how to convert match score to ELO difference
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how to convert match score to ELO difference
Can somebody point me to a reference showing how to convert match scores into ELO differences? E.g. if A and B play a thousand games, and A's winlossdraw is 250200550, what ELO difference between A and B does that indicate?
Re: how to convert match score to ELO difference
Here's a table : http://www.pradu.us/old/Nov27_2008/Buzz/elotable.htmljack512 wrote:Can somebody point me to a reference showing how to convert match scores into ELO differences? E.g. if A and B play a thousand games, and A's winlossdraw is 250200550, what ELO difference between A and B does that indicate?
And a formula : https://en.wikipedia.org/wiki/Elo_ratin ... nce_rating
(250200)/1000*400 = +20 > Performance of A is 20 Elo over B.
Last edited by Vinvin on Fri Mar 10, 2017 4:56 am, edited 1 time in total.

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Re: how to convert match score to ELO difference
http://www.3dkingdoms.com/chess/elo.htm
If you right click on the page and show page source, you can see the underlying code that calculates it.
It gives +17 Elo difference for your 250:200:550 sample
If you right click on the page and show page source, you can see the underlying code that calculates it.
It gives +17 Elo difference for your 250:200:550 sample
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 Ajedrecista
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Re: How to convert match score to Elo difference?
Hello John:
You can also use the ratio points/games:
Just to have a general idea, you can see an image of logit function here:
Then imagine that the horizontal axis is µ and the Elo difference is more less the vertical axis of that image multiplied by 173.7.

In your example:
Regards from Spain.
Ajedrecista.
I would use the standard formula, already pointed by Dann. I will explain it a little more:jack512 wrote:Can somebody point me to a reference showing how to convert match scores into ELO differences? E.g. if A and B play a thousand games, and A's winlossdraw is 250200550, what ELO difference between A and B does that indicate?
Code: Select all
games = wins + draws + loses
points = wins + draws/2
(Elo difference) = 400*log10[points/(games  points)]
It is valid when 0 < points < games
Code: Select all
µ = points/games
(Elo difference) = 400*log10[µ/(1  µ)]
0 < µ < 1 as above
(Elo difference) = [400/ln(10)]*ln[µ/(1  µ)] = [400/ln(10)]*logit(µ)
(Elo difference) ~ 173.7178*logit(µ)
Then imagine that the horizontal axis is µ and the Elo difference is more less the vertical axis of that image multiplied by 173.7.

In your example:
Code: Select all
games = 250 + 550 + 200 = 1000
points = 250 + 550/2 = 250 + 275 = 525
(Elo difference) = 400*log10[525/(1000  525)] = 400*log10(525/475) ~ 17.39 Elo
Ajedrecista.