An Open Thread: a place for things foolishly April, and other assorted discussions.
This thread is for the discussion of Less Wrong topics that have not appeared in recent posts. If a discussion gets unwieldy, celebrate by turning it into a top-level post.
Update: Tom McCabe has created a sub-Reddit to use for assorted discussions instead of relying on open threads. Go there for the sub-Reddit and discussion about it, and go here to vote on the idea.
P(Observing doomsday) = P(Being in some class of people) * P(Observing doomsday | you belong to the class of people)
You get a different probability for belonging to those classes, but the conditional probabilities of observing doomsday given that you belong to those classes are different. I'm not convinced that these differences don't balance out when you multiply the two probabilities together. Can you show me a calculation where you actually get two different values for your likelihood of seeing doomsday?
Maybe I'm misreading this, but it looks like you're missing a term...
You said: P(O) = P(B) * P(O|B)
Bayes's theorem: P(O) P(B|O) = P(B) P(O|B)
ne?