Before revision:  We further find thatthe "luckiest draw" recipients repay 1.5 times more than other recipients, and identify a group norm that luckiest draw recipients should send payment back to the group .
After revision:  We further find thatthe "luckiest draw" recipients repay 1.5 times more than other recipients, and identify a group norm according to which the luckiest draw recipients should send payment back to the group .