- Chess rating system
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A chess rating system is a system used in chess to calculate an estimate of the strength of the player, based on his performance versus other players. They are used by organizations such as FIDE, the US Chess Federation (USCF), International Correspondence Chess Federation, and the English Chess Federation. Most of the systems are used to recalculate ratings after a tournament or match but some are used to recalculate ratings after individual games. In almost all systems a higher number indicates a stronger player. In general, a player's rating goes up if he performs better than expected and down if he performs worse than expected. The magnitude of the change depends on the rating of his opponents. The Elo rating system is currently the most widely-used.
The first modern rating system was used by the Correspondence Chess League of America in 1939. Soviet player Andrey Khachatoruv proposed a similar system in 1946. The first one that made an impact on international chess was the Ingo system in 1948. The USCF adopted the Harkness system in 1950. Shortly after, the British Chess Federation started using a system devised by Richard W. B. Clarke. The USCF switched to the Elo rating system in 1960, which was adopted by FIDE in 1970 (Hooper & Whyld 1992:332).
Contents
Ingo system
The Ingo system was designed by Anton Hoesslinger and published in 1948. It was used by the West German Chess Federation from 1948 until 1992, when it was replaced by an Elo-based system, Deutsche Wertungszahl. It influenced some other rating systems. This is a simple system where a player's new rating is the average rating of his competition minus one point for each percentage point above 50 obtained in the tournament. Unlike most other systems, lower numbers indicate better performance (Harkness 1967:205–6).
Harkness system
The Harkness System was invented by Kenneth Harkness, who published it in 1956. It was used by the USCF from 1950 to 1960 and by some other organizations.
When a player competes in a tournament, the average rating of his competition is calculated. If the player scores 50% he receives the average competition rating as his performance rating. If he scores more than 50% his new rating is the competition average plus 10 points for each percentage point above 50. If he scores less than 50% his new rating is the competition average minus 10 points for each percentage point below 50 (Harkness 1967:185–88).
Harkness rating categories Category Rating range Grandmaster 2600 and up Senior master 2400–2599 Master 2200–2399 Expert 2000–2199 Class A 1800–1999 Class B 1600–1799 Class C under 1600 Example
A player with a rating of 1600 plays in an eleven-round tournament and scores 2½–8½ (22.7%) against competition with an average rating of 1850. This is 27.3% below 50%, so his new rating is 1850 – (10 × 27.3) = 1577 (Harkness 1967:187).
English Chess Federation system
Main article: ECF grading systemThe English Chess Federation (formerly British Chess Federation) Grading System was devised by Richard W. B. Clarke and first published in 1958. Points are scored for every game played in a registered competition (generally, English congresses, local and county leagues, and other team events). A player's grade is calculated by taking the opponent's grade and adding 50 points for a win, subtracting 50 points for a loss, and taking the opponent's grade as it stands for a draw. For grading purposes it is assumed that the opponent's grade is never more than 40 points above or below one's own. The ECF grades approximately 200,000 games a year. The grading season runs from 1 June to 31 May. An ECF grade can be approximated to an Elo rating by multiplying by 8 and adding 600. An ECF grade of 100 is approximately 1400 Elo, while 200 ECF equals 2200 Elo.
Elo rating system
Main article: Elo rating systemThe Elo system was invented by Arpad Elo and is the most common system. It is used by FIDE and other organizations.
FIDE classifies tournaments into categories according to the average rating of the players. Each category is 25 rating points wide. Category 1 is for an average rating of 2251 to 2275, category 2 is 2276 to 2300, etc. For women's tournaments, the categories are 200 rating points lower, so an Category 1 is an average rating of 2051 to 2075, etc.[1]
Elo scales, 1978 Rating range Category 2600+ World Championship contenders 2400–2600 most Grandmasters (GM) and International Masters (IM) 2300–2400 FIDE Masters (FM) 2200–2300 FIDE Candidate Masters (CM), most national masters 2000–2200 candidate masters, experts (USA) 1800–2000 Class A, category 1 1600–1800 Class B, category 2 1400–1600 Class C, category 3 1200–1400 Class D, category 4 below 1200 novices The USCF uses a modification of the Elo system, where the K factor varies and there are bonus points for superior performance in a tournament. The USCF classifies players according to their rating (Just & Burg 2003:259–73). USCF ratings are generally 50 to 100 points higher than the FIDE equivalents (Just & Burg 2003:112).
