Class 10: Minding Your Ps & Qs & Monty Hall

Lesson 10: Every time, without fail, when you hear somebody say "The probability of P is x", ASK FOR THEIR Q. Reminder: all probability fits the schema Pr(P|Q). Therefore we must always know what the Q is. And we must know before P has been revealed to us. Anybody can come up with a post hoc Q that gives a high value for P. Anybody. Indeed, all mainstream statistics relies on this trick. Never fall for it. Insist on demonstrating real predictive accuracy. Get their Q before P is revealed. We also do the infamous Monty Hall Problem, which shows how difficult finding Q is.

All questions will be answered in the following Monday's lecture.

Written lecture: https://www.wmbriggs.com/post/51979/
https://wmbriggs.substack.com/

Permanent class page: https://www.wmbriggs.com/class/