1. 5. Assume that a charity hired you to improve its results on donations. You decide to mail letters asking for donations. You use three different types of letters:

Letter A: Control—standard letter asking for money.

Letter B: “Once and Done”—standard letter but with a statement at the front noting that: “Make one gift now and we’ll never ask for another donation again!”

Letter C: Soft “Once and Done”—an upfront statement of: “It takes only one gift to save a child’s life forever.”

The results are as follows:

Letter B (“Once and Done”) raises much more money than Letter A (Control): In most cases, at least double.

Letter C (Soft “Once and Done”) raises more money than Letter A.

Letter B raises about 50 percent more money than Letter C.

Of the concepts we have discussed in the chapter—social pressure, altruism, and herding—which do you think is most responsible for the success of treatment B?