USCF rating categories Category Rating range Senior master 2400 and up National master 2200–2399 Expert 2000–2199 Class A 1800–1999 Class B 1600–1799 Class C 1400–1599 Class D 1200–1399 Class E 1000–1199 Class F 800–999 Class G 600–799 Class H 400–599 Class I 200–399 Class J 100–199 Example
Elo gives an example of calculating the rating of Lajos Portisch, a 2635-rated player, in an actual tournament of 16 players, and scored 10½ points. First the difference in rating is calculated for each other player, subtracting the other player's rating from Portisch's rating. Then the expected score against each player is determined from a table, based on this rating difference. For instance, one opponent was Vlastimil Hort, who was rated at 2600. The rating difference of 35 gave Portish an expected score of 0.55. The expected score is summed for each opponent, giving Portisch a total expected score of 9.66. Then the formula is:
- new rating = old rating + K×(W-We), where K=10, W=actual score, and We=expected score.
So 2635+10×(10.5–9.66)=2643.4, Portisch's new rating (Elo 1978:37).
Linear approximation
Elo devised a linear approximation to his full system. With that method, a player's new rating is his old rating plus K×(W-L)/2 plus K/(4C) times the sum of Di, where C=200, K=32, each Di is the opponent's rating minus the player's rating, W is the number of wins, and L is the number of losses (Elo 1978:28–29).
The example of Portisch with K=10, with the sum of the rating differences being 1620 is:
The USCF used a modification of this system to calculate ratings after individual games of correspondence chess, with a K=32 and C=200.[3]
Glicko rating system
Main article: Glicko rating systemThe Glicko system was invented by Mark E. Glickman as an improvement of the Elo system. The Glicko-2 system is a refinement and is used by the Australian Chess Federation and some online playing sites.
USA ICCF system
The ICCF U.S.A. used its own system in the 1970s. Now it uses the Elo system.
Deutsche Wertungszahl
Main article: Deutsche WertungszahlThe Deutsche Wertungszahl system replaced the Ingo system in Germany.
Chessmetrics
Main article: ChessmetricsThe Chessmetrics system was invented by Jeff Sonas. It is based on computer analysis of a large database of games and is intended to be more accurate than the Elo system.
History
- 1933 – The Correspondence Chess League of America (now ICCF U.S.A.) is the first national organization to use a numerical rating system. It chooses the Short system which clubs on the west coast of the US had used. In 1934 the CCLA switched to the Walt James Percentage System but in 1940 returned to a point system designed by Kenneth Williams.
- 1942 – Chess Review uses the Harkness system, an improvement of the Williams system.
- 1944 – The CCLA changes to an improved version of the Williams system devised by William Wilcock. A slight change to the system was made in 1949.
- 1946 – The USSR Chess Federation uses a non-numerical system to classify players.
- 1948 – The Ingo system is published and used by the West German Chess Federation.
- 1949 – The Harkness system is submitted to the USCF. The British Chess Federation adopts it later and uses it at least as late as 1967 (Harkness 1967:184).
- 1950 – The USCF starts using the Harkness system and publishes its first rating list in the November issue of Chess Life. Reuben Fine is first with a rating of 2817 and Sammy Reshevsky is second with 2770 (Lawrence 2009).
- 1959 – The USCF names Arpad Elo the head of a committee to examine all rating systems and make recommendations.
- 1961 – Elo develops his system and it is used by the USCF (Harkness 1967:184). It is published in the June 1961 issue of Chess Life (Elo 1978:197).
- 1970 – FIDE starts using the Elo system. Bobby Fischer is at the top of the list (Elo 1978:68,89).
- 1978 – Elo's book (The Rating of Chessplayers, Past and Present) on his rating system is published.
- 1993 – Deutsche Wertungszahl replaces the Ingo system in Germany.
- 2001 – the Glicko system is published.[4]
- 2005 – Chessmetrics is published by Jeff Sonas.[5]
See also
- Chess engine rating lists
- Sports rating system
- List of FIDE chess world number ones
Notes
- ^ FIDE Handbook, Section B.0.0, FIDE web site
- ^ Elo's book has the incorrect 2645.75. This calculation also uses K=10.
- ^ USCF CC
- ^ Glickman website
- ^ Chessmetrics website
References
- Elo, Arpad (1978), The Rating of Chessplayers, Past and Present, Arco, ISBN 0-668-04721-6
- Harkness, Kenneth (1967), The Official Chess Handbook, McKay
- Hooper, David; Whyld, Kenneth (1992), The Oxford Companion to Chess (2nd ed.), Oxford University Press, ISBN 0-19-280049-3
- Just, Tim; Burg, Daniel B. (2003), U.S. Chess Federation's Official Rules of Chess (5th ed.), McKay, ISBN 0-8129-3559-4
- Lawrence, Al (February 2009), "Ratings, Rules, and Rockets: USCF's 2nd decade: 1949–1958", Chess Life 2009 (2): 9
External links
Categories:- Chess rating systems
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