Strengthening coupons offers by requiring more from the customer

Reports the experiment conducted by a direct mail company to determine whether a free gift offer would generate incremental sales. Finds that packet mailed with a coupon generated more sales than the control packet (no coupon), and finds that the third packet, in which the coupon offer was coupled with a requirement that the customer complete a questionnaire, generated significantly more sales than the coup alone. Claims that further research is required to determine whether the results would be similar for coupons delivered by methods other than direct mail.