The Effect of Financial Compensation on Willingness to Supply a Child's Blood Sample: A Randomized Controlled Trial.

Medical researchers frequently need to collect blood samples from study participants. The determination of whether and how much compensation to provide to the participants is challenging. Institutional review boards typically allow researchers to provide a compensation that reimburses participants for their time and effort but is not so large as to be coercive. Using a randomized controlled trial, we estimate parents' responsiveness to financial compensation in terms of their willingness to provide their child's blood sample. We find that an additional dollar of compensation raises the willingness to provide a child's blood sample by about 0.5 percentage point at a base of 65%. This corresponds to an elasticity of .33. Using the findings, we provide general guidance on how compensation can be structured to strike a balance between appropriate compensation for participation and coercion.