Author: Andrew Wagner
Date: 13:39:38 05/25/04
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On May 25, 2004 at 15:49:22, Bas Hamstra wrote: >Supposed you played a huge automated tournament, and ratings were automatically >calculated (like in Arena) and displayed for all participants. Then, would it be >possible to derive/calculate the sigma, 2*sigma, 3*sigma rating >rating-intervals? If so how? > > > >Ciao, > >Bas. Hi. I'm not sure what you mean by 2*sigma and 3*sigma. The are not statistically significant, so far as I know. Variance is sigma^2 (i.e. sigma * sigma). The formula for this is: sum((x - average)^2)/N. So, let's take a few ratings for an example: 2400 2432 2414 2443 The average is 2422.25. Therefore, we have (22.25^2) + (9.75^2) + (8.25^2) + (19.75^2) in the numerator. That's 1048.25. And our N here is 4 because we have 4 ratings, so our answer is 1048.25/4 or 262. That's the variance. Taking the square root, we get 16.2, which is sigma (standard deviation). Hope that helps. Andrew
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