Acknowledge When You Don’t Know Something

A big part of being a good researcher is recognizing when you don’t know the answer to something, and a likewise a big part of your PhD milestones (quals, proposal, and defense) will involve testing this. I’ve spoken with several professors and other students about this, and it is considered a universally important subject to these PhD milestones— your committee will test whether or not you know what you don’t know, and have the strength to admit that.

Areas You May Be Pressed

Your committee will likely try to back you into a corner where you don’t know the answer to something, usually in an area that you should be the right person to answer the question. Whether it is some obscure model or technique you haven’t heard of, some hypothetical about how your work would apply to new datasets or domains, or questions about fundamentals in math that you haven’t brushed up on, your committee will likely search for (and find) things that you don’t know. And they will know that you don’t know. If there is one thing professors are good at, it’s sniffing out bull-shitting students.

Responding If You Don’t Know Something

It is okay to not know everything and the right thing to do is to admit and acknowledge it. You can (and maybe should) speculate about what might happen if your model were applied to a new dataset, but you should make it clear that this is speculation and you would need to do the actual research to know for sure. If you really haven’t heard of something you feel like they expect you to know, you can respectfully apologize for not having heard of it, and ask for more information on where you can learn about it. If you are being asked to compare your work to something else you haven’t heard of or read, offer to brush up on the other papers and then follow-up offline. Or again, speculate on how the related work might compare, based on what you know about how it works vs. how your technique works. But if you haven’t run the experiments, do not make claims that you cannot support with evidence.

Summary

Most committees try to get students to admit that they don’t know something. Failure to do so will reflect poorly on you. You shouldn’t proactively try to not know something, or fail to prepare adequately because you can just be honest and say you don’t know. But at the same time, don’t back down or be afraid if you don’t know the answer immediately. Your committee expects this, and they want to make sure that you know it and can handle it professionally. Be confident, be factual and correct, and you’ll do great!