Chessmetrics
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Chessmetrics is a system for rating chess players devised by Jeff Sonas.
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[edit] Implementation
Chessmetrics is a weighted average of past performance. The score considers a player's win percentage against other players weighted by the ratings of the other players and the time elapsed since the match. A 10% increase in performance is equivalent to an increase of 85 rating points.
The weighting of previous matches digresses linearly from 100% for just-finished matches to zero for matches conducted more than two years ago.
[edit] Formulas
Performance rating adjustment after tournament:
- Performance Rating = Average Opponents' Rating + [(PctScore - 0.50) * 850]
Weighting of past tournaments (age in months):
- 100% * (24 - age)
[edit] Perceived advantages
Advocates of Chessmetrics claim that contrary to the Elo rating system, it does not suffer from rating inflation and is intended to allow to compare the ratings of players from different eras.
