Selective Trials: A Principal-Agent Approach to Randomized Controlled Experiments
研究了当实验结果受被试未观测努力影响时，如何设计随机对照实验。提出选择性试验可分离处理、努力及其交互效应，提升外部有效性，帮助识别错误信念和不恰当努力对处理效应的影响。
We study the design of randomized controlled experiments when outcomes are significantly affected by experimental subjects' unobserved effort expenditure. While standard randomized controlled trials (RCTs) are internally consistent, the unobservability of effort compromises external validity. We approach trial design as a principal-agent problem and show that natural extensions of RCTs—which we call selective trials—can help improve external validity. In particular, selective trials can disentangle the effects of treatment, effort, and the interaction of treatment and effort. Moreover, they can help identify when treatment effects are affected by erroneous beliefs and inappropriate effort expenditure.