In 1995, Mark E. Glickman developed the Glicko rating system to address (and solve) the problem, that the Elo rating system neglects the reliability of a player's rating. The Glicko system increases the reliability of a rating for a given player based upon the number of games played and the reliability of the other player's ratings. The reliability is decreased based upon the amount of time that has passed since the last rated game.
The Glicko rating system is used on the Free Internet Chess Server (FICS) and was soon adopted by international game associations and by several internet game servers.
In 2000, the Glicko-2 rating system made a further improvement on the Glicko rating system. Glicko-2 recognizes the possibility that a player may suddenly change in strength expressed as repeated results that are inconsistent with his established rating. As a result, the rating will move more quickly and the associated rating uncertainty will increase until the player has more consistent results.
- A short introduction and a detailed paper on the Glicko rating system. (Wayback Machine used due to loss of original website)
- Mathematical derivation of the Glicko rating system as published in Applied Statistics
- A short introduction and a detailed paper on the Glicko-2 rating system. (Wayback Machine used due to loss of original website)
- The USCF Rating System has adopted the Glicko Rating system. (Wayback Machine used due to loss of original website)