Bayes' Theorem explained by Yudkowsky

http://yudkowsky.net/rational/bayes

by spydez • 18 years ago

57 25 18 years ago

yudkowsky.net

Retric3• 18 years ago

It's always surprising that most people are that bad at math.

.01 x .8 /(.01 x .8 + (.99 x 9.6 / 100)) ~= 0.0776 or 7.8%

tl• 18 years ago

Sure, but we expect doctors (who receive much greater education and compensation than most people) to get it right.

dhbradshaw• 18 years ago

What's alarming and interesting isn't that they have a lot of years of school and miss this, but that interpreting diagnostic tests correctly is a core part of their job and they miss it. How many lives are adversely effected and how many billions are wasted by doctors making inappropriate decisions because they don't know how to interpret data correctly?

bd• 18 years ago

Around 15% got it right, which is quite consistent with Sturgeon's Law:

http://en.wikipedia.org/wiki/Sturgeon_law

soldarnal• 18 years ago

And in particular with probability. It's amazing how difficult it is for people to fake random data.

If you ask half a class to actually perform and record 100 coin flips and half to fake the data, it's almost trivial to guess which is which either by looking for a string of 5-6 heads or tails in a row (which humans almost never have), or by calculating the percentage flips following a heads that are tails (which should be ~50%, but for humans tends to be much higher).

kirse• 18 years ago

Do significant digits matter in these sort of probability calculations?

Secondly, do we want doctors to tell us the probablility estimate that we have cancer or do we want doctors to tell us Yes or No?

Personally, I don't care what my probability score is if the answer is "No". Even if the answer was "Yes", an optimistic person would ignore the odds anyway.

gjm11• 18 years ago

Yes, I want the probability estimate, because I want the best information available in that sort of situation. And the word for someone who ignores the odds is not "optimistic" but "foolish", unless the answer makes no difference to your behaviour. (Which is pretty unlikely in the case of cancer.)

aswanson2• 18 years ago

Went back and re-read his tribute to his brother/exhortation to move forward science again. It's like You and Your Research on steroids. If that essay doesn't motivate you, I don't know what will. Insanely brave.

anewaccountname• 18 years ago

link?

rms4• 18 years ago

http://yudkowsky.net/other/yehuda

yters3• 18 years ago

Has someone figured out a way around the 2nd law of thermodynamics? Or is it not a law anymore? I'm not a physicist, so I don't know these things.

rms4• 18 years ago

http://www.multivax.com/last_question.html

herdrick3• 18 years ago

[java applet] [java applet] [java applet] [java applet] [java applet]

herdrick3• 18 years ago

Which is not to say you shouldn't click! In fact these are the most useful Java applets I've ever seen. He still should've done them with Flash, though.

rms4• 18 years ago

This is my favorite writing by Yudkowsky: http://www.overcomingbias.com/2008/05/faster-than-ein.html

jcl• 18 years ago

It bugs me a little that he starts using the phrase "prior probability" before defining it. If your vocabulary already included the word "priors", you probably wouldn't need a Bayes tutorial. :)

Bayes' Theorem explained by Yudkowsky

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