Post
by Mike Gunn » Thu Apr 24, 2008 6:33 pm
This is what Sir Richard Clarke wrote about the BCF grading scheme in 1969 (it is part of a longer article where he also discusses other grading schemes).
"The B.C.F. Grading System
The B.C.F. scheme followed Harkness. As soon as news of this plan reached here, the B.C.F. Development Committee began to consider the possibility of a grading system: we did not then know of the existence of the Ingo-system. I had published an article in the April, 1953, "B.C.M." on the grading of grandmasters; so then a sub-committee of Gilchrist, Buckle, Wade, and myself was set up, reported in September, 1953, and led to the first B.C.F. Grading List in March, 1954.
We adopted the Harkness notation and the basic Ingo/Harkness principle. But our situation was different, for play in this country is mainly in team events, and not in tourna¬ments. So instead of treating the tournament as a unit, like Ingo and Harkness, our unit had to be the individual game. We had to aggregate every individual's play, and calculate the average grading number of his opponents, and apply to this the premium or discount according to the difference between his percentage score and 50 per cent. Our system must reckon performance over a specified period, for players' club and county results are in units of the season's play. So we calculate and publish the results once a year, instead of continuously from tournament to tournament. We reckon (and the Americans agree) that one needs thirty games to establish a reliable grading number. We began with a three-year grading period. We quickly reduced it to two years, as we organized the flow of material. Now we grade on a one-year period, where thirty games have been played; and if the number in the year is less, fill in the difference from the previous year's performance.
When there is enough material to grade large numbers on one year's play, there is advantage in having a specified period. In the Ingo and U.S.C.F. systems, the period covered is different for every player, and is indeterminate. The grading numbers as published are very up-to-date for very active players; but for those who play less often the figure will represent performance over many years. Thus, the regular official list will be a mixture of very short periods for very active players and quite substantial periods for those who play less.
The B.C.F. scheme has graded huge numbers of players since 1954. The number appearing in the B.C.F. and Union lists, down to grade 11b, is of the order of 3,000. This is the tip of the iceberg: there are four times as many who play in a season but not enough to qualify;and the total number on the graders' books is about 20,000. Our operations are decen¬tralized, and we rely entirely on the devoted work of scores of graders and sub-graders.
After ten years' experience, we conducted a major review. The numbers in the upper grades were falling, and we needed to check whether this was a true trend or whether there was an inherent deflationary tendency: again, there was evidence of a growing regional imbalance, the North appearing to be undervalued and the West overvalued in relation to the South and Midlands. The Grading Committee's review took some years, and the reforms have been introduced as they came.
We decided that there was some downward bias in the system. The main difficulty was that the huge increase in junior play had introduced an element of deflation. In our system, the total strength of each player's opponents is the sum of their last year's grading numbers. If a large proportion of the players is improving fast, their opponents' strengths will be under¬estimated. The juniors' grading numbers are not depressed: the damage is to the grading numbers of the people who play against there. We also found that some of the regions were handling new entrants differently. Adjustments have been made, and review will be done oftener in future.
The hard core of British players who play year after year and are the backbone of club and county chess is remarkably small. Much of the total of serious play consists of people who come in and play for a year or two and then drift away, and of school and university players who drop out when they start business. The rapid turnover of players makes grading very difficult, particularly of juniors. We have improved our practice as a result of the review, but we are not yet certain that we have compensated enough against the inherent deflationary characteristics of these systems.
Another possible deflation results from the invalidity of the Ingo/Harkness/B.C.F. system where there is a big difference between the strength of the players. When a man with grading number X beats one with Y, he scores 50 + Y, which can be expressed as 50 + X — (X — Y). If the difference between X and Y is 50, the stronger player gains nothing for winning, but is debited by getting X — 50 and X — 100 for a draw or a loss. If the difference exceeds 50, the weaker player actually gains (and the stronger loses) even if the stronger wins the game. Ingo and B.C.F. therefore omit games where the difference exceeds 50 whenever the stronger player wins. This is inevitable, but it is unfair to the stronger, who is on a "heads you win, tails I don't" fork.
The practical seriousness of this defect depends upon how often people with differences of 50 or more—six grades—play against one another. When B.C.F. grading began, it did not happen often, which was one reason why we accepted the anomaly. With the growth of the Swiss System, it is now more frequent. Nevertheless, our estimates show that this cannot be a serious reason for deflation, much less important than the under-valuation of juniors. We could in fact virtually eliminate the anomaly by treating all differences between players' gradings of over 40 points as if they were 40 points; but we decided that the added com¬plexity of calculation for our graders outweighed the benefits from removing this anomaly. But we may revert to this later.
So the B.C.F. system is starting on its second fifteen years. It can now be regarded as satisfactory for its real purpose, which is the grading of thousands of players in a great variety of kinds of competition."