Incentivizing Participation in Clinical Trials

The difficulty of recruiting patients is a well-known issue in clinical trials which inhibits or sometimes precludes them in practice. We interpret this issue as a non-standard version of exploration-exploitation tradeoff: here, the clinical trial would like to explore as uniformly as possible, whereas each patient prefers ``exploitation", i.e. treatments that seem best. We study how to incentivize participation by leveraging information asymmetry between the trial and the patients. We measure statistical performance via worst-case estimation error under adversarially generated outcomes, a standard objective for clinical trials. We obtain a near-optimal solution in terms of this objective. Namely, we provide an incentive-compatible mechanism with a particular guarantee, and a nearly matching impossibility result for any incentive-compatible mechanism. Our results extend to agents with heterogeneous public and private types.