Chessmetrics is a system for rating chess players devised by Jeff Sonas.
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.
Moreover, retrospective grading allows him to establish rankings that are unbiased estimates of the "true" relative strengths of players.
[2]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.