CeDEx Brown Bag Seminar - Joris Shroeder

Title: How Group Membership Affects Prosocial Behaviour: Evidence From a Nationwide Group Donation Programme Among Blood Donors in Australia

Abstract: Many public goods rely on individuals' cooperation and prosocial behaviour, but sustaining high levels of contributions is often difficult. Laboratory experiments suggest that contributions to club goods (shared only within a group) can be increased by group formation among contributors. We study whether the effectiveness of group formation generalises to high-cost contributions to a real-world public good (shared beyond group boundaries). To do so, we analyse a nationwide group donation programme implemented among blood donors in Australia, which enables donors to form groups with other donors. Using a difference-in-differences design, we show that joining a blood donor group increases yearly donation frequency by approximately 37%, and that the effect levels off over the course of two years. Furthermore, our results show that joining a more active group increases donation frequency more strongly than joining a less active group. Our study contributes to the literature by demonstrating that the strategy of group formation among contributors works in the field, at societal scale, and for the high-cost prosocial behaviour of blood donations. In addition, it informs the practice of blood banks and other organisations dependent on people's prosocial behaviour.