Doctoral Dissertation Research in Economics: Increasing Charitable Donations Using Subsidies: Theory and Experiments

本研究探讨了如何以及在多大程度上使用捐赠补贴来增加慈善捐赠。美国政府根据税法为捐赠提供补贴，使符合条件的捐赠免税，有效地为捐赠者提供与其边际税率相等的退税。这些补贴降低了捐助者面临的捐赠价格。另一种补贴捐赠的方法是“匹配”捐赠者的捐款。这是慈善机构最常用的一种补贴方式。通常情况下，慈善机构会与一位富有的捐赠者进行协调，这位捐赠者同意以某种预定的比率向慈善机构提供相应的捐款。例如，捐赠者向慈善机构每捐赠一美元，富有的捐赠者可能会同意额外提供一美元，使慈善机构收到的捐款总额为两美元。与回扣一样，匹配降低了捐赠者面临的捐赠价格。事实上，对于任何给定的回扣，都有一个相应的匹配率，产生相同的给予价格。如果回扣和火柴产生相同的赠送价格，它们就被称为价格相等。与直觉相反，先前的研究发现，捐赠者对价格相等的回扣和匹配的反应并不相同。相反，在保持捐赠价格不变的情况下，捐赠对匹配的反应明显高于回扣。这意味着，重组美国的税收制度，提供火柴补贴，而不是回扣补贴，可以显著增加慈善捐款。然而，这项研究提出了新的证据，表明匹配可能不会像以前的研究中报道的那样优于回扣，特别是在税收方面。通过新颖的实验，研究人员研究了个人对捐赠补贴的反应，以及行为如何根据筹款人的特点而变化，为决策者和对增加捐赠感兴趣的慈善机构提供了有价值的指导。这项研究分为两个项目。第一个项目通过实验室实验比较返利和匹配价格弹性。先前在实验室环境中比较回扣和匹配的研究使用了实验设计，其中价格相等的回扣和匹配产生了不同的预算集，这可能会使价格弹性估计产生偏差。在这项研究中，研究者开发了一种新颖的实验设计，其中退税和匹配是在税收框架内提出的，价格相等的退税和匹配的预算集是相同的。本实验解决了以往研究中存在的预算集问题，与税收政策直接相关。我们还进行了其他实验，以进一步研究驱动捐助者对补贴反应的潜在机制，并深入了解实验设计对观察到的行为的影响程度。第二个项目从理论和实验两方面调查了筹款人特征的差异如何影响捐赠者对匹配率变化的反应。建立了一个包含筹款人特征的理论模型，允许匹配价格弹性在不同的筹款人之间变化。两个实验被用来检验模型的理论预测。第一个实验外源性地改变了捐赠者捐赠匹配的概率。第二个实验通过募捐者的外生性变化间接地改变匹配的概率。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This research examines how, and to what extent, subsidies for giving can be used to increase charitable donations. The U.S. government provides subsidies for giving using the tax code, by making qualifying donations tax-exempt, effectively providing donors with a rebate equal to their marginal tax rate. These subsidies lower the price of giving faced by donors. An alternative method of subsidizing donations is to “match” donors’ contributions. This is the most common type of subsidy used by charities. Typically, charities coordinate with a wealthy donor who agrees to match donations to the charity at some predetermined rate. For example, for every dollar a donor provides to the charity, the wealthy donor may agree to provide an additional dollar, making the total donation received by the charity two dollars. Like rebates, matches lower the price of giving faced by donors. In fact, for any given rebate, there is a corresponding match rate that produces the same price of giving. If a rebate and a match produce the same price of giving, they are said to be price equivalent. Counterintuitively, previous research has found that donors do not respond equally to price-equivalent rebates and matches. Instead, holding the price of giving constant, donations are significantly more responsive to matches than rebates. This implies that restructuring the U.S. tax system to provide match subsidies rather than rebate subsidies could significantly increase charitable donations. However, this research presents new evidence suggesting that matches may not outperform rebates to the extent reported in previous studies, particularly in the context of taxes. Using novel experiments, the researchers examine how individuals respond to subsidies for giving and how behavior varies depending on the characteristics of the fundraiser, providing valuable guidance to policymakers and charities interested in increasing donations. This research is separated into two projects. The first project compares rebate- and match-price elasticities using laboratory experiments. Previous studies comparing rebates and matches in laboratory settings have used experimental designs in which price-equivalent rebates and matches produce disparate budget sets, potentially biasing price-elasticity estimates. In this study the investigators develop a novel experimental design in which rebates and matches are presented within a tax framework and the budget sets for price-equivalent rebates and matches are identical. This experiment resolves the budget set issue present in previous studies and is directly relevant for tax policy. Additional experiments are conducted to further examine the underlying mechanisms driving donors’ responses to subsidies, as well as to provide insights into the extent to which experimental design affects observed behavior. The second project investigates, both theoretically and experimentally, how differences in fundraiser characteristics affect how donors respond to changes in the match rate. A theoretical model of giving incorporating fundraiser characteristics is developed, allowing for match-price elasticities to vary across heterogeneous fundraisers. Two experiments are used to test the theoretical predictions of the model. The first experiment exogenously changes the probability with which a donor’s donation is matched. The second experiment indirectly varies the probability of being matched by exogenously changing characteristics of the fundraiser.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.