Internet Scrabble Club

RATING

• The rating formula is based on the opponent's rating and the score difference. You can win or lose somewhere between 0 and 40 points. Suppose your rating is r1 , and the opponent's is r2. Let w be 1 if you win , .5 if you draw, and 0 if you lose.
After a game, your new rating will be:

```
1
r1 + k  * [w -  ----------------------]
1 + 10 ^ ((r2-r1)/400)
|d|
where, k = 20 + ---
10
|d| - score difference - can have values between 0 - 200
```

• If you're playing a provisional player , k is scaled by (11 - n), where n is one plus the number of games your opponent has played.

• The formula used for provisional players is based on the average rating of his opponents and the number of wins and losses. This formula can have a strange behavior since you can lose points after winning a game if your opponent rating is below average:
m + 133 * ln(w/l)
m - opponents rating average
w - number of wins
l - number of losses

• If both players are provisional there will be no rating change.

• You can see how your rating will be affected before the game starts. Click on the person's name and select [assess] , also you can type 'assess name' in the command mode.