> I continued to use [the interview question] because I got good signal from the candidates.
Working at Google, this is something I hear a lot: that some question, or other interview thing, is good for getting "signal" from candidates. But how do you actually know?
Like, I feel to definitely know a question is good you would actually need to track candidates after they start working and see if their performance on the question correlates with their job performance. (Unfortunately, it seems impossible to track candidates who don't get an offer.)