An interview with a Google HR person was brought to my attention. Apart from the fact that Google dehumanises their employees by calling this area "People Operations", the following quote was interesting:
On the hiring side, we found that brainteasers are a complete waste of time. How many golf balls can you fit into an airplane? How many gas stations in Manhattan? A complete waste of time. They don’t predict anything. They serve primarily to make the interviewer feel smart.
This seems fairly obvious to me, but technical candidates will probably have to live with this bankrupt assessment method for a while yet.
I have done my fair share of interviewing; I am not an HR professional, but I am often called upon to assess the technical side of candidates. I'm fairly happy with my hit rate, and since it is quite simple I will share some of it here. It's worth noting, this probably only works for vacancies up to intermediate levels of technical depth. It worked well for me at Ramboll Informatik, it worked well for KMD, it worked well during my time with the Grameen Foundation and with IT Synergy. I don't think it will work well if you're hiring for a position requiring a very vertical and deep skillset.
When speaking with the candidate, I rarely take more than fifteen to twenty minutes. This is partially because there's a lot of other non-technical people who want their slots in the interview process (sigh); it's also because it doesn't take a long time to spot a candidate who has the right mindset.
Mindset over CV.
Since fifteen minutes isn't a long time, I can't waste time on questions like "how long have you programmed in C#" or "what kind of classes did you do at university". And since every single job description ever written comprehensively fails to describe the job in any meaningful fashion, it's a safer bet to hire someone who can do the job described but who won't break down if it turns out that the new DBA hire also needs to know how to tune hardware.
A simple approach to interviewing doesn't deserve a long blog post. I ask questions which reveal the professional inquisitiveness characteristic of problem solvers. The questions are mostly freeform, and they do not require paper and pencil. The questions are hard to impossible to prepare for, and in most cases the specifics of the candidate's answer matter less than the way the answer is delivered. How long the answer is, the degree of animation, articulation of clear opinions.
Here are some of the questions I ask. I have annotated the first few to illustrate intent.
A little practical note: this is a list I accumulated over a period of time. I do not ask all of these questions in one interview; there is usually only time for 3 or 4 in one fifteen minute slot. But that is often enough; at least at the level at which I have had experience conducting technical skill assessments.