I think the way the river call efficiency stat is calculated on chop (tied) pots should be changed. The stat calculates the average return per $1 of river calls and check calls. But when a river call is made that results in a tied pot, it shows no return on the $$ invested, I assume since the pot is split (assuming two players), and therefore no $$ is won on the hand overall. But the call is saving the player's existing 50% equity in the pot which would otherwise be forfeited if they had folded instead. I think it should show a return that reflects that 50% equity retained.
For example, say a pot was $2 total going into the river. Villian bets $1, and hero calls. Both players split the $4 pot, getting back $2 each. Since hero invested $1 on their river call to get back $2, the stat should show a river call efficiency of 2 for that hand.