From: Sam Sloan ISHIPRESS COM> Date: 26 oct 2002 Subject: Re: Elo system At 04:31 PM 10/26/2002 +0200, Albrecht Heeffer wrote: >Hello all, > >Chessbase.com features an article by statistician Jef Sonas with >a proposal to improve the ELO rating system. He advocates a simpler linear >formula to calculate the expectancies and argues that this provides >a better predication than the current ELO system. I find his article >quite convincing. The shogi world could be first to adopt the Sonas >system. >http://www.chessbase.com/newsdetail.asp?newsid=562 > >Greetings, > >Albrecht Heeffer This is a very interesting article and well worth reading. However, it does not apply to shogi at all. The author correctly notes that there are differences between Elo's formula and reality. For example, according to the Elo Formula, if two players are 200 points apart, the higher rated player will score 75%. However, it has been discovered that in reality the higher rated player will only score 73%. This has been know for a decade and the USCF rating system was long ago adjusted accordingly. I also agree that the K-Factor does not matter much. Regardless of whether K is set at 5 or 50, the ratings will still come out about the same in the long run. The reason this does not apply to shogi is that differences in strength are sharper. When I was playing as a 2-dan player regularly, whenever I was paired against a 1-dan player I won 100% of the time. I think that this experience is fairly typical. That would translate to about 400 points in the Elo System. Amateur Shogi Players range from a bottom of about 7-kyu to a top of about 7-dan, although some players are highter than that top or lower than that bottom. That is 14 ranks and only counts amateurs, not professionals. In chess, the lowest rating among adults (not counting scholastic players) is about 1000 and the highest rated player in the world is Garry Kasparov, who is rated about 2800. In chess, one grade is 200 points. Class B is 1800, Class A is 1800 and Expert is 2000. So there are nine grades in chess from the weakest player in the world at 1000 to the strongest player in the world at 2800. Finally, in chess it is possible to do a statictical study of 100,000 games. One World Open Chess Championship in Philadelphia, held every July 4, will produce results for more than 5000 rated games. In shogi, very few results are recorded. Larry Kaufman is working on shogi ratings but I doubt that he has the results of more than a few hundred games in his database. Sam Sloan