Jack_S

Quick Summary * Collider bias and Berkson's paradox are pretty common and often neglected * I think it's not just a niche statistical concept: it explains a bunch of interesting stuff, and has some use in applied rationality * Scott Alexander has written about something similar, and there's a LW post that explains some of the findings in an accurate but slightly dry way. This post tries to make it clear and more readable Preamble It’s your first day in prison. Despite your insistence that the man who approached you and asked for your wallet in exchange for preventing an infinitely large amount of future suffering had in fact been mugging you, your claim of self-defence fell through. The judge tells you that, judging by the severity of your crime and your assessed mental stability, you will be sent to a medium-security prison for three years. Each prisoner has one cell-mate. You know that whether this guy is nice or nasty might determine whether your whole time in prison is moderately unpleasant or a living hell. You walk in and see him leaning against the bed. He looks relatively normal for a prisoner—muscular, no visible gang tattoos, serious expression. You ask with apprehension: “So…what are you in for?” “Serial murder.” Relief floods over you and you instantly hug the surprised murderer, who smiles a little apprehensively, and gives you an awkward pat on the back: “What was that for?” Back to school Do you ever find yourself wondering why the smartest people around you seem to be less hard-working? Or why the more hard-working people don’t seem to be super smart? If not, I can guess why! We’ll come to you later. But if so, fantastic, let’s start by verifying your intuitions. Imagine the situation, you’re 11 years old in a British comprehensive school in a fairly mixed-income area of the UK. After the Christmas holidays, your school year is divided into 6 ability-based sets for each academic subject, determined by your classwork and exam results