Health Insurance without Single Crossing: Why Healthy People have High Coverage
标准保险模型预测高风险人群有高覆盖率，但实证显示高收入人群风险更低却保险更多。本文证明收入差异导致单交条件失效，并分析市场结构解释这一现象。
Standard insurance models predict that people with high risks have high insurance coverage. It is empirically documented that people with high income have lower health risks and are better insured. We show that income differences between risk types lead to a violation of single crossing in an insurance model where people choose treatment intensity. We analyse different market structures and show the following: If insurers have market power, the violation of single crossing caused by income differences and endogenous treatment choice can explain the empirically observed outcome. Our results do not rely on differences in risk aversion between types.