View Full Version : APA Ratings

09-21-2002, 12:52 AM
I read a lot of references to APA ratings and wonder how accurate they are? I don't play in any leagues and was curious. Let's say you wanted to match up with another league player. Assuming neither was sandbagging and it reflected your actually skill level. Could you use your rating to gamble? Is it very accurate at all in the real world?

J. Price

09-21-2002, 06:22 AM
You might check out my post in the other related topic, "What do ratings really mean in the APA?" But I'll try and answer your questions in further detail here.

I'm not sure about using your rating to gamble, but I think it's a fairly accurate rating system for players across leagues after a certain amount of playing time. If you and your hypothetical opponent have played in leagues long enough for your ratings to level off (a season or two), the relationship between your 6 and his 7 is probably close to the same as between your 6 and a 7 in your league.

The problem is that this rating system is a simplification. If there are 100,000 APA pool players, a perfectly accurate rating system would have 100,000 different ratings. But that's infeasible, and probably not all that desireable. So, there are probably ten thousand in the 6 category and several thousand in the 7 category. There's probably a lot of breathing room for players within rating brackets to win or lose against each other. So a 7 back home might whoop the tar out of a 7 you meet in another state.

The other thing to consider is that it is possible, though unlikely, for a six to beat a seven at a game or even several games, since the rating system is based on a handicap of maybe 4:5 games. But one strength of the system is that it is dynamic, that is, it takes into account that players play differently over time under different conditions. But the statistical validity of the rating system is based on the bell-shaped spread of players over the various ratings. In other words, the majority of players are at the 4 or 5 level, a very small percentage are at the 9 level, ditto for the 1 level. As long as that spread is maintained, the rating system is valid for 9-ball or 8-ball.