In or out? Crowding effects in public goods with private gifts: Evidence from crowdfunding
利用奖励型众筹平台数据，研究发现项目的排他性显著影响捐赠模式：排他性强的项目（如本地项目、实物产品）呈现更强的拥挤效应（即更多捐赠吸引更多捐赠），而排他性弱的项目（如全球项目、新闻）则出现挤出效应。
How do cumulative contributions influence subsequent giving to public goods that offer private gifts? While prior research has examined contribution dynamics in fundraising, the role of excludability — the property of preventing noncontributors from accessing the good — remains largely unexplored. We use comprehensive data from a reward-based crowdfunding platform to show that the excludability of a project significantly shapes its contribution pattern. We introduce two novel measures of excludability: one based on a good’s inherent characteristics and another derived from the geographic distribution of backer-project distances. Our analysis reveals that more excludable goods (such as local projects and tangible products) exhibit stronger crowding-in effects, whereas less excludable ones (such as global projects and journalism) experience crowding-out effects. Although crowdfunding platforms systematically highlight cumulative contributions, our findings suggest that fundraisers should emphasize this information, particularly for excludable goods, but not for the least excludable ones. • We study crowding effects in crowdfunding for public goods with private gifts. • We find heterogeneity in both crowding-out and crowding-in effects across projects. • Results show that crowding-in effects strengthen as project excludability increases. • Crowding-out prevails only in the least excludable projects.