How The Elo Rating System Works In Chess: Elo Ratings Explained
Introduction
Most chess players are infatuated with their Elo rating and constantly monitor their rating after each chess game, but what exactly is an Elo rating and what is its significance in chess? The Elo rating system in chess is a fundamental component of competitive chess which is useful for many reasons but mainly because it allows chess players to measure their strength and progress in chess and it also allows chess players to easily find opponents that are closely matched in experience. The history and evolution of the Elo rating system as well as the calculations used to determine a chess players Elo rating in chess are some of the most interesting aspects of chess which will intrigue regular chess players as well as non-chess players. In this article I will cover everything you need to know about the Elo rating system in chess including its origins, evolution, how it is measured and much more.
The Origins And The Evolution Of The Elo Rating System In Chess
The Elo rating system in chess was initially developed in the 1960’s by a Hungarian American physics professor, Arpad Elo which is where the term Elo comes from and is the successor of the previously used Harkness rating system which was created by Kenneth Harkness. The Elo rating system is an improved version of the Harkness rating system which utilises a sophisticated mathematical framework for determining a chess players skill based on probabilities and a dynamically adjusting performance metric.
The Elo rating system in chess is the successor of the Harkness rating system that was developed by Kenneth Harkness during the 1950’s and later adopted by the USCF (united states chess federation). Kenneth Harkness was a chess organiser and former executive director and business manager of the USCF (united states chess federation) from 1952 to 1960. The Harkness rating system was initially developed to assess and assign a numerical value to chess players skills during rated chess games however the system had some limitations which impacted its ability to accurately determine the true skill level of chess players. Some of the main factors that contributed to the Harkness rating system’s inefficiencies as a rating system includes infrequent updates to chess players ratings due to the fact that it updated chess player ratings annually instead of after each chess game which is standard in the Elo rating system, sensitivity to the outcome of individual chess games which resulted in significant changes to chess player ratings and a complex mathematical method of measuring chess player ratings that had to be manually calculated after each chess game which ultimately resulted in an inability to accurately determine a chess players current skill level in real time. The Harkness rating system was also used primarily in the United States and lacked the adoption from the international chess community.
The Elo rating system was developed by Arpad Elo, who was a Hungarian American physics professor, highly skilled chess player and active participant in the USCF (united states chess federation) since its founding in 1939. The Elo rating system was introduced into mainstream chess and adopted by the USCF (united states chess federation) ten years after the release of the Harkness rating system during the 1960’s and was created using an even more sophisticated mathematical framework than was previously utilised in the Harkness rating system. Although the Elo rating systems method of calculating the rating of chess players was much more sophisticated than the Harkness rating systems it was also much more efficient and reliable. Elo ratings are calculated by incorporating mathematical formulas and algorithms which allows chess players to receive ratings that are much more accurate and up to date. One of the main characteristics of the Elo rating system is that much like the beliefs of its creator Arpad Elo, it assumes that a chess players true and current skill level is the sum of that chess players past performance and their current performance in rated chess games. For example, if a chess player has been consistently successful throughout their career in chess but goes through a period of playing chess at a level that is beneath their anticipated levels of success, their rating will drop by a set amount for each chess game depending on the rating of their opponent and the expected outcome of the game which makes it much easier to accurately determine an estimation of their true and current skill level. The Elo rating system was considered to be much fairer and accurate than the Harkness rating system and was later adopted by the world chess federation, FIDE, in 1970.
The Calculations Behind The Elo Rating System
Elo ratings are calculated by issuing chess players an initial rating and an expected score before a chess game. After the chess game chess players are then given an actual score and their Elo ratings are updated accordingly. There are numerous variations to how Elo ratings are calculated in chess depending on the criteria that needs to be met by each chess governing organisation, the most common Elo rating system is based on FIDE’s calculations however other chess governing organisations calculate Elo ratings differently and do not follow Arpad Elo’s methods exactly.
Before a chess game chess players are given a random Elo rating however in most cases, they are given an Elo rating of a thousand and an expected score based on their current estimated skill level which are essential for calculating their final Elo rating. The mathematical formula that’s used for working out a chess players expected score is as follows: E = 1 / 1 + 10(Rb — Ra) / 400 this formula is used to calculate the expected score of the example player A and switching the placement of the rating of player B with the rating of player A in the equation can be used to calculate the expected score of the example player B. The E represents the expected score of the player, Rb represents the initial given rating of player B and Ra represents the initial given rating of player A. The second formula which calculates the updating of each players rating is as follows: NR= Current Rating + K (actual score-expected score), the NR represents the new or updated rating of the player, and the K represents the K factor which is a constant that’s used to determine the impact of the result of the game on each chess players ratings. Each chess governing organisation uses a different number to represent the K factor, but it generally ranges from 10 to 32. A higher K factor results in a much more significant increase or decrease in ratings and is typically used in the chess games of less established chess players whereas a lower K factor results in a less significant increase or decrease in ratings and is typically used in the chess games of more established chess players.
FIDE uses a K factor of 10 for high rated chess players but they also utilise a tiered system depending on the rating of chess players to assign a K factor when calculating their rating increase or decrease. All chess players that are new to FIDE’s database until the completion of events with a total of 30 games under FIDE’s observation, and for chess players under the age of 18 that have maintained an Elo rating of under 2300 will have a K factor of 40 when calculating their new FIDE approved Elo rating, chess players that have consistently maintained an Elo rating of under 2400 will have a K factor of 20 when calculating their new FIDE approved Elo rating and chess players with any published rating of at least 2400 and at least 30 games played in previous events will have a K factor of 10 permanently applied to the calculation of their new FIDE approved Elo rating. The USCF (united states chess federation) used to implement a tiered system of assigning a K factor to calculate chess players ratings which were as follows: a K factor of 32 for chess players with a rating below 2100, a K factor of 24 for chess players with a rating between 2100 and 2400 and a K factor of 16 for chess players with a rating above 2400 however they now use a formula that calculates the K factor depending on the number of chess games played and the chess players rating whilst reducing the K factor for higher rated chess players in chess games with shorter time controls. Online chess gaming sites use various methods to calculate the rating of chess players whilst most use the Elo rating system, others consider it to be outdated and prefer to use more up to date rating systems such as Glicko-1 and Glicko-2 which is a rating system that was created by Mark Glickman.
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