ok just read that river call efficiency means per $1 in calls how much money do you make on river calls (so 0 would mean you lose 100% of the time when you call river, 1 would be breakeven, 2 means that for every ). The thing is it's not good to have it too high because it means you should be raising more or perhaps calling more often, plus it seems to be highly dependent on opponent bet sizing. So if an opponent pots it and you call and win the pot I think you would have efficiency of 3? If they go half pot it should be 4 for every win. Of course if they pot it you should call less than if they half pot it, @#%@#%@#% now I'm super-confused, ah well back to pretending it doesn't exist.