Alpízar, Francisco, Fredrik Carlsson and Olof Johansson-Stenman. 2008. “Does Context Matter More for Hypothetical Than for Actual Contributions? Evidence from a Natural Field Experiment.” EfD Discussion Paper 08.
Just how important social context is for voluntary contributions is investigated in a natural field experiment, where subjects made either actual or hypothetical contributions to a national park in Costa Rica.
This study found that both anonymity and information about others’ donations influenced contributions, implying that validity testing of stated preference methods needs to include comparisons of hypothetical and actual behavior for given social contexts.