Chessmetrics
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Chessmetrics is a system for rating chess players devised by Jeff Sonas. It is intended as an improvement over the Elo rating system.
Implementation
Chessmetrics is a weighted average of past performance.[1] 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.
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)
Perceived advantages
In 2006 economists Charles C. Moul and John V. C. Nye used Chessmetrics to determine the "expected" results of games, and wrote:
Ratings in chess that make use of rigorous statistics to produce good estimates of relative player strength are now relatively common, but comparing ratings across different time periods is often complicated by idiosyncratic changes (cf. Elo, 1968 for the pioneering discussion). Sonas uses the same rating formula throughout our sample and updates this rating monthly instead of annually, as is more common. Moreover, retrospective grading allows him to establish rankings that are unbiased estimates of the "true" relative strengths of players.[2]
Perceived disadvantages
Chessmetrics can only be used to compare the level of a player against their peers; it is not appropriate to use Chessmetrics to compare players of different era. For example, GM John Nunn has highlighted the absurdity of attempts to compare the objective playing strengths of players from different eras. He used the example of Hugo Suechting, world ranked 27 and rated 2559 by Chessmetrics in 1911, after the Elite tournament in Karlsbad. An analysis of Suechting's games from that period suggested to Nunn that his level of play was at best 2100 by today's standards.[3]
Chessmetrics site's last update was March 26, 2005.
Popularity
The original article on Chessmetrics was published in Chessbase in October 2002.[4] Since then, Chessmetrics has become reasonably well known, due to numerous articles in Chessbase and The Week in Chess.[5]
Chess author John L. Watson has referred to Chessmetrics numbers,Cite error: The opening <ref> tag is malformed or has a bad name (see the help page). and Chessmetrics has been cited in at least two academic papers.[2][6]
See also
Notes
- ^ Chessmetrics formulas page Archived 2011-08-09 at the Wayback Machine
- ^ a b Charles C. Moul and John V. C. Nye (May 2006). "Did the Soviets Collude? A Statistical Analysis of Championship Chess 1940–64". The Social Science Research Network. SSRN 905612.
{{cite web}}:|access-date=requires|url=(help); Missing or empty|url=(help) Full article freely available via links on the cited web page. - ^ Nunn's criticism Archived August 13, 2011, at the Wayback Machine
- ^ Cite error: The named reference
Sonas2002BetterThanElowas invoked but never defined (see the help page). - ^ For instance, Chessmetrics articles on Comparison of top chess players throughout history at Chessbase: Part 1 Part 2 Part 3 Part 4
- ^ Computer Analysis of World Chess Champions, M.Guid and I.Bratko, ICGA Journal (Vol 29, No. 2, June 2006, pages 65–73).