Google doesn't even ask for GPA or test scores from candidates anymore, unless someone's a year or two out of school, because they don't correlate at all with success at the company. Even for new grads, the correlation is slight, the company has found. Bock has an excellent explanation about why those metrics don't mean much. "Academic environments are artificial environments. People who succeed there are sort of finely trained, they’re conditioned to succeed in that environment,".Exactly right. Graduating (and the difficulty of course - lots of math or science course for example tell you something about the students capability) tell you something about a person's ability to put up with a constraining system (which many jobs also have) but grades are not very valuable. And graduating just gives you a bit of data, people can have that same capability without graduating.
Google also used to be famous for posing impossibly difficult and punishing brain teasers during interviews. Things like "If the probability of observing a car in 30 minutes on a highway is 0.95, what is the probability of observing a car in 10 minutes (assuming constant default probability)?" Turns out those questions are"a complete waste of time," according to Bock. "They don’t predict anything. They serve primarily to make the interviewer feel smart."Dee Hock has some very good ideas on hiring: "Hire and promote first on the basis of integrity; second, motivation; third, capacity; fourth, understanding; fifth, knowledge; and last and least, experience." Related: Hiring the Right People for Your Company - Signs You Have a Great Job, or Not - Google’s Answer to Filling Jobs Is an Algorithm - Hiring: Silicon Valley Style - Interviewing and Hiring Programmers