40 Incentive programs need a good start. A car-wash place gave one group of customers a free car wash after 8 washes, and everybody got their first stamp after their visit. Group B got a free car wash after 10 car washes, with 3 stamps on the card. Both groups needed to make 7 more trips to get a free wash. 19% of the Group A returned, while 34% of the Group B did.
