Author: Komputer Korner
Date: 05:53:35 07/30/98
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On July 30, 1998 at 00:48:21, Shaun Graham wrote: > How are computer chess program ratings calculated, what is the formula? >It has occurred to me that perhaps it makes no sense to calculate computer >ratings in the way that human ratings are calculated. It's hard to describe my >point so i will give an example. > >A human rated 2200(base rating) plays a tournament of ten games, after the >tournament his rating is calculated to be 2280. Arriving at this calculation >his initial rating of 2200 was used. In his next tournament of ten games his >rating is calculated to be 2320. To arrive at this rating 2280 was used in the >base calculation. This seems to work for humans because you can hypothesize >improvement thus a new base rating works, but for computers it seems as if >having a new base rating may be problematic because their is no so called >"improvement". In a way it seems to me that it all works fine and I know the >rating is supposed to just measure performance but i just have an intuitive feel >that there should be a difference in the calculations. > >Another problem that i have is that say i have 50 tourney games played, and i >calculate the rating in ten game increments. I use the new rating achieved >after each ten as the base to do my calculation. my final rating is different >than if i acted as if all the games happened in one tournament. Perhaps i'm >screwing the calculation? > > >I have hypothesized that to calculate the rating of a program based upon all the >games played at once you should use the provisional formula > >For example Chessmaster 5555 on Kai Luebke's web page >"http://www.geocities.com/TimesSquare/Ring/8448/chessindex2.html" in 40/2 games >has won 29 games, drawn 13, lost 11 games. I gave a flat rating of 2400 to all >opponents > >the calculation went as follows [(29wins * 2400)+(29wins*400)] + [(13draws * 0)+ >(13draws * 2400)] + [(11Loss * 2400)-(11Loss * 400)] = 2535(Chessmaster is a >MONSTER) > >This is the standard uscf formula of adding 400 points to opponents ratings for >wins, and subtracting 400 for losses, then dividing by the number of games >played for a provisional rating. > >The opponents were Rebel9 & 8, Mchess 7, Fritz 5, Hiarcs 4 & 6, crafty 14.8, >Junior 4.6, and Genius 5. While your way of (not calculating an interim rating and waiting until all the games were put in at once and then doing an all at once calculation is more accurate) it is not practical because only one program's rating could be calculated this way. All the other ones would have to have interim ratings in order for your method to work. So you see the present system is the only one possible. There are different ways of doing incremental calculations. The system in practice is to take lump sum tournament date starting and endpoints and the other way would be to do it after each round. The increased mathematical accuracy does not justify the increased cost however. -- Komputer Korner
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