Does context matter more for hypothetical than for actual contributions? Evidence from a natural field experiment

Peer Reviewed
1 January 2008

We investigate the importance of the social context for people’s voluntary contributions to a national park in Costa Rica, using a natural field experiment.


This present paper presents results of a natural field experiment – using the terminology of Harrison and List (2004) – in Costa Rica, where we investigate the importance of (1) anonymity with respect to the solicitor and (2) information about the contributions of others. In particular, we quantify and compare these effects for two samples: one based on hypothetical contributions and one on actual contributions. Both the degree of anonymity and provided information about the contributions of others influence subject contributions in the hypothesized direction. We do find a substantial hypothetical bias with regard to the amount contributed. However, the influence of the social contexts is about the same when the subjects make actual monetary contributions as when they state their hypothetical contributions. Our results have important implications for validity testing of stated preference methods: a comparison between hypothetical and actual behavior should be done for a given social context.

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Publication | 1 December 2007