Tordmor comments on Hearsay, Double Hearsay, and Bayesian Updates - Less Wrong

47 Post author: Mass_Driver 16 February 2012 10:31PM

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Comment author: [deleted] 16 February 2012 08:09:53AM 1 point [-]

I don't see how those are "the same question". If out of 8 accused 4 are guilty and two of them are convicted, the rest acquitted. Than p(guilty|convicted) = 1 and p(innocent|acquitted) = 2/3.

Comment author: skepsci 16 February 2012 08:25:26AM 4 points [-]

The assumption was that 80% of defendants are guilty, which is more than 4 of 8. Under this assumption, asking whether p(guilty|convicted) > 80% is just asking whether conviction positively correlates with guilt. Asking if p(innocent|acquitted) > 20% is just asking if acquittal positively correlates with innocence. These are really the same question, because P correlates with Q iff ¬P correlates with ¬Q.

Comment author: [deleted] 16 February 2012 08:27:31AM 0 points [-]

Perfect. Thanks.