Interesting interview in the New York Times (In Head-Hunting, Big Data May Not Be Such a Big Deal) last week with Laszlo Bock, senior vice president of people operations at Google, in which he said that the ability to hire well is actually pretty random. Google did a study, looking at tens of thousands of interviews, and everyone who had done the interviews and what they scored the candidate, and how that person ultimately performed in their job. They found zero relationship. Bock said, "It’s a complete random mess, except for one guy who was highly predictive because he only interviewed people for a very specialized area, where he happened to be the world’s leading expert."
So, if your organisation is finding it challenging to hire the right people, it would seem you're not alone and there's no magic solution to the problem. However, Bock did go on to share that they'd found that brainteasers in interview were a complete waste of time and serve mainly to make the interviewer feel clever. Furthermore their data crunching revealed that there is no correlation between someone's grade average or test scores and their performance, except for new graduates where there is a slight correlation.
What can you go on then? Bock suggests that what works well is structured behavioral interviews, where you have consistent criteria for how you assess people. He says, "Behavioral interviewing also works — where you’re not giving someone a hypothetical, but you’re starting with a question like, “Give me an example of a time when you solved an analytically difficult problem.” The interesting thing about the behavioral interview is that when you ask somebody to speak to their own experience, and you drill into that, you get two kinds of information. One is you get to see how they actually interacted in a real-world situation, and the valuable “meta” information you get about the candidate is a sense of what they consider to be difficult."