Thursday, 14 February 2013

Yet another handicap scoring sysetem

This is based on something I saw in a tournament report from the Noble Park Chess Club in Melbourne, although it may have also been tried elsewhere. Instead of scoring each game as 1, 1/2, 0 you score the game based on rating differences between the two players. The higher rated player always receives 1 point for a win (and 1/2) for a draw, and the losing player receives 0 for a loss, but in the case of an 'upset win or draw, the lower rated player may receive more points.
For example, a player wins against an opponent rated 125 points above them. As the expected score is 33% (or 2-1 in favour of the stronger opponent) the lower rated player would score 2 points for a win. In the case of a draw it would be 1 for the lower rated player, with the higher rated opponent still receiving 0.5.
Of course this is a system that essentially rewards upset results, although it does not prevent  the top seeds from doing well. Probably suitable for a fun blitz event, or even as extra handicap prizes in other events, but clearly not as a replacement for more traditional scoring systems.

Here is the scoring table (based on possibly inaccurate back of the envelop calculations).
To keep the numbers sensible only multiples of 1 and 0.5 are used (ie no quarter points)

Rating diff    W   D
>0               1     0.5
>72             1.5  0.5
>125           2.0  1.0
>158           2.5  1.0
>193           3.0  1.5
>211           3.5  1.5
>240           4.0  2.0
>262           4.5  2.0
>273           5.0  2.5

To calculate these numbers simply divide N/(N+1) and look up the percentage on the standard ELO Dp table. Interestingly the gaps between the each score group get smaller as N increases.

1 comment:

Chris Skulte said...

Has there ever been a tournament where you get your opponents rating in points?
i.e. A(1200) plays (B)800.
A wins = A-800 B-0
Draw = A-400 B-600
B wins = A-0 B-1200

Though I am unsure how the matchmaking system would work. Also this would probably only work over longer round tournaments.