Author: Dieter Buerssner

Date: 10:26:17 01/09/04

Go up one level in this thread

On January 09, 2004 at 08:53:58, Peter Fendrich wrote: >On January 07, 2004 at 12:23:00, Dieter Buerssner wrote: >> [...]But now assume Player A won all his games with white, and >>additionally 20 games with black. No draws. Again m=0.51. W/D/L the same as >>above. > >Just to check if I got it right: You mean that A plays 490 white games and 510 >black games? No. Sorry, a typo above. I meant Player A won additionally *10* games with black. The other numbers I cited were correct (I really did the simulatatian and fit with wW=500, bW=10, bL=490, no draws, other numbers are fixed with these conditions already). Thanks for your (other) comments (that I snipped). >I think I've sent you the text describing it otherwise give me a hint. Yes, I have it. >>No problem with me, to disuss it in email. I just thought, I post an followup >>here, and try to explain it a bit clearer. Perhaps, we are not the only 2 >>persons interested. > >Maybe so, I doubt there are more ... You are more realistic than me :-) Ricardo and Andrew Dados (?) in the past also were interested in such discussions. Also Christophe, and of course Remi (whose paper and program I know). >>I guess, you are referring to the Elo calculations. > >Yes > >>I think, the Elo just complicates things, without giving more insight. > >:-) >I wouldn't put it that way. It's the other way around. The -400LG(x) formula is >a simplification. But is it exact? Perhaps I formulated bad, again. Actually, I don't think that the calculation of the margins in "Elo-domain" is bad. But we will be able to do it easily - the error margin in the score is more basic. About the Elo formula ("400LG"). Actually I thought until very recent, that the Elo formulas use a normal distribution (and Elo's original approach did). Recently I learned (from Glickman's (sp?) papers) that USCF and FIDE use the logistic distribution instead (the LG formula). I am still puzzled. There is only very little differnece between the two -it can be seen in the tails, however (when rating difference is huge - say over 400). I tried to calculate the tables given at FIDE and at DSB (Deutscher Schach Bund). They neither totally agree with my calculations (in the last given digit), whether I take the logistic distribution or the normal distribution (I used a reliable erf() for the later, that has very high accuracy). The numbers from the normal distribution, seem to fit slightly better to the numbers given in the tables. I used for the normal distribution: p = 0.5 - 0.5*erf(rating_difference/400.) and p = 1-1/(1+10^(-rating_difference/400)) for the logistic distribution. The FIDE table is at http://www.fide.com/official/handbook.asp?level=B0210 It does not mention, how the numbers were calculated (or I have overseen it). Regards, Dieter

- Re: A question about statistics...
**Peter Fendrich***05:05:34 01/12/04*

This page took 0.03 seconds to execute

Last modified: Thu, 07 Jul 11 08:48:38 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.