Best Quora answer I’ve read on hiring. Via Yishan Wong, CEO of Reddit
You can’t do it in an interview setting. The interview process is mostly self-reporting and especially for the worst of the fakers, it’s about putting on a performance. You should be relatively suspicious about interviews.
The way to assess if someone is good at getting things done is to see what things they’ve gotten done. That is, have they gotten things done in a way that is dramatically above the baseline of what someone in their current career point should have? This is pretty straightforward to assess.
Most people you will be interviewing will be at least, say, 20 or so. That’s a low estimate, like if you are a startup trying to hire kids out of college or whatever. If you’re looking at college new grads or experienced candidates, they will be in their 20s or even older. By then, people who “get things done” have had ample opportunity to do just that, and they will be able to point to the results. Often, the best of those people started in their teen years, working on random projects and stuff – perhaps nothing of real import, but nonetheless demonstrating that in their case, idle hands and boredom result in productivity. After university schooling and a few jobs, these random projects will start to pile up – we are talking years here, and the differential between people who “get things done” and people who don’t starts to make itself apparent in obvious ways. So you ask them or stalk them, and find the answer to the question, “What stuff have you gotten done?”
You must remember to exclude all projects done under the aegis of a school assignment or workplace job. Those are the things that their peers get done, and you want to know what they have done above and beyond their peers. Anyone at the certain level of career experience will have gotten those things done – in fact, if they cite their school/work projects as examples, it’s probably a red flag because they don’t have anything else – those are things they had to get done. What you are looking for is the person who, in addition to their school/work projects, happened to – for their own personal reasons – decided to build or create something and brought it to a finished point. Repeatedly. People who do this leave evidence lying around all over the place. After all, they get things done – and done things end up sitting around so you, the future employer, can easily discover this evidence of an unusually productive person.
Find that evidence. If it doesn’t exist (and the person doesn’t uncover it for you – maybe they stick it all in a self-storage garage or something), then no matter how they perform on a behavioral interview, they don’t really get things done. I would say that almost 100% of everyone I’ve ever hired who ended up being unusually productive and drove projects to completion had a clear prior record of being someone who did tons of random projects in a very obvious way.