jimrandomh comments on Conditioning on Observers - Less Wrong

6 Post author: Jonathan_Lee 11 May 2010 05:15AM

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Comment author: jimrandomh 11 May 2010 05:09:33PM *  0 points [-]

P(H)=P(H|W)P(W), where P(H)=1/2 and P(H|W)=1/3

No, P(H)=P(H|W)P(W) is incorrect because the W in P(H|W) is different than the W in P(W): the former is a probability distribution over a set of three events, while the latter is a boolean. Using the former definition, as a probability distribution, P(W) isn't meaningful at all, it's just a type error.