Author: Stephen A. Boak
Date: 22:10:25 10/23/04
Go up one level in this thread
On October 23, 2004 at 18:47:26, Vincent Lejeune wrote: >On October 23, 2004 at 16:37:37, Stephen A. Boak wrote: > >>On October 22, 2004 at 18:52:13, Uri Blass wrote: >> >>>On October 22, 2004 at 18:30:34, James T. Walker wrote: >>> >>>>On October 22, 2004 at 13:32:57, Uri Blass wrote: >>>> >>>>>go to the following link >>>>> >>>>>http://georgejohn.bcentralhost.com/TCA/perfrate.html >>>>> >>>>>enter 1400 for 12 opponents >>>>>enter 0 for your total score >>>>> >>>>>Your performance is 1000 but if you enter 1 to your total score your performance >>>>>is only 983. >>>>> >>>>>It seems that the program in that link assume that when the result is 100% or 0% >>>>>your performance is 400 elo less that your weakest opponent but when your score >>>>>is not 100% it has not that limit so they get illogical results. >>>>> >>>>>Uri >>>> >>>>My take on this is they are using a bad formula or have screwed up the program >>>>to calculate the Rp. >>>>The USCF uses Rp=Rc + 400(W-L)/N >>> >>>It seems that the USCF does not do it in that way >>> >>>They admit that the formula is not correct for players who won all their games >>> >>>Note: In the case of a perfect or zero score the performance rating is >>>estimated as either 400 points higher or lower, respectively, than the rating of >>>highest or lowest rated opponent. >>> >>>It is probably better to estimate the preformance based on comparison to the >>>case that the player did almost perfect score. >>> >>>Uri >> >>Dear Uri, >>What is the *correct* formula for a player who has won (or lost) all his games? >>:) >>Regards, >>--Steve > > >For such a player, the error margin = infinity > >the perf = average opp +400 to +infinity
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