Some Interesting Mathematics. Alexei Shirov: "The Rating System Needs Amending Urgently"

Время публикации: 10.04.2015 18:33 | Последнее обновление: 10.04.2015 21:09

Grandmaster Alexei Shirov believes that the system for calculating ratings for classical, rapid and blitz chess needs changing as soon as possible. He wrote about this on his Facebook page. 

"It's just ridiculous that a classical chess game (at least between adult grandmasters) is calculated by K=10 while a rapid or a blitz game (there could easily be some 20 blitz games a day while very few players play more than 11 classical games a month) by K=20. K=10 for classics could make sense in times when rating was calculated twice a year but not now". 

Let us recall the importance of the k-factor. Chess ratings are calculated using a system developed many years ago by Professor Arpad Elo. 

In this formula:
- the new rating Player A gets as a result of a game against Player B;
- Player A's rating at the start of the game;
- the actual number of points scored by Player A in this game;
- the mathematical expectation of the number of points Player A should score in a game against Player B (given by a separate formula) 
- the coefficient Shirov is discussing.

Under current rules, К=10 for players whose rating has ever (even just once) exceeded 2400; К=20 for players who have never exceeded 2400; К=40 for new players, who have not yet played 30 rated games, and also players under the age of 18 and who have not exceeded 2300; К=20 for all rapid and blitz games.

Shirov suggests that the main K-factor for classical chess should be К=20; for those cases where the coefficient is currently less than 15, he suggests it should be K=30; and retain К=40 for all other cases. For rapid games К=15, and for blitz К=10, in both cases regardless of the player's age or rating.

"With this system ratings changes in classical, rapid and blitz chess would at least have a certain similarity", - concludes the Grandmaster. In Shirov's words, this proposal is the result not only of his own thoughts, but also those of Michal Krasenkow and various others.

Shirov is not the only Grandmaster who feels the rating system should be amended. Recently, we published a similar article by Czech Grandmaster, David Navara.     


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