One of my employers ran candidates through a gauntlet, and required every interviewer to submit a list of the questions they usually asked, because ... at lots of outfits, everyone asks pretty much the same questions, and (stupidly) explains the answers, so candidates appear to get smarter as they move around.
Chatting about sports, or shampoo (actually happened to me) is a waste of time.
My personal guidelines for conducting a useful interview:
Ask questions. Sketch illustrations to go with them. Record the answers. Do not explain. Do not comment. Do not indicate if the given answers are correct or not. Customize a few questions to probe the candidate's claimed background.
[ Yes, it puts the candidate under a lot of stress. When you're working, you're under stress, and you don't have someone to explain the answers, or even the questions. You need peers who can survive in that environment, too. ]
As soon as the candidate departs, spend ten minutes writing down your impressions. File a polite, heavily edited version with HR. Be very cautious about making actionable statements.
Keep your record with sketches, answers, the date and the candidate's name. You may need it to defend yourself.
examples:
"Geez, why did you recommend we hire that girl as a receptionist; that's a sexist stereotype." "Granted, but she claimed to be a programmer, was interviewing for a programming position, and I couldn't induce her to pick up a pencil and write a simple program. She's not repulsive looking, doesn't smell bad, and speaks clearly. You put a question on the HR form asking what I'd hire her for if not for the putative position, and I answered it honestly. Remove the question from the form if you don't want it answered."
"Geez, why did you recommend that we not hire that girl?" "She claimed to be a nuclear engineer, so I asked her what a moderator does. She didn't have a clue. And she didn't do well on the general engineering questions I asked, either. Here are my notes.."
No, I don't have anything against women engineers; I know a couple whom I'd hire in a minute, for their brains. Those two were memorable because I was challenged about them, and they clearly had no qualifications beyond helping us meet some EEOC statistic.
Your mileage may vary.
Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA