Author: Vincent Lejeune
Date: 17:23:21 12/17/99
Go up one level in this thread
On December 17, 1999 at 14:58:20, Christophe Theron wrote: >On December 16, 1999 at 20:08:25, Dann Corbit wrote: > >>On December 16, 1999 at 19:09:09, pete wrote: >>>On December 16, 1999 at 18:50:55, robert michelena wrote: >>[snip] >>>>Seriously, my highest rating was around 1620. >>[snip] >>>then if you are really serious which I tend to believe to some extent look at >>>the ELO system ; now assume for one second the progs play at about 2500 USCF . >>>Ok ? >>> >>>Ok , you have your own experiences ( them progs are simply unbeatable , which is >>>predictable as the rating difference should be about 900 points to you ) , but >>>now think about a player rated about 2000-2100 USCF which is _far_ away from >>>master strength ; see the number of points he can expect from the top programs ? >>> >>>Do you think you really are competent to make a fair judgement here ? >> >>Using the above as a 'frinstance to model with, >>The oft repeated table: >> >>Win expectency for a difference of 0 points is 0.5 >>Win expectency for a difference of 100 points is 0.359935 >>Win expectency for a difference of 200 points is 0.240253 >>Win expectency for a difference of 300 points is 0.15098 >>Win expectency for a difference of 400 points is 0.0909091 >> >>2500 - 2050 = 450. >>Between 9 % 5% of points will be won by that difference. >>An occasional win should not be at all surprising. With 100 gmaes played, if >>your rating were 2100, you should get 9 points (on average). Anything from 18 >>draws to 9 wins. >> >>Win expectency for a difference of 500 points is 0.0532402 >>Win expectency for a difference of 600 points is 0.0306534 >>Win expectency for a difference of 700 points is 0.0174721 >>Win expectency for a difference of 800 points is 0.00990099 >>2500 - 1620 = 880. >>Between 1% and 1/2 of 1% of the points will be one (much closer to 1/2 of 1%) >>So play 100 games under tournament conditions to get one draw. >> >>Win expectency for a difference of 900 points is 0.00559197 >>Win expectency for a difference of 1000 points is 0.00315231 >> >>I don't think (however) that an argument from math will prove effective either. >> >>I'll bet that the really good players like Vincent score remarkably well against >>programs (unless their Achille's heel is tactics). > > >That's interesting, Dann. > >Do you have a formula that gives the win expectancy from the elo difference, and >the opposite formula too? > >I would like to have both, but I'm not good enough in maths. > > > Christophe There is a Simple formula BUT it does ONLY for elo difference below 200 elo points and for win/lose within 20% to 80% ; As the function is pretty linear in this interval: (Win (in %)-50)*7 give the elo difference (difference between elos/7)+50 give the theorical percentage of win EXAMPLE: 1) player A have 50 more elo points than player B : (50/7)+50= 57% win expectancy for A 50-(50/7)= 43% win expectancy for B 2) A make 60% against B : (60-50)*7= +70 Elo perf for A (50-60)*7= -70 Elo perf for B The purists would say that this formula is not general, but it's so simple that it's very usefull ! ;)
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