New players: how many games to get a grade?

General discussions about ratings.
Post Reply
Wadih Khoury
Posts: 604
Joined: Sun Jul 12, 2020 8:14 pm

New players: how many games to get a grade?

Post by Wadih Khoury » Sun May 09, 2021 2:47 pm

Under the new ECF rating system, what is the minimum number of games for a rating to be generated? Is it like FIDE (5 games) or is it different?

Brian Valentine
Posts: 574
Joined: Fri Apr 03, 2009 1:30 pm

Re: New players: how many games to get a grade?

Post by Brian Valentine » Sun May 09, 2021 3:57 pm

It depends what an organiser counts as a rating. One game is enough to get a number, see this one for instance:

https://www.ecfrating.org.uk/v2/new/lis ... de=326051D

Dragoljub Sudar
Posts: 165
Joined: Wed Jun 16, 2010 10:34 pm

Re: New players: how many games to get a grade?

Post by Dragoljub Sudar » Wed Oct 06, 2021 5:36 am

My club's new members will begin playing OTB rated standard play games in the bottom division of our league next week, so their opponents could also be first time OTB players. They have asked how soon will they get a published rating? I expect them to be playing a league game every two to three weeks, against rated and unrated players.
How volatile will their ratings be initially and is there an equivalent of an 'F' grade?

Roger de Coverly
Posts: 21291
Joined: Tue Apr 15, 2008 2:51 pm

Re: New players: how many games to get a grade?

Post by Roger de Coverly » Wed Oct 06, 2021 9:57 am

Dragoljub Sudar wrote:
Wed Oct 06, 2021 5:36 am
They have asked how soon will they get a published rating?
The intention of the switch to Elo style ratings was to permit monthly calculations. the return of Congresses suggests they've got this working. The recent Northumbria Open finished on August 30th and the results were in the ECF ratings published 1st September.

Provided the club or league report results promptly to the ECF rating system, I believe the intent is that something will show up at the start of the next month. In the proposals it was envisaged that the initial rating would contain a dummy drawn game. This would have a similar effect to online servers that start everyone off at the same rating with the first few games moving the rating all over the place.

If you can find any previously unrated players in the grading database examination of the calculations should reveal how it works in practice. They may be using "the rule of 400* to calculate when fewer than a stated minimum have been played. Rule of 400 is that you add all the ratings of opponent plus 400 times the excess of wins over losses and then divide by the game count.

There are two ratings published every month. One is what was calculated with the information available on the first day, the other is a recalculation based on updated information. I expect the second figure may change as new data on unrated players becomes available, also affecting their opponents.

Roger de Coverly
Posts: 21291
Joined: Tue Apr 15, 2008 2:51 pm

Re: New players: how many games to get a grade?

Post by Roger de Coverly » Wed Oct 06, 2021 10:30 am

Brian Valentine wrote:
Sun May 09, 2021 3:57 pm
It depends what an organiser counts as a rating. One game is enough to get a number, see this one for instance:
The rating audit goes into detail about the dummy opponents, amongst other things.

https://www.ecfrating.org.uk/v2/new/rob ... 9&domain=S

Well before computers were programmed with recursive calculations, it was claimed that graders started new players at 100. The dummy player system is a similar concept.

Angus French
Posts: 2149
Joined: Thu May 15, 2008 1:37 am
Contact:

Re: New players: how many games to get a grade?

Post by Angus French » Wed Oct 06, 2021 12:03 pm

Roger de Coverly wrote:
Wed Oct 06, 2021 9:57 am
The intention of the switch to Elo style ratings was to permit monthly calculations.
Though it was possible to keep the grading system and use rolling 12-month periods to implement monthly grading, no? Also, I think the grading system calculations were simpler and more easily understood.

Brian Valentine
Posts: 574
Joined: Fri Apr 03, 2009 1:30 pm

Re: New players: how many games to get a grade?

Post by Brian Valentine » Wed Oct 06, 2021 12:10 pm

Dragoljub Sudar wrote:
Wed Oct 06, 2021 5:36 am
My club's new members will begin playing OTB rated standard play games in the bottom division of our league next week, so their opponents could also be first time OTB players. They have asked how soon will they get a published rating? I expect them to be playing a league game every two to three weeks, against rated and unrated players.
How volatile will their ratings be initially and is there an equivalent of an 'F' grade?
As stated upthread a rating is what an organiser decides for whatever purposes. An over-the-board rating is available the day after it is submitted looking in the OTB results section based on latest results. Ratings are firmed up on 1st of each month.

Initial rating are volatile. Because of the special treatment of the dummy rating estimates will vary on volatilty. My rule of thumb is that after one result the standard deviation is around 200 falling to around 90 after 9 results.

The old categories have remained (covid adjusted) for the time being. We will come up with something more suitable for Elo at some stage. Ratings with * category (<5 results) should be treaded with a pinch of salt, many would treat category F ratings the same way.

Post Reply