Experimental Design Details
In the online experiment the participants decide whether to allow the experimenter to offer a third person monetary compensation of varying amounts for registering as a bone marrow donor. The experiment consists of five parts and a post-experimental questionnaire, and follows a 2x2x2 factorial design. The first factor varies between subjects and alters whether the participants i) reveal their willingness-to-pay for the offer being made or not, or ii) make a discrete decision whether to approve the offer or not by choosing between the options “Approve,” “Do not approve,” and “Undecided: Let chance decide.” The second factor varies within subjects and alters whether the participant makes her decision for a low/regular monetary amount (in treatment “LOW”) or a very high monetary amount (in treatment “HIGH”). The order of these two treatments is randomly varied in Part 1 and Part 2 of the experiment. Part 3 repeats HIGH but i) in the treatment condition (“TREATMENT”) the participants are informed that, even if they approve the offer, the offer is made only if the person would be willing to accept the offer for the low monetary amount and ii) in the low probability condition (“LOW_PROB”) the participants are informed that, even if they approve the offer, with a certain probability the offer is not made. Whether a participant participates in TREATMENT or LOW_PROB varies between subjects. Part 4 (“UG”) elicits the behindness aversion of all participants using responder decisions in an ultimatum game. In Part 5 (“BELIEFS”) participants’ beliefs about reservation prices are assessed. Participants are asked to state their beliefs about the fraction of people who are willing to register as a bone marrow donor for various monetary amounts of compensation. Finally, a post-experimental questionnaire (“QUEST”) asks participants whether they consider the offer in HIGH to be coercive, and elicits risk-preferences, a psychological measure of envy, and basic demographics.
Additional treatments (see "Pre-Analyis Plan (Main Study Part 2)" for details):
I conduct six additional treatments. I conduct four additional treatments to further explore the result that individuals are much more favorable of the high payment offer in treatment Reservation Price (above referred to as "TREATMENT"). The treatments fully replicate the already conducted treatments Reservation Price and Probability (above referred to as “LOW_PROB”) but differ in the third choices participants make (unless for Reservation Price Replication, with which I exactly replicate the original treatment Reservation Price). As for the initial treatments, one decision and one participant will randomly be determined and her choice will be implemented. First, I replicate the main treatment, treatment Reservation Price, with treatment Reservation Price Replication. Second, I test the degree to which participants are permitting the €500 offer to potential donors with a reservation price of €10 or lower, because willing to sign up for €10 signals being a prosocial or altruistic person in treatment Social. The instructions equal the instructions of treatment Reservation Price except that, in the third part of the experiment, participants make a decision for a potential payment of €500, but they know that even if they permit the offer, the offer will only be made if the potential donor independently agrees to donate from €100 she receives, at least €50 to the German Red Cross. Third, I test a potential policy tool to use high economic incentives to incentivize stem cell donors: In the third part of treatment Lottery, participants decide whether to approve an offer that pays €500 with a probability of 50% and with 50% probability pays only €10. Fourth, I conduct a treatment in which the participants are offered the expected value of the lottery, that is, €255 (treatment Medium).
Finally, I conduct two treatments for the finding that the share of ethicists seems to be higher in the ethics committees than in the general public. In treatment Hyp Rep, the participants from the representative sample decide to approve an offer concerning monetary compensation for becoming a stem cell and bone marrow donor. They decide for a €10-compensation in Low and a €500-compensation in High. Participants make simple discrete decisions as to whether to approve the offers or not. Choices are not incentivized. Treatment Hyp Rep IRB resembles treatment Hyp Rep with the only difference that the participants are asked to make their decision as if they were a member of an IRB. The instructions also make clear that the participants should make the decision in the way they would make the decision if they were a member of an IRB and not how they think members of an IRB would decide.
Detailled explanations of all treatments can be found in the pre-analysis plan "Pre-Analyis Plan (Main Study Part 2)."