P = Pbefore + I * (W – We). That’s the equation FIFA use for their world rankings, if that answers your question. But expect it doesn’t, because in our heads it’s always turned into “P before I except after we”.
As you may have gathered from that, the way FIFA calculate their rankings is a bit complex, and can sometimes throw up some weirdness that doesn’t seem to tally with the common sense evidence of our own eyes.
