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Subject: Re: in search of a formula for calculating confidence intervals

Author: Renze Steenhuisen

Date: 02:18:18 01/17/06

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It is my opinion that you have winning and not-winning. Doesn't matter if
not-winning consists of draws and losses.

On January 17, 2006 at 05:07:22, Joseph Ciarrochi wrote:

>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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