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Game Courier Ratings. Calculates ratings for players from Game Courier logs. Experimental.[All Comments] [Add Comment or Rating]

Gary Gifford wrote on Tue, Jan 10, 2006 07:30 PM EST:

The CxR concept is as follows... and to use it for CV seems easy.

New Rating = Your Old Rating PLUS (Score x 21) PLUS (Pre-Game Rating of
Opponent MINUS Your Pre-Game Rating) [divided by 25]

where Score is +1 for a WIN, 0 for a DRAW,  -1 for a LOSS

So, if I am 1800 and my opponent is 1900 and I win:

My New Rating would be:  1800 + (1 x 21) + (1900 - 1800)/25
My New Rating would be:  1800 + 21 + 4 =   1825

For the 1900 guy I played we'd see:
His New Rating = 1900 + (-1 x 21) + (1800 -1900) / 25
His New Rating = 1900 -21 -4 = 1875

The website I mentioned has different examples and includes unrated player
calculations.  But, even if we apply the CxR to the initial Ratings you
(Fergus) have calculated, this system will polish the values over time
and we will have numbers close to those seen in the USCF.

The winning probability is actually irrelevant when using this system.