Transplants of donated stem cells save the lives of many patients with blood diseases. Donation is somewhat painful, but rarely has lasting adverse effects. Patients can accept transplants only from donors with compatible immune systems. Those lacking a sibling match must seek donations from the...

This paper surveys the literature on group selection. I describe the early contributions and the group selection controversy. I also describe the main approaches to group selection in the recent literature; fixation, assortative group formation, and reproductive externalities. -- Altruism ; spite...

We examine how economic incentives affect pro-social behavior through the analysis of a unique dataset with information on more than 14,000 American Red Cross blood drives. Our findings are consistent with blood donors responding to incentives in a standard way; offering donors economic...

A substantial body of research suggests that economists are less generous than other professionals and that economics students are less generous than other students. We address this question using administrative data on donations to social programs by students at the University of Washington....

We conduct field experiments in a large real-world social network to examine why decision-makers treat their friends more generously than strangers. Subjects are asked to divide a surplus between themselves and named partners at varying social distances, but only one of these decisions is...

We conduct field experiments in a large real-world social network to examine why decision-makers treat their friends more generously than strangers. Subjects are asked to divide a surplus between themselves and named partners at varying social distances, but only one of these decisions is...

We examine how economic incentives affect pro-social behavior through the analysis of a unique dataset with information on more than 14,000 American Red Cross blood drives. Our findings are consistent with blood donors responding to incentives in a "standard" way; offering donors economic...

A substantial body of research suggests that economists are less generous than other professionals and that economics students are less generous than other students. We address this question using administrative data on donations to social programs by students at the University of Washington....

Pay-what-you-want schemes can be a useful tool to finance high quality and independent news media without restricting readership, therefore guaranteeing maximum diffusion. We conduct a field experiment with the Italian information site lavoce.info to explore how to structure a campaign in a way...

Pay-what-you-want schemes can be a useful tool to finance high quality and independent news media without restricting readership, therefore guaranteeing maximum diffusion. We conduct a field experiment with the Italian information site lavoce.info to explore how to structure a campaign in a way...