FIDE rating calculations

General discussions about ratings.
Roger de Coverly
Posts: 21301
Joined: Tue Apr 15, 2008 2:51 pm

Re: FIDE rating calculations

Post by Roger de Coverly » Wed Jun 29, 2011 10:56 am

Alex Holowczak wrote: I think they're trying to guard against someone scoring 100% v a really weak field. If I had 9/9 v 1500, then my rating could be 2300, since they assign +800 for 1.00. Instead, they would do 4.5*25 = 112.5, so my rating would be 1613.
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That will be worth keeping an eye on, as the International Ratings continue to spread downwards. On paper, deflationary if high percentage performances against weak rated fields become commonplace.

Jonathan Bryant
Posts: 3452
Joined: Sun May 11, 2008 3:54 pm

Re: FIDE rating calculations

Post by Jonathan Bryant » Wed Jun 29, 2011 12:15 pm

Alex Holowczak wrote:
Jonathan Bryant wrote:{PS: I still think FIDE's evaluation of wins against lower rated opponents is a bit mean spirited}
I think they're trying to guard against someone scoring 100% v a really weak field.
I understand the intention, it's just that I think they've gone too far the other way. Obviously you don't want to have somebody having a hugely inflated rating based on a small number of results against weak opposition. That would be ridiculous and make the whole rating system look stupid.

e.g. http://www.guardian.co.uk/football/2011 ... rth-brazil

but wins against people lower rated opponents should count for something. The guys I beat at Sunningdale were only about 5-10 ecf points lower rated than me so it wasn't like they were that much weaker. But for elo they count hardly at all.

On the other hand getting walloped against a 2200 (difference between our ecf grades about 40 points - i.e. four times greater than the games I played at Sunningdale) seems to be much more significant for the elo system.

Sean Hewitt

Re: FIDE rating calculations

Post by Sean Hewitt » Wed Jun 29, 2011 12:29 pm

Jonathan Bryant wrote:I understand the intention, it's just that I think they've gone too far the other way. Obviously you don't want to have somebody having a hugely inflated rating based on a small number of results against weak opposition.

Wins against people lower rated opponents should count for something. The guys I beat at Sunningdale were only about 5-10 ecf points lower rated than me so it wasn't like they were that much weaker. But for elo they count hardly at all.

On the other hand getting walloped against a 2200 (difference between our ecf grades about 40 points - i.e. four times greater than the games I played at Sunningdale) seems to be much more significant for the elo system.
I think it's worth remembering that you are looking at the calulations of your part ratings. Interesting though they may be, they are actually irrelevant when the time will come to calculate your initial rating. That will be based purely on your aggregate result against the rated opponents you played in the events where you achieved your part ratings.

Roger de Coverly
Posts: 21301
Joined: Tue Apr 15, 2008 2:51 pm

Re: FIDE rating calculations

Post by Roger de Coverly » Fri Feb 24, 2012 9:21 am

Chessbase have a new article about 350 and 400 point rules

http://www.chessbase.com/newsdetail.asp?newsid=7941

The ECF's 40 point rule would be equivalent to 320 on the Elo scale, but corresponds to the same expected 89/90% score as the 350 point cutoff. The ECF system being a linear version of the Elo scale, divergences start to appear at the extremities.

Moving from the 350 point rule to the 400 point rule didn't change much. According to the rating table, it moved the expectation from 11% to 8%. Thus for a K=10 player, the gain in rating from beating a much lower rated player changed from 1.1 to 0.8.

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