 3 publications, but so burned out :(.

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