I went on a training course for people who interview other staff, and the key issue is that you've got to get them to tell stories.
Testing their competence is one thing, of course they should be able to prove their knowledge of Perl or whatever, but in order to get to know their personality and how they feel about work, you have to get them to tell a story about stuff they've worked on.
Did you ever work somewhere with tight deadlines? Talk to us about it.
Have you ever worked with a co-worker who you just couldn't stand? Tell us about it.
Have you ever disagreed strongly with a manager about the way a project was handled? Tell us about it, and so on.
That's why "what's the longest you've ever spent in front of a computer?" is a great question -- whatever the answer, there must be a story.
In reply to Re: Number 1 mistake to not avoid during an interview
by Cody Pendant