Rene Bekkers. 2007. "Measuring Altruistic Behavior in Surveys: The All-or-Nothing Dictator Game." Survey Research Methods, Vol 1, No 3 (open access link here). In surveys, respondents are often given some kind of compensation for their participation. This survey did so as well, but Bekkers also gave respondents the opportunity to donate their payment to a charity rather than keep it for themselves. Here is the abstract:
A field study of altruistic behaviour is presented using a modification of the dictator game in a large random sample survey in the Netherlands (n=1,964). In line with laboratory experiments, only 5.7% donated money. In line with other survey research on giving, generosity increased with age, education, income, trust, and prosocial value orientation.
Bekkers's method here also differs from common dictator game approaches in that the subjects were allocating "earned" endowments rather than windfall endowments. Past research suggests that such determinants of "asset legitimacy" affect what subjects do with their endowments. Note again that it is the survey process itself that allows for this approach to be taken. Of course, since there is no variation in this treatment, we are limited in how much we can learn about such phenomena. Maybe that was a missed opportunity?
In a complementary analysis of self-reported contributions to charities, Bekker follows Smith, Kehoe, and Cremer (1995) ("The private provision of public goods") in using 2SLS to estimate correlates of giving conditional on having given at all. But he claims to have assigned some kind of randomized treatment in the survey that was used to satisfy the exclusion restriction for the first stage of 2SLS. There seemed to be a bit of hand waving on this, and results from the first stage are not included in Table 2. I found this presentation of 2SLS results to be too vague.