Help includes how to use the online list. Plus other notes, including an explanation of calculations.
Table of Contents
Why are new grades needed?
Grading has been around for about half a century. The idea behind the BCF/ECF system is that a player graded (say) 10 points higher than his opponent would be expected to score 6/10 against that opponent. (Expected percentage score = 50 plus the difference in grades.)
The original lists were quite small, comprising only the strongest players in the country, but within a very few years it was noticed that grades, for no identifiable reason, were gradually slipping. Sir Richard Clarke, who introduced the system, realised that it should be monitored carefully and felt it ought to be corrected if necessary every 4 years. Unfortunately he had not today’s means of analysing data. The number of players has increased enormously since his day, but the basic system has been largely untouched.
One difficulty was that results, even after the overhaul of the system in 1998-1999, were often submitted or stored in a “bundled” form (Player X, Games Y, Points Z) which did not lend itself to detailed analysis. By 2002 the incidence of bundles was much reduced in favour of actual game results (which are now the norm), and by 2005 we had sufficient information to permit analysis over a four-year period. It was then apparent that results did not match the theoretical expectations. Players who outgraded their opponents by 10 points were scoring approximately 58% rather than the expected 60%. The system had become “stretched”.
There may be several separate reasons for grades to inflate, deflate or stretch out, but the main one is very simple: if we don’t play lots of games against opponents who also play lots of games, the list is bound to become gradually stretched. This has been demonstrated by mathematical modelling, but the results cannot easily be summarised in a meaningful way. We are looking at ways of making this information available to those who are interested.
We have now been able to review the system and restore the old standard that a 10 point grade difference gives an expectation of 6/10 and so on. The review has covered much ground. Most grades have changed quite a lot, because the stretching goes back a long way. The effect of the review is the same as would have been achieved by gentle corrections every few years.
Old Grades remain official in 2008-9, with New Grades published only for reference. Starting with the 2009 list, Old Grades will no longer be produced. Old Grades (even 2008) will have no effect on future New Grades.
The process of review will continue so that any future drifting can be corrected.
How have the new grades been calculated?
New Grades were first published in 2008. For the 2009 list the method of calculation has been revised. Calculations have been completely re-done from 2002, with the result that the 2008 grades now listed may not be identical to those shown last year. The major change is to Junior calculations. See ‘Junior Calculations’ at the end of this section.
The intial calculations were on games played from 2002 to 2006. They were not performed season by season, but on the whole four-year period in a single operation.
First it was necessary to establish a pool of sufficiently active players, and to eliminate distorting effects from improving juniors. So all games of players who were juniors in all or part of the period were removed. Players with less than 25 games remaining were then also removed.
The elimination process was repeated till no one had less than 25 games, leaving a core of players who were active enough to give reliable results.
Grades were then calculated iteratively for these players. Using the resulting grades as a starting point, calculations were done for all games in the four-year period to produce 2006 grades for everybody.
Rapidplay grades were calculated in the same way. The 2006 Rapidplay grades were then adjusted so that, on average, adult players with category C or better at both rates of play had the same grade in both.
2007 and 2008 grades
With the 2006 grades established, Standard and Rapid grades were calculated for 2007 and 2008 in the usual way.
Will simply continue the process, using as their starting point the 2008 New Grades already calculated.
Junior Grades become so rapidly out of date that it has been decided to treat juniors, effectively, as new players each year. (See ‘Estimating a starting Grade for an ungraded player’ in the Help page.) A junior’s previous grade is ignored, and his previous-season games will be ignored if he has at least 20 games in the latest season. If he has not, previous-season games are brought forward to bring the total up to a maximum of 20.
This is the current method, as used in the end-August Grading List. The earlier provisional list (11th August) used a maximum of 9 games for grades other than X and A. Using 20 games has made the grades much less volatile. Many junior grades have changed since 11th August, and there will have been some minor effect on a small number of adult grades.
The Grade Categories for juniors have been revised in accordance with the new calculation, as have the junior increments. For both, see the Help page.
What is the effect of changing to new grades?
Standardplay grades around 220 will, on average, remain the same. Below this, grades will go up; and the lower the grade, the more it will go up. Rapidplay grades, on average, will go up more than Standard because they start from a lower base.
On average, changes are as follows:
Adult New Grade = 0.81 x Old Grade + 43
Junior New Grade = 0.84 x Old Grade + 45
Adult New Grade = 0.84 x Old Grade + 44
Junior New Grade = 0.80 x Old Grade + 56
But note that these “formulae” are true on average only, and cannot be applied to individual players. Different players are affected differently.
FIDE = New ECF x 8 + 650
Conversion from other (national) Elo ratings is unchanged:
National Elo = New ECF x 8 + 600
A beneficial side-effect of the switch to New Grades is that it much reduces the number of negative grades (which are actually published as 0).
Negative grades 2009, A – E:
|Old Grades||New Grades|
These are 2009 figures. Old Grades are not published, but have been calculated for purposes of comparison.
Distribution of grades 2009
In these tables, the columns are cumulative. Thus in the first table:
40% of A grades are at least 155; of A and B grades together, 151; of A – C grades, 147 … The bottom row thus represents all published grades.