Author: Christophe Theron
Date: 09:30:19 12/18/99
Go up one level in this thread
On December 17, 1999 at 20:23:21, Vincent Lejeune wrote:
>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 ! ;)
Thanks Vincent. I keep it in my archives.
Christophe
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