Author: Joseph Ciarrochi
Date: 02:07:22 01/17/06
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thank you. that's great!. I assume that this formula does not require dichotomous data,e g., it is approrate for data with losses wins, and draws? best Joseph On January 17, 2006 at 04:01:57, Renze Steenhuisen wrote: >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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