View Single Post
Old 01-17-2013, 01:20 PM   #33
Hall Of Fame
Join Date: Jan 2010
Location: Newtown, PA
Posts: 2,591

Originally Posted by schmke View Post
This is the nature of a half point rating system where in theory a half point difference between opponents should result in a 6-0,6-0 match. This is the reason why a quarter point rating system seems attractive.
This is a myth due to one misinterpreted statement by the USTA that is now perpetuated on here endlessly. The fact is that the expected outcome of a match between two players 0.5 apart is not 6-0 6-0. What the statement said is that a 6-0 6-0 match is not unexpected for players with a 0.5 difference. But matches between any two players will have a whole distribution of possible outcomes. If the expected outcome is 6-0 6-0 only 5% of the time (or 1 on 20), then it's still not unexpected, and since there are thousands of matches in the system between players with this ratings difference, seeing some 6-0 6-0 outcomes is normal and expected. They were writing in the context of people who see a 6-0 6-0 outcome and start jumping up and down that that person is automatically misrated or worse, sandbagging. The fact is that the expected outcome (in terms of a mathematical expected value or average) of a match between two players one level apart is probably about 6-2 6-2 or something like that with 6-0 6-0 having enough positive probability that it's not unexpected or unusual to see some in the real results.

I play 4.0. I'm probably near the top of the 4.0 range (I was 14-2 last year but wasn't bumped). I won a match against a 4.0 rated player 6-0 6-0. It was a kid who wasn't bad, but I just happened to get all the games. I also won a match 6-0 6-2 against a 3.5 playing up. The 4.0 kid was a lot better than this guy, but in the course of this match, I happened to lose a couple games. The 6-0 6-0 kid also lost 6-0 6-3 to another college kid who was bumped at the end of the year who can kick my *** all over the court. If we all played a hundred matches, I would probably win 2 or 3 by double bagel against the kid and the other kid would probably win 15-20 by double bagel. That's not how the actual record is, though, and seeing my 6-0 6-0 win in the record is not a sure sign that I am under rated or that my dynamic rating is or should be lower than the other kid who got bumped and who can kick my ***.

You have to be careful about how you interpret statements and expectations keeping in mind that individual match results are a random draw from a distribution and not a fixed measurement of the difference in ratings.
J_R_B is offline   Reply With Quote