This is an online appendix to Lacetera, N., Macis, M., and Slonim, R., 2013: “Rewarding Volunteers? A Field Experiment …

We run a public good experiment in the field and in the lab with (partly) the same subjects. The field experiment is a … true natural field experiment as subjects do not know that they are exposed to an experimental variation. We can show that … subjects' behavior in the classic lab public good experiment correlates with their behavior in the structurally comparable …

' purchase decisions (whether to buy, and if so how much to pay) in a natural experiment at an online music store with PWYW …%. The experiment suggests that even low levels of social pressure without face to face interaction on customers leads to a …

experiment randomly assigning participants to four raffle treatments to examine the effectiveness of alternative incentive … revenue gains are available on both margins. Our experiment, and others like it, illustrates the power of field experiments to …

To investigate the external validity of laboratory results, we combine a public good experiment with three treatments … in a field experiment. One treatment offers the opportunity to free-ride, the other two are placebo treatments. We …

the impacts of monetary gift exchange and of expressions of respect on salespersons' reciprocity when purchasing doner … salespersons exhibit positive reciprocity in response both to a monetary gift and to compliments regarding the product. The …

field experiment that compares the principal-first and agent-first orderings to each other and a gift-less control …

field experiment that compares the principal-first and agent-first orderings to each other and a gift-less control …