1.9. Does Go have an equivalent to ELO rating?
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This article is from the Go FAQ, by Morten PAHLE gofaq@pahle.org.uk with numerous contributions by others.
1.9. Does Go have an equivalent to ELO rating?
Beginners often compare Chess and Go and ask whether the rating
systems in both games are related.
The Elo system in Chess attributes a rating figure somewhere between
800 (beginners) and 2700 (top grandmasters) to every player. This
rating changes depending on the performance of the player in
tournaments. The basic idea of Elo is that a player should have a
winning expectancy of 69% (or, more precisely, an expected score of
69) against another player whose Elo rating is 100 points less.
In the recent history of Go, there have been various attempts of
translating this system to our game. The most popular model is the
European Rating List, maintained by Ales CIEPLY at
<http://www.european-go.org/rating/gor.html>
The basic observation in Go is that the winning expectancy against a
player one grade weaker roughly equals 69%, as well. Therefore, it
seems natural to translate Go grades to Elo ratings by using steps of
100 for every grade. Ales does so by defining 1 dan = 2100 points.
Consequently, 1 kyu = 2000 points, 2 dan = 2200 points, etc. A player
with 2050 points is called a weak shodan, whereas a player with 2150
goes through as a strong shodan.
However, there are two major problems with this system.
Firstly, the winning expectancy of 69% per grade is no constant in Go.
It seems to be lower in the weak kyu range and higher in the strong
dan range. (The reason for this seeming paradox is that strong dans
play more consistently and less erratically than weak kyus.)
Therefore, Elo's formulae have to be adjusted in complicated ways to
fit the game of Go with the scale mentioned above.
Secondly, the traditional grade system 'kyu - dan' is much more
popular among Go players than any attempt of an Elo system. Most
amateur Go players simply ignore their Elo ratings and rate themselves
according to the grade system.
This low acceptance of Elo ratings in Go gives them only small
significance at the moment. This might change sometime in the future,
but probably not all too soon.
There is a rating system similar to Elo among Chinese professionals.
But as with European amateurs, it does not seem to work very well.
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