Advanced chess ratings calculation

  

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Thibault de Vassal    (2010-04-05)
Advanced chess ratings calculation

For some reasons that I'll explain below, I updated the advanced chess (bullet, lightning, blitz, freestyle) rating calculation rules to the following :

"Performance = Opponent Current Rating if the game is drawn, + 350 if the game is won, -350 if the game is lost.

The following bonus / malus applied to White and to Black makes ratings fair, as it is not possible to force a player to take White or Black before a game :

(White) Performance = Performance - 50
(Black) Performance = Performance + 50

If there's a winner and if his rating is below 2400, his new rating his :

New Rating = ((8 x Current Rating) + (2 x Performance)) / 10

Otherwise :

New Rating = ((9 x Current Rating) + (1 x Performance)) / 10

The rating calculation does not take account of wins obtained by a stronger player when the Elo difference is greater than 350 points, the same with losses by a weaker player.

In case of a draw or loss against a player rated more than 200 points less, the opponent's rating considered in calculation is : Current Rating - 200. A player who wins a game cannot lose Elo points, a player who loses a game cannot win Elo points."

More details :

http://www.ficgs.com/membership.html#rating_advanced_chess


The rule that just changed is "If there's a winner and if his rating is below 2400, his new rating his : New Rating = ((8 x Current Rating) + (2 x Performance)) / 10".

This rule will probably be updated again in a few months with a rating limit of 2200 instead of 2400, when advanced chess ratings will be more coherent with correspondence chess ratings.

The reasons are :

1) Advanced/freestyle chess is often neglected partly because players will likely lose some rating points (many strong players using Rybka 3-like engines still have a rating of 1800 or 2000, there are several reasons to this), the main point is probably the interface but I'm fixing it (e.g. the new touch-move option - see Preferences).

2) Chess engines are just stronger and stronger while the ratings do not increase with the previous rules, as a consequence players who just tried advanced chess once years ago shouldn't still top the rating list. It is of course a way for players to find their place quicker in the rating list & to incitate players to play more games as well.


Thibault de Vassal    (2010-04-19 16:41:06)
Advanced chess ratings calculation

As advanced chess (not correspondence chess) ratings move too fast, I just updated the calculation rules :

If there's a winner and if his rating is below 2400, his new rating his :

New Rating = ((18 x Current Rating) + (2 x Performance)) / 20

Otherwise :

New Rating = ((19 x Current Rating) + (1 x Performance)) / 20