This paper analyzes a randomized experiment to shed light on the role of information and social interactions in employees’ decisions to enroll in a Tax Deferred Account (TDA) retirement plan within a large university. The experiment encouraged a random sample of employees in a subset of departments to attend a bene!ts information fair organized by the university, by promising a monetary reward for attendance. The experiment multiplied by more than !ve the attendance rate of these treated individuals (relative to controls), and tripled that of untreated individuals within departments where some individuals were treated. TDA enrollment !ve and eleven months after the fair was signi!cantly higher in departments where some individuals were treated than in departments where nobody was treated. However, the effect on TDA enrollment is almost as large for individuals in treated departments who did not receive the encouragement as for those who did. We provide three interpretations—differential treatment effects, social network effects, and motivational reward effects—to account for these results.
We design a field experiment to test two theories of fund-raising for threshold public goods: Andreoni predicts that publicly announced “seed money” will increase charitable donations, whereas Bagnoli and Lipman predict a similar increase for a refund policy. Experimentally manipulating a solicitation of 3,000 households for a university capital campaign produced data confirming both predictions. Increasing seed money from 10 percent to 67 percent of the campaign goal produced a nearly sixfold increase in contributions, with significant effects on both participation rates and average gift size. Imposing a refund increased contributions by a more modest 20 percent, with significant effects on average gift size.