A study was proposed at Maven University to conduct a survey using a dietary questionnaire, a motion sickness history questionnaire, and a "disgust sensitivity" survey. To protect participants, and to preclude any bias, the researchers preferred that participation in the study be anonymous, even to them. To assure anonymity while paying compensation, a lottery for $500, with odds depending on number of entries, was proposed, together with a carefully developed scheme for preserving the anonymity of the winner.
Prior to this, the Maven IRB had argued that a lottery could not be used as compensation, first because it is gambling, and second because it is unfair that not all subjects are paid the same amount. However, they ultimately agreed that a lottery is an acceptable form of compensation. In response to this proposal, they ruled that the amount of the prize could not be advertised, because $500 is "coercive".
The researchers argued that a lottery is not gambling, because subjects do not risk their own money. They further argued that it is not unfair to pay subjects differently, because all have an equal opportunity to win the prize and know that beforehand.
Because of the voluntary and anonymous nature of participation, the research is minimal risk, and so the size of the prize should not matter. The researchers argued that the size of the prize is not as relevant as the expected value. With ten participants, the expected value of the prize would be only $50, which can hardly be viewed as coercive. The researchers further argued that the subjects, as Maven U. undergraduates, were adults who could legally participate in state operated lotteries. The students would be briefed that a lottery with a $500 prize is worth substantially less than $500 to the average participant.