中文摘要
我们分析了一个竞争性医疗保险市场中最优风险调整的模型,该市场同时存在事前逆向选择和事后道德风险。我们的第一个发现是:与仅有逆向选择的市场不同,在道德风险同样重要的环境中,要消除保险人的选择激励,所需的风险调整支付并不需要在各类消费者之间完全均等化成本。因此,当前试图校正消费者之间所有可预测成本差异的做法是错误的。其次,如果风险调整体系的出资方不仅关注消除选择扭曲,还希望向高风险消费者进行再分配,那么由此所需的更高风险调整支付将在高风险消费者的合同中引入选择扭曲。这导致对遭受严重健康冲击的人群在均衡中提供了过多的医疗服务。最后,保险人的市场势力会产生抵消性激励,这有助于风险调整者对抗选择扭曲,但与同样关注再分配的风险调整规制相悖。
Abstract
We analyse a model of optimal risk adjustment in competitive health-insurance markets which suffer from both ex-ante adverse selection and ex-post moral hazard. We find, firstly, that, unlike in an adverse-selection-only market, in an environment where also moral hazard is important, removing insurers' selection incentives requires risk-adjustment payments that do not fully equalize costs among consumer types. Current practice of attempting to correct for all predictable cost differences among consumers is then misguided. Secondly, if the sponsor of the risk-adjustment system is not only concerned with eliminating selection distortions, but also wants to redistribute towards high-risk consumers, the required higher risk-adjustment payments will introduce selection distortions in high-risk consumers' contracts. This