Copied from FAQ files:
How are the ratings calculated?
When you join, you are given a rating of 1200. If, when you joined,
you received a rating of 1000, your rating has now been recalculated
based on a starting rating of 1200.
Currently all completed human vs human games where at least two
moves have been made by each player are rated. Games played
against Rival Online (the computer player) are not rated.
Players are rated using the following formula:
New Rating = Old Rating + K * (1 - Win Expectancy)
K is a constant (32 for 0-2099, 24 for 2100-2399, 16 for 2400 and
above)
The Win Expectancy is calculated using the following formula:
Win Expectancy = 1 / (10^((OpponentRating-YourRating)/400)+1)
The Win Expectancy is used in the rating calculation but is interesting
on its own. For example, the calculation below is for a rating difference
of 200. This shows that if you have a rating 200 points higher than
another player, you can expect to beat them, on average, three times
for each four games played.
Win Expectancy = 1 / (10^(-200/400)+1) = 0.76
Note: ^ = "to the power of", e.g. 2^3=8.
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Or in simple terms: Beat someone better your rating goes up.
Beat a lower ranked player and your rating goes down.
Rhymester
"Or in simple terms: Beat someone better your rating goes up.
Beat a lower ranked player and your rating goes down. "
oops. should read:
"Or in simple terms: Beat someone better your rating goes up by more than 16.
Beat a lower ranked player and your rating goes up by less than 16."
no, if anything then it is where Andrew's mind set is. I merely corrected his statement. You cannot lose points by winning a game.
Yes when you lose it is exactly the opposite, centered around 16. The idea is that a game does not change the total sum of rating
points. You lose/win what your opponent wins/loses (apart from rounding issues that are not clear to me).
