Originally posted by willpeet
Is it just me or does my rating always go down twice as fast when I lose as it goes up when I win
I just lost to a player that was 21 points lower than I was and lost 17 points out of my rating. Someone needs to explain this to me.
It is just you. This is copied from the FAQ.
Players are rated using the following formula:
New Rating = Old Rating + K * (Score - Win Expectancy)
K is a constant (32 for 0-2099, 24 for 2100-2399, 16 for 2400 and above)
Score is 1 for a win, 0.5 for a draw and 0 for a loss.
The Win Expectancy is calculated using the following formula :
Win Expectancy = 1 / (10^((OpponentRating-YourRating)/400)+1)
So in your case, assuming your opponent is rated the same, it would come down to this:
Win Expectancy = 1 / (10^(0/400) + 1) = 1 / (10^0 + 1) = 0.5
New Rating = Old Rating + 32 * (0 - 0.5) = Old Rating - 16
And when your opppnent is rated lower, than you will lose more than 16. So giving the rating difference of 21 points, do the math yourself, and you will find out that 17 is the right amount.