Originally Posted by sureshs
Won't his rate be 9/11 = 82%? Where does 73% come from?
8/11 =73%. But his rate would 9/11 =82%. You're right. Yet the point remains, increase of 1% from a win, decrease of 8% from a loss. It's asymmetric with respect to wins and loses.
In the OP's example, even though the 'win' comes later, and is a smaller proportion of the total, @ 40% a 'win' causes a greater change than does a 'loss'.