assuming everything else were controlled for (and i have no idea how you do that) then you'd expect the "noise" in num-wallets-returned to be about sqrt(num-wal

assuming everything else were controlled for (and i have no idea how you do that) then you'd expect the "noise" in num-wallets-returned to be about sqrt(num-wallets-returned). in other words, in a city where the "real" rate is 4 returned, you expect to see that number varying by about 2 each time, so maybe 4, 2, 7, 3, 1... so the results here really don't mean much.