Author: Dann Corbit
Date: 10:50:46 10/27/99
Go up one level in this thread
On October 27, 1999 at 11:47:14, Robert Hyatt wrote: [snip] >If you play someone that far under you, you had better win every game, or else >your rating _only_ can go down. But if they are really that far under you, you will win the expected number on average, and your number will stay the same. Consider the following table: Win expectency for a difference of 0 points is 0.5 Win expectency for a difference of 100 points is 0.359935 Win expectency for a difference of 200 points is 0.240253 Win expectency for a difference of 300 points is 0.15098 Win expectency for a difference of 400 points is 0.0909091 Win expectency for a difference of 500 points is 0.0532402 Win expectency for a difference of 600 points is 0.0306534 Win expectency for a difference of 700 points is 0.0174721 Win expectency for a difference of 800 points is 0.00990099 [snip] Win expectency for a difference of 2000 points is 9.9999e-006 If you play someone one hundred points lower than you, they will get 36% of the points and you will get 64% and your rating will stay the same. If you play someone 200 points lower, you will get 76% of the points and they will get 24% and your rating will stay the same. If you play someone 300 points lower, you will get 85% of the points. If you play someone 400 points lower you will get 91% of the points. At a 500 point difference, you will win 95% of the points. At a 600 point difference, you will get 97% of the points. At a 2000 point difference, you will win 99.99% of the points. In all cases, your rating will stay the same. Playing lower rated players should not (in theory) change your rating at all. The very rare draw or extremely rare loss to a low-rated player will be balanced out by a bazillion wins. On the other hand, games against players hundreds of points beneath you are not really very exciting [imo]. Who would gather around to watch Kasparov play me? If he played Anand or Adams or some highly skilled player, that would be something people want to watch. The reason is that I have basically no chance of winning so the outcome is pretty well known even before we start. So from a point of interest, I don't think it makes a lot of sense to play opponents that are miles beneath. Those that claim your rating can be inflated by choosing opponents are not aware of how the math works. And (let's suppose) that you have played someone ten times and lost them all. You might think that -noplay would be good for you. But look at all the recent SSDF contests where one program had a big lead and suddenly lost it. Without a huge number of games, there is really no way to know what the win expectancy would be, and once we know it accurately, then it will only reflect upon our true rating. [snip]
This page took 0.01 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.