Incentives in Experiments: A Theoretical Analysis

Experimental economists currently lack a convention for how to pay subjects in experiments with multiple tasks. We provide a theoretical framework for analyzing this question. Assuming statewise monotonicity and nothing else, we prove that paying for one randomly chosen problem-the random problem selection mechanism-is essentially the only incentive compatible mechanism. Paying for every period is similarly justified when we assume only a no complementarities at the top condition. To help experimenters decide which is appropriate for their particular experiment, we discuss empirical tests of these two assumptions.