Is a Donor in Hand Better than Two in the Bush? Evidence from a Natural Field Experiment
通过连接不同时间处理的捐赠实验，研究发现先前捐赠者更可能继续捐赠且金额更大，但获取方式至关重要：经济机制吸引的捐赠者比非机制因素吸引的更具持续性。
This study examines why people initially give to charities, why they remain committed to the cause, and what factors attenuate these influences. Using an experimental design that links donations across distinct treatments separated in time, we present several results. For example, previous donors are more likely to give, and contribute more, than other donor types. Yet, how previous donors were acquired is critical: agents initially attracted by an economic mechanism are more likely to continue giving than agents attracted by a nonmechanism factor. From a methodological viewpoint, our study showcases the benefit of moving beyond an experimental design that focuses on short-run substitution effects.