Author: James T. Walker
Date: 18:59:36 10/30/04
Go up one level in this thread
On October 29, 2004 at 13:24:00, Sune Fischer wrote: >On October 29, 2004 at 12:27:15, Uri Blass wrote: > >>Let assume that every player play 12 games against 1400 players >>I want to give an estimate for the level of the player based on the result after >>4 games. >> >>part of the players who score 0 out of 4 will score more than 0 out of 12 >> >>A good estimate remain the same in average when you play more games(it becomes >>higher for players who do more than expected but also becomes smaller for >>players who do less than expected). >> >>If your estimate based on 0/4 is the same as your estimate in case of 0/12 it >>means that players who score 0/4 can only improve their rating after they play >>more games and it is not logical. >> >>The average level of players who score 0/12 is lower than the average level of >>players who scored 0/4 because players who scored 0/4 consist also players who >>can expect to score results like 1/12. >> >>Uri > >A players rating is connected to his expected score. > >I'd say if he scores 0/4 the best guess we can make on his expected score >is 0.25/4, so right between getting nothing and getting a single draw. > >This is of course because the actual score is descrete while the probability >is continuous, he cannot score his expected in that short a match. > >So assuming he scored 0.25 of 4 against a 1400 player his estimated rating >(big error margins of course) would be 930. > >If he got 0 of 12, his expected score 0.25/12 would give a rating of 731 ELO. > >Likewise, had he won 4/4 (ie. 3.75/4) he would be rated 1870 and 12/12 would >give 2069 ELO. >If he wins 100/100 the rating would be 2440, 1000/1000 it would be 2840. > >So I guess a 1400 player would be expected to draw Kasparov once in abourt 1000 >games. > >-S. As long as you realize you are making a "best guess" and not giving a real rating that's fine. The problem is that in real life untill you actually score some real points you cannot get a score which is anything but a guess. The formula assumes you are 400 points below the average opponents and that is true in both cases cited above. Nobody says it's perfect. It's only an attempt to give a provisional score untill some concrete data is available. The 400 points below your opponents average is as good a guess as any and easy to calculate. Also how did you come up with a win expectancy of 1/4 point? Simply because that's the next possible score closest to zero? Jim
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