The NBA and other professional sports leagues offer a unique environment in which to study quitting behavior. Decision-makers in pro sports get a lot of continuous, quick, clear feedback on player productivity. Pro basketball is a data-rich environment, with many objective measures of player performance for scoring (points, field goal percentage, free throw percentage), toughness (rebounds and blocks), and quickness (assists and steals). The coach and team management are highly motivated to use the best players in the right situations and, obviously, to win.