Chessmetrics is a system for rating chess players devised by Jeff Sonas. It is intended as an improvement over the Elo and Edo rating systems.

Implementation

Chessmetrics is a

weighted average The weighted arithmetic mean is similar to an ordinary arithmetic mean (the most common type of average), except that instead of each of the data points contributing equally to the final average, some data points contribute more than others. The ...

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.

Formulas

Performance rating adjustment after tournament: :

Performance Rating = Average Opponents' Rating +  PctScore - 0.50) * 850/code>

Weighting of past tournaments (age is how many months ago the tournament was played):
:100% * (24 - age)

 Reception


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.

The system has also been described as "the most complete and resounding attempt made to determine the best chess player in history". However, the system is more accurate in measuring a player's success in competition than quality of play.Computer Analysis of World Chess Champions
 M.Guid and I.Bratko,  ICGA Journal (Vol 29, No. 2, June 2006, pages 65–73).

 Popularity

The original article on Chessmetrics was published in Chessbase 

ChessBase is a German company that develops and sells chess software, maintains a chess news site, and operates an  internet chess server for online chess. Founded in 1986, it maintains and sells large-scale databases containing the moves of recor ...
 in October 2002. Since then, Chessmetrics has become reasonably well known and features numerous articles in Chessbase 

ChessBase is a German company that develops and sells chess software, maintains a chess news site, and operates an  internet chess server for online chess. Founded in 1986, it maintains and sells large-scale databases containing the moves of recor ...
 and The Week in Chess 




''The Week in Chess'' (TWIC) is a chess news web site. It was founded in 1994 and is based in the United Kingdom.

''TWIC'' has been edited by Mark Crowther since its inception in 1994. It began as a weekly Usenet 






Usenet (),  a portmante ...
.For instance, Chessmetrics articles on Comparison of top chess players throughout history 

Several methods have been suggested for comparing the greatest chess players in history. There is agreement on a statistical system to rate the strengths of current players, called the Elo system, but disagreement about methods used to compare pla ...
 at Chessbase 

ChessBase is a German company that develops and sells chess software, maintains a chess news site, and operates an  internet chess server for online chess. Founded in 1986, it maintains and sells large-scale databases containing the moves of recor ...

Part 1Part 2Part 3Part 4
/ref>

Chess author  John L. Watson has also referred to Chessmetrics numbers.

 See also

* Chess rating systems 
A chess rating system is a system used in chess to estimate the strength of a player, based on their performance versus other players. They are used by organizations such as FIDE, the  US Chess Federation (USCF or US Chess), International Correspon ...


 Notes



 External links


Chessmetrics site

{{Sports rating systems

 Chess rating systems