Author: Osorio Meirelles
Date: 13:48:10 04/26/02
Go up one level in this thread
On April 26, 2002 at 09:29:26, Gian-Carlo Pascutto wrote:
>Given a score from a series of games, y, we can calculate
>the ELO difference between the two players as:
>
>x = -400*log((1-y)/y)
>
>My question is now, how do we calculate the error margins
>on this value?
>
>--
Gian-Carlo, I would recomend that first we get the standard deviation for y,
which is :
std(Y) = square_root( y*(1-y)/ n ) where n is the number of games.
A 95% confidence interval for y is:
[ y - 1.96*std(Y) , y + 1.96*std(Y)]
make h1 = y - 1.96*std(Y) this is the y lower bound
make h2 = y + 1.96*std*(Y) this is the y upper bound
Since x = -400*log((1-y)/y), the confidence interval for x would be:
-400*log( (1-h1)/h1) ) lower bound
-400*log( (1-h2)/h2) ) upper bound
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