Matthew Turner wrote:Richard et al,

Let me try to give an explanation why deflation has occured in the last. I believe the problem is the greater use of computing in the process of grading. Imagine a club competition with two new players A and B and two established players graded 40 and 100

A B 40 100

A X 0 1 0.5

B 1 X 0 0

40 0 1 X 0.5

100 0.5 1 0.5 X

What used to happen was that the local estimated a grade for new players let's say 80.

Player A now gets 30+90+100 = 220 grading points

Player B get 130 +(-10) + 50 = 170

However, (as I understand it) the computer now awards new players a grade to calculate their other results on

Player A win against 40 = 90 plus draw aginst 100 = 100 therefore performance = 95

Player B loss against 40 = -10 plus loss against 100 = 50, therefore performance = 20

For player A's loss against B he can only receive a maximum of 90 less than his 'grade' so gets 5 points. Therefore his total grading points are 185 - a loss of thirty-five.

For player B's win aginst A he can only get a maximum of 90 plus his grade so 110, meaning his total point are 150 - a loss of twenty.

There is nothing wrong with computers, but you do have to understand what they are doing.

This explanation doesn't convince me there has been deflation in the past.

First, its based on the assumption that in the days when graders had to estimate the grades of ungraded players and use them in their calculations, overall they overestimated the true strength of those players. What evidence is there to support this?

Second, if we assume that graders did overestimate the strength of ungraded players in the past, that would have lead to inflation in the grading system while they were doing it. Now they no longer have to do this estimate, there is no longer inflation due to it. That's left us with an inflated grading system.

Third, take your example of 2 graded and 2 ungraded players. Before the event there were 2 graded players and the average grade of all graded players was 70. After the event there were 4 graded players and the average grade of all graded players was 63 (see

http://www.ecforum.org.uk/viewtopic.php?f=4&t=470 for the calculation of this). If we change the results so that B beats the player graded 40 instead of losing, then, after the event, the average grade of all graded players is 77. One set of results causing the overall average grade to go down and another causes it to go up. What evidence is there to show that, in reality, either of these scenarios occurs more often than the other?