A weight loss program provides three follow-up methods to choose from for individuals who went through the program and reached their desired weight: monthly in-person meeting, monthly on-line meeting, and monthly newsletter by mail. In order to assess the effectiveness of the three follow-up methods, the program selects a random sample of 291 individuals who went through the program and reached their desired weight and classifies them according to the follow-up method that they sign-up for. A year later the study finds that 30% of those who chose to sign up for the in-person follow-up method regained more than 5 pounds, 50% of those who chose to sign-up for the online method regained more than 5 pounds and 70% of those who chose to sign-up for the newsletter method regained more than 5 pounds.