How the ratings systems work
Resolution
Ratings are available for Chess, Go, Reversi, Checkers, Backgammon, Hearts, Pinochle, Spades, Euchre, Cribbage, Canasta, Sheepshead, Gin, Word Racer, Dominoes, Chinese Checkers, Literati, Go Fish, Dots, Naval Command, Pool, Go Stop, Graffiti, Toki Toki Boom, and Yahoo! Towers. All ratings, except Backgammon, are based on the rating system of the USCF (U.S. Chess Federation). Backgammon uses the rating system of FIBS (First Internet Backgammon Server). When you create a table in these games, you have the option of choosing whether you want the game to be rated or not. Your ratings will change as you win and lose rated games.
The amount your rating changes depends on the difference between your rating and your opponent's rating. Note: Your rating might go down if you play someone who has a significantly lower rating than you. Backgammon rating calculations also incorporate the length of the match. The longer the match, the greater the rating change.
Partner games (Pinochle, Euchre, Canasta, Spades, and Dominoes) have additional rules to account for partnerships.
The "free-for-all" games (Hearts, Literati, Mahjong, and Sheepshead) have additional rules for calculating ratings.
Ratings for Word Racer and Graffiti are similar to the free-for-all games. The difference is your rating is calculated against all players at your table, not just the winner. For example, if you come in 4th out of 8, your rating will reflect losses against the players finishing 1st, 2nd, and 3rd and will reflect wins against the players finishing 5th, 6th, 7th, and 8th.
Chinese Checkers, Go Fish, and Dots use a straightforward extension of the USCF system to support games with more than two players.
In Go Stop, the ratings are calculated over three hands. At the completion of these three hands, your score/money for those three hands is calculated and the overall winner is determined. The final calculation is like that of Hearts and the other free-for-all games.
Yahoo! Towers uses the same rating system as Chinese Checkers. The only difference is that since it's a partnership game, your rating and your partner's rating are averaged together, and then the rating calculations are made.
Other items of interest: