van Diepen, M., Donkers, B. and Franses, P.H. (2009). Does Irritation Induced by Charitable Direct Mailings Reduce Donations? International Journal of Research in Marketing, 26(3):180--188.

Charities rely mainly on direct mailings to attract the attention of potential donors. Individuals may feel irritated by these mailings, in particular when they receive many mailings. This might harm the revenues charities receive from their mailing activities. Moreover, target selection by charities likely results in many mailings being sent to the best donors, and hence they might become most irritated. As such, irritation with direct mailings could well be endogenously determined. To ensure exogenous variation in irritation, we performed a unique controlled field experiment in cooperation with five of the largest charities in the Netherlands. Our analysis reveals that direct mailings do result in irritation, but surprisingly, this irritation affects neither stated nor actual donating behavior.