|
For Reversi
, the Zone uses the Chess Rating formulas established by the U.S. Chess Federation (USCF). The USCF's rating system divides players up into three rating-point categories. The higher the point category, the lower the cap on points that players can earn from a given game. For more information about the USCF rating system, please see the U.S. Chess Federation's Web site.
Here are the USCF formulas on how to calculate your Reversi
rating points. You begin with 1600 rating points. Your rating points will increase when you win a game and decrease when you lose a game unless you are down to 100 points -- the program will never drop your rating below 100 points.
Rn = Ro + K(W-We)
Where:
Rn is the new rating. Ro is the old (pre-event) rating. K is a constant value based on your rating category. For 0-2099 rating, K = 32.
For 2100-2399 rating, K = 24.
For 2400 rating and above, K = 16.
W is the score in the event. For a win, W = 1.
For a loss, W = 0.
For a tie, W = 0.5.
We is the expected score (Win Expectancy), which can be calculated from the following formula: We = 1/(10(dr/400) + 1)
"dr" equals the difference in ratings.
"K" is a major factor in calculating your rating points. To receive the maximum number of rating points for a single match, challenge and beat a player who has 800 more rating points than you.
If you win a game and your current rating is:
(0-2099), you will receive between 1 and 32 points.
(2100-2399), you will receive between 1 and 24 points.
(2400 and above), you will receive between 1 and 16 points.
If you lose a game, you will lose the above number of points.
If a player falls into a different rating category after playing in a game, the number of points the player won or lost is decreased. This is to minimize the role of luck in the progression up or down and to ensure that players of comparable skill level are steadily being matched against each other. One of the following equations is used to adjust the post-game rating:
|
Pre-game Rating
|
|
Post-game Rating
|
|
|
|
0-2099
|
|
2100-2399
|
|
Ra = 2100 + (Rn - 2100) x 0.75
|
|
2100-2399
|
|
0-2099
|
|
Ra = 2100 + (Rn - 2100) x 1.33
|
|
2100-2399
|
|
2400-3000
|
|
Ra = 2400 + (Rn - 2400) x 0.66
|
|
2400-3000
|
|
2100-2399
|
|
Ra = 2400 + (Rn - 2400) x 1.50
|
Where Rn is the post-game rating and Ra is the "crossing K factor" adjustment. Ra becomes the new post-game rating.
|
