>>16904275
If you have no evidence everything you believe is correct

>>16904275
You know how there's some probability that a random member of the population doesn't understand Bayes? So suppose you have a random member of the population. But then you find out that person browses /sci/. Suddenly, in light of that knowledge, the probability that person doesn't understand Bayes jumps to ~1. That's Bayes.

evidence updates probability. 3 words, new understanding

idk anything about bayes although I've heard the name a lot. I took a test a while ago that was a pilot for a standardized test of some kind. quite a few of the questions were something like
>there are 80 chemistry majors and 20 english majors
>one person is chosen at random
>the person who was chosen likes poetry and keeps a journal
>is the chosen person more likely to be a chemistry major or english major?
I answered all of these questions using the probability given by the relative size of each group without reference to these other traits. based on this thread it would appear that I got all of those questions wrong, which is somewhat hard to believe considering I did very well overall but I guess it's possible as it was a full length test with many different sections. I just thought it was some kind of trick question.

>>16904364
In your example, you only have P(A), so that's what you're gonna go by.

>>16904277
My prior is that you're a butt head.

>>16904394
>he doesn't have the prior of poetry and english majoring being correlated

>>16904449
Ok. So what's your choice of P(B|A) and P(B) based on "poetry and english majoring being correlated"?

All you need to know about Bayes is he's the GOAT

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>>16904730
>P(english major|poetry) = P(poetry|english major) * P(english major) / P(poetry)
> P(poetry|english major) = 1
All English majors write poetry.
>P(english major) = 0.2
20 out of 100 duh
>P(poetry) = 28 / 100
Only one in ten stem nerds write poetry. This is GENEROUS.
70% chance the journal came from an english major, absolute minimum.

>nooo you can't just do it like that you're making up numbers
And yet I got the right answer, and you got the wrong answer. Funny how that works.

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>>16905187
>And yet I got the right answer, and you got the wrong answer. Funny how that works.

>>16904275
https://www.lesswrong.com/w/bayes-rule?lens=bayes-rule-guide
https://betterexplained.com/articles/an-intuitive-and-short-explanation-of-bayes-theorem/

>>16904275
>bayes
he's a wise guy