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Subject: Re: How do I compute an unrated program's rating after a series matches?

Author: Odd Gunnar Malin

Date: 04:01:57 03/18/05

Go up one level in this thread


On March 18, 2005 at 05:04:18, Tony Hedlund wrote:

>On March 18, 2005 at 00:35:00, emerson tan wrote:
>
>>On March 18, 2005 at 00:27:04, emerson tan wrote:
>>
>>>I want to know the rating of Frizt 5.32 on Athlon 1200Mhz, so I run a series of
>>>matches with programs that have established ratings.
>>>
>>>Supposed Fritz 5.32 scored from the following matches:
>>>
>>>Junior 8.0       elo 2782   14.5 - 5.5     Fritz 5.32
>>>Shredder 7.0     elo 2772   12.0 - 8.0     Fritz 5.32
>>>Deep Frizt 8.0   elo 2790   16.0 - 4.0     Fritz 5.32
>>>Chess Tiger 14.0 elo 2719   11.5 - 8.5     Frizt 5.32
>>>Hiarcs 9.0       elo 2747   13.5 - 6.5     Frizt 5.32
>>>
>>>How do I compute the elo of Fritz 5.32 ?
>>>
>>>Thanks
>>
>>
>>I can only see some plus or minus from its matches but no elo rating.
>
>average elo+  400*(won-lost)/games
>
>2762+ 400*(32.5-67.5)/100
>
>2762-140 = 2622
>
>Tony

Hi.

Your formula are correct for unrated players but do you have the correct formula
to calculate performans for rated players.

First I used this approx:

score=points/games
average=average of opponents rating.

perf=(average-400*log10((1.0-score)/score)

This gives maybe correct performance rating around 50% score but as soon as you
go a bit away the error get bigger.

Then I tried from Excel with this:
perf=average+NORMSINV(score)*ROT(2)*200
This gives a much better result and the error is only when the score get close
to 100% (or 0%)

It kind of hard for me to remember all these math, it have been 26 years since I
left the school so I'm luck if I even remember correct the names like standard
deviation, standard distribution etc. so if you or other have a table with this
calculated out with 3 decimals (0.001, 0.002 ...) for the score it would have
been nice.
I will create this table myself with the help of the table for 2 decimals (from
Fide or elsewhere) and use the excel formula to find the in between numbers.

What the usage?
I have written a program to post results/tables to the internet (add result plus
one click and it on the net) that we have been using in tournaments for live
coverage the last 3-4 years.
I use the formula with log10 now, but someone may check the program with
tournamentresults found at Twic etc. and see that the performance isn't
calculated correct. So instead of calculate the result I will change it to look
up the numbers from a table

Odd Gunnar



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