Is it acceptable to pay nothing or little to challenge trial participants?

By Sandro Ambuehl, Axel Ockenfels and Alvin E Roth.

Concerns with (high) incentives feature prominently among ethicists. In the broad public and amongst economists, by contrast, there is much agreement that workers providing a service should be compensated fairly, and that work involving more discomfort and risk should be compensated more generously. This intuition extends to volunteers who engage in risky activities for private benefit (roofers, miners) and for the greater good (bomb squads, war correspondents, firefighters). Accordingly, labor regulations impose floors (minimum wage laws), not caps on compensation – especially with regards to vulnerable individuals such as the poor. Moreover, caps, even if intended to protect against undue inducement, raise concerns about illegal price-fixing that disadvantages workers.  Such limits on payment for egg donors have successfully been challenged in court.

In the case of controlled human infection model (CHIM) trials, insufficient compensation creates additional issues. It may impede the recruitment of enough suitable subjects, particularly from disadvantaged populations. Yet, delays in vaccine development not only prolong disruption of social, educational, and economic activity but also lead to excess infections and deaths. Unlike paid CHIM participants, individuals exposed to such infection do not accept it voluntarily, are not compensated for it, and are unlikely to receive the level of medical supervision afforded to closely monitored CHIM participants. The hurdle for capping payments in an otherwise carefully constructed and monitored CHIM trial is thus very high, and any such intervention should be scrutinized based on our best knowledge about how payments actually affect prospective participants and the quality of their decision making.

Indeed, we hope that the debates about payments in medical research, and on other transactions subject to restrictions on payments such as blood plasma donations, will converge as empirical results accumulate. To date, there is empirical evidence on the underlying motivations for volunteering, on the impact of high payment on human risk taking, on decision quality and well-being, on the signal value of small payments, on strategies to evade regulation, and on the general public’s assessment of appropriate activities and  payments. Moreover, there are studies that document biases affecting normative judgment in general, and biases affecting paternalistic restrictions and moral intuitions in particular.

Awareness of pertinent empirical research and of biases affecting normative decision making is crucial for sound ethical judgment. It appears to have contributed to the increasing recognition that underpayment is no less ethically problematic than overpayment.


Paper title: Payment in Challenge Studies from an Economics Perspective

Authors: Sandro Ambuehl, Axel Ockenfels and Alvin E Roth


SA: Department of Economics, University of Zurich, Zurich, Switzerland.

AO: Department of Economics, Center for Social and Economic Behavior, University of Cologne, Cologne, Germany.

AER: Department of Economics, Stanford University, Stanford, United States.

Competing interests: The authors declare no competing interests.

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