I’ve hired people in different capacities for most of my working life. As a founder and CEO, as someone charged with building new teams, as someone asked to support the hiring efforts in another team… I believe I never got the science completely right but developed somewhat of a gut feel and a tool chest filled with questions and techniques which worked for me.
One of the common issues I see in hiring is that interviewers ask hypothetical questions: You ask the candidate how he would solve problem x (often a problem in your organization). I believe pretty much all that tells you is how capable the candidate is in making stuff up. It says nothing about their ability to actually do the work.
Personally I always asked a potential hire to walk me through a project which went wrong. I ask them to walk me through all the gory details and ask tons of questions. When the candidate says “we” I ask what her personal involvement was. When she talks about something in the abstract I ask her to go into the concrete details of the situation. When she talks strategy I ask for tactics.
Nothing predicts future behavior better than past behavior (in an interview situation).
My good friend and kick-ass CEO Jana Eggers likes to ask “Tell me about your last project. Who was involved and what was the biggest challenge?” — an excellent starting point for further exploration.