OzChess - Australia's Chess Forum - View Single Post

**Z&MLoh** · 03-14-2010, 08:47 PM

Originally Posted by MOZ

First, thank you for the work done to create this ratings analysis.

The underlying population is changing over time.
Some players drop off the active playing list.

Some players join the active playing list

Some players improve their chess playing skill.

I would speculate the third category are taking rating points from the two rating cohorts that seem to be on a down-ward trend.

Moz,
I tested your theory above and you are right ... of course.

Using March 09 data as the basis for comparison,

Code:

1600-1899 group

	Players		Players in Mar-09	Players not in Mar-09
Mar-09	  49		
Sep-09	  59			23			36
Mar-10	  43			20			23

Code:

1300-1599 group

	Players		Players in Mar-09	Players not in Mar-09
Mar-09	  43		
Sep-09	  77			25			52
Mar-10	  68			20			48

03-14-2010, 08:47 PM	#134 (permalink)
Z&MLoh Senior Member Join Date: Nov 2008 Location: Melbourne Posts: 286	Originally Posted by MOZ First, thank you for the work done to create this ratings analysis. The underlying population is changing over time. Some players drop off the active playing list. Some players join the active playing list Some players improve their chess playing skill. I would speculate the third category are taking rating points from the two rating cohorts that seem to be on a down-ward trend. Moz, I tested your theory above and you are right ... of course. Using March 09 data as the basis for comparison, Code: 1600-1899 group Players Players in Mar-09 Players not in Mar-09 Mar-09 49 Sep-09 59 23 36 Mar-10 43 20 23 Code: 1300-1599 group Players Players in Mar-09 Players not in Mar-09 Mar-09 43 Sep-09 77 25 52 Mar-10 68 20 48 Last edited by Z&MLoh : 03-14-2010 at 09:49 PM