New Rating Bonus Point Formula
Today, a new rating bonus point formula became effective. It was adopted at the April 2012 Governors Meeting and the software change was done by Vincent Chow and went live today. Below is the formula and the text of the motion put before the Governors Meeting. The next CFC bulletin will contain an article including some examples.
BONUS 1 = Rmax BONUS *a*Ke
BONUS 2 = b*RATING CHANGE BONUS*(Rnew – Rold – THRESHOLD)*Ke
TOTAL BONUS = BONUS 1 + BONUS 2
a = 1 if the new rating is at an all time high, 0 otherwise;
b = 1 if Rnew > Rold + Threshold, 0 otherwise;
Threshold = RtgChangeThreshold*Ke*sqrt(n) where n is the number of games played; no bonus points are awarded if less than 4 games are played;
Ke is the ratio of the player's K factor to the K factor used for players rated under 2200; For the CFC rating system, K=32 for players under 2200 and K=16 for players at or over 2200;
Rnew is the post-event rating and Rold is the pre-event rating;
and RatingMaxBonus, RtgChangeBonus, and RtgChangeThreshold are constants with the following values:
RatingMaxBonus = 20; RtgChangeBonus = 1.75; RtgChangeThreshold = 13.
The numerical values in the bonus point equation may be adjusted from time to time by the Rating Auditor as deemed necessary and in consultation with the CFC Executive
Reason for Motion:
The proposed formula is based on detailed analysis of the existing tournament data base from 2006 to 2011 and is distilled from the examination of numerous options. It does a superior job of injecting rating points, i.e. when modelled, it generated ratings that more closely predicted actual game results than the existing system.
There were concerns that the existing formula awarded disproportionate bonus points to a small group of high rated players. The proposed formula improves this.
The rating system is inherently deflationary. Care was taken to select a formula that minimizes the effects of inflation and deflation.
The proposed formula mitigates the problem of under-rated juniors by awarding bonus points to players achieving new personal high ratings and by awarding a generous bonus to exceptional performances. These criteria are very common among juniors.
Detailed examination of the methodology leading to this proposal can be found at:
Treasurer, Chess Foundation of Canada
CFC Rating Auditor