There are actually a fair amount of scientific studies on good interview practices. The book "Becoming the Evidence-Based Manager" gives a nice summary of many

There are actually a fair amount of scientific studies on good interview practices. The book "Becoming the Evidence-Based Manager" gives a nice summary of many of them. I'll spoil a bit of the book though. Free form "coffee interviews" or lunch interviews are the worst possible types. They introduce a ton of bias into the process that's not related to job performance.