Behavioral Hazard in Health Insurance*
研究发现，除了传统的道德风险，人们还会因认知错误（行为风险）而滥用或忽视医疗，仅靠需求曲线评估福利会严重偏差；本文推导了同时考虑道德与行为风险的最优共付公式，为价值导向保险设计和行为助推提供理论基础。
Abstract A fundamental implication of standard moral hazard models is overuse of low-value medical care because copays are lower than costs. In these models, the demand curve alone can be used to make welfare statements, a fact relied on by much empirical work. There is ample evidence, though, that people misuse care for a different reason: mistakes, or “behavioral hazard.” Much high-value care is underused even when patient costs are low, and some useless care is bought even when patients face the full cost. In the presence of behavioral hazard, welfare calculations using only the demand curve can be off by orders of magnitude or even be the wrong sign. We derive optimal copay formulas that incorporate both moral and behavioral hazard, providing a theoretical foundation for value-based insurance design and a way to interpret behavioral “nudges.” Once behavioral hazard is taken into account, health insurance can do more than just provide financial protection—it can also improve health care efficiency.