One other skill I am looking for during an interview is intellectual horsepower. This is probably the most controversial element of interviewing – for a kick, read How Would You Move Mount Fuji to learn more about the subject, and for a ton of great interview questions!
The basic argument against the puzzle question is that it’s generally an ah-hah question and doesn’t show whether a candidate can perform the work they’re being interviewed for. OK – I buy that… I could bring in a Nobel-winning primatologist and they’d probably crush my interview question but they’d be a terrible developer. However, when I’m hiring I’m not just interviewing for someone who can slap together a few DHTML objects… I’m looking for an engineer who can code, for sure, but who can pick apart problems and drive creative solutions to them. I’m not just looking for someone who can come in and code in Java today – I may need a low-level C++ driver written tomorrow or I may need someone who can build a replacement to a multi-million dollar line-of-business application. So you know, I agree—no problem question will allow a candidate to prove their coding ability. But I also need to see their problem-solving ability.
That having been said, there’s more than one way to evaluate what my former General Manager calls IHP. As a matter of fact, I quite often couch my question in a coding question. For instance, I may throw a quick and dirty pointer question at a candidate (to see the depth of their CS skills—and you’d be amazed at how few candidates can code with pointers… it’s a shame), and then I’ll follow it up with a question like “Design a tool which takes in two string arrays – one is a list of words, the other is a crossword puzzle—and evaluates whether all the words are in the puzzle.” That’s an engineering challenge – seems straightforward, but it’s actually a puzzle.
I am not afraid to throw the puzzle question at people either. Yes, most of them are ah-hah questions where there’s only one answer and you either get it or you don’t. I try to stay away from them, although I don’t mind them too much. Very much like my coding or testing question, I’m less concerned with candidates arriving at the answer and more concerned about them showing critical thinking abilities, the ability to step back and re-evaluate a solution, and a little bit of thinking outside of the box.
What are some sample questions? How Would You Move Mount Fuji is a great source for these. Some I like are the bridge over the chasm (four people need to get across the bridge, it’s dark, and you only have one flashlight—how fast can you get them all across?) or the miner stealing an ounce of gold for every pound. There are thousands of these questions though. And anyone who thinks they aren’t fair should know that I actually run them past my Boy Scouts and they can solve them (sometimes with a little hand-holding, I’ll admit – but these are 12-year old boys!).
In evaluating, be sure to avoid the emotional evaluation. Don’t be overjoyed or think the candidate is a hire just because she got the answer. Stop and think about HOW they got there. Did the candidate just stumble on the answer? Did they guess? Did they get there so fast that it’s obvious they knew the question in advance?
Look for critical skills. Can they break the problem down? Do they arrive at an initial answer, but then continue to probe looking for a more elegant solution? Are they organized in their approach? Are they cool under the pressure? (That’s a lot of it for me – I am looking for candidates who can tackle a tough problem—with a senior manager in the room.)
Test scores and higher ed grades are a good indicator, as well, of performance. Keep an eye out, though, for the brainiac with no common sense. You probably don’t want them unless you have some really deep experimental research type of effort (cryptography?).
In the end, I’m looking for a balanced candidate. A super-smart person with poor coding skills isn’t as helpful to me. A hard-working coder who can’t think his way out of any problem might help me short-term with the challenge I’m facing at the moment, but I’m not convinced they’re a good hire. They might make a great contractor, but I’m only looking to hire bright people who will grow with my challenges and needs.