Ratings system

A simple question: I lost to a player (by checkmate) rated 90 points higher than I am. I lost four points, he or she gained 27. Next game, I defeated a player rated 90 points less than myself: I gained four points; he or she lost seven. What is the logic of this system? Both were checkmate wins; both games were between players who had regular as opposed to provisional ratings.

Why, I can't help but wonder, did my loss earn my opponent 27 points (incredible!) and my win, with a similar ratinsg differential, earn me only seven? I play for fun, not ratings, but I do appreciate fairness in life and in chess.....

His rating deviation is much higher than yours, i.e. he will gain and lose more points until it drops.

Please see http://www.glicko.net/glicko/glicko2.pdf

Rating deviation is a number about how safe a rating is. A completely new player has a high rd and could go up or down more than 300 points after the first game. A player who has thousends of games and keeps playing has a very low rd and therfore wins or loses much less rating points each games.

thanks for the helpful information. did not know this....