Author: Renze Steenhuisen
Date: 01:01:57 01/17/06
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On January 17, 2006 at 03:52:21, Joseph Ciarrochi wrote: >Does anybody have the formula for calculating standard error bars for win >percentages? e.g., given a a sample of N, and an observed win rate of x %, I 'd >like to construct a 95% confidence interval around x. > >It would also be cool if you had the formula for calculating confidence >intervals for ratings? > >best >Joseph If you have M positive occurences of a certain event (i.e., a win), from N samples. Then, the %-interval is given by: (M + (L^2)/2 \pm L*SQRT(M*(1-(M/N))+(L^2)/4)) / (N + (L^2)) with \pm being minus for the lowerbound, and plus for the upperbound. L depends on the %-confidence you like. 95% confidence needs L=1.96. Cheers Renze Steenhuisen
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