Why Do People Give? Testing Pure and Impure Altruism

The extant experimental design to investigate warm glow and altruism elicits a single measure of crowd-out. Not recognizing that impure altruism predicts crowd-out is a function of giving-by-others, this design's power to reject pure altruism varies with the level of giving-by-others, and it cannot identify the strength of warm glow and altruism preferences. These limitations are addressed with a new design that elicits crowd-out at a low and at a high level of giving-by-others. Consistent with impure altruism we find decreasing crowd-out as giving-by-others increases. However warm glow is weak in our experiment and altruism largely explains why people give.