Paul Cooksey wrote:
However I have not seen an explanation for the way it has been implemented. I question counting back exactly 30 games, how the junior grade calculation is done, and using unpublished grades in January and July. (Mainly the former because I think it creates unnecessary volatility, and the latter two because I think I ought to know the grade of a person I am playing)
Quite possible that these things were necessary, but it would be nice to know why.
The 30 game count back was inherited from the way they do it for rapid-play grades. No-one complained, either because rapid-play is relatively homogeneous being mostly tournaments, fewer players play it, or no one really cares what their rapid-play grade is.
The junior calculation has been that way since August 2009 when it was brought in as a final fix to get the grading revaluation signed off. It wasn't that easy to reverse engineer the source of junior grades until this month with the detail analysis of not just your own results, but also all your opponents. I had struggled to see the source of Junior grades when analysing my 2009, 2010 and July 2011 results by event. I had missed the trick that the grade in the calculation is neither the start period grade, nor the end period grade. It's claimed that if you play a junior who has just the one game, that you always score your own grade. With the download available, I might try to find a practical example to validate this or otherwise.
(edit) There's an earlier discussion partly about count back at viewtopic.php?f=4&t=3252
In effect Council at the 2010 AGM handed the graders a blank cheque as far as methodology for the six monthly development. They used the method already employed for the rapid play grades. (/edit)