In a door-to-door fundraising field experiment, we study the impact of fundraising mechanisms on charitable giving. We … approached about 4500 households, each participating in either an all-pay auction, a lottery, a non-anonymous voluntary … contribution mechanism (VCM), or an anonymous VCM. In contrast to the VCMs, households competed for a prize in the all-pay auction …

. This affects the way coalitional bidding impacts auction performance. We study the implications of coalitions of bidders on …, we show that stable coalition profiles tend to consist of excessively large coalitions, to the detriment of both auction …