How Do Suggested Donations Affect Charitable Gifts? Evidence from a Field Experiment in Public Broadcasting

Direct mail fundraisers commonly provide a set of suggested donation amounts to potential donors, in addition to the option of writing in an amount. Yet little systematic evidence exists about the causal effects of suggested donation amounts on giving behavior. To this end, we conducted a field experiment on a direct mail solicitation to nearly 15,000 members of three public broadcasting stations. We varied (1) the vector of suggested amounts, and (2) whether the suggested amounts were fixed or varied as a proportion of the individual's previous donation. We find that increasing the vector of suggested amounts by about 20 percent statistically significantly reduces the overall probability of giving by about 15 percent. The overall impact on revenue is less clear, but appears to be somewhat negative. Higher suggested amounts also lead to write in amounts representing a greater proportion of donations. We attribute our result to the apparent cognitive cost of writing in a preferred amount that differs from a suggested amount. A second field experiment, in which we alter only one of the suggested amounts, gives evidence consistent with that theory and with the idea that donors prefer to give round numbers, as we see donors significantly more likely to give amounts of $90 or higher when suggested $100 versus $95.