21-10-2011, 10:19 AM
Gary McPheator Wrote:I agree that a rolling grade would not give an accurate reflection of the strengths in the scenario above, it isn't perfect. But neither is the current system, as if you substitute an adult for one of the above juniors then the junior will still be graded 1000 while the adult will have an increased grade.
With regards to deflation, I believe it could be dealt with by drifting adult grades. As adult grades are more stable, it makes sense to keep the points they have in the system at the same level while letting the junior points fluctuate. A weekly drift would be better and more inkeeping with a rolling grade than an end of season adjustment.
In the current system the adult will not be expected to score 50% against the junior. If the junior addition is +120 then the adult will be expected to score 0.337 on every game ie 10.11/30 The junior will genuinely have improved so his grade will go up since he will be expected to score 50% on the arithmetic but in reality will score more than 50%. The adult is stable and his grade will not go down since he has been compensated by the junior bonus points reducing his expected scores.
At the end of the grading period you will have two grades which add up to more than 2000 ie the system will reflect the fact the pool of players has improved in true ability - you have (in theory) grading stability. (The actual level of the additions may not be right but we're just talking of the theory here).
Will you get that with a rolling grade system that doesn't have additions? Wont you just get rapidly deflating grades as the juniors take points unfairly from adults who have not changed their skill level?
"I believe it could be dealt with by drifting adult grades" - not sure what that means, Gary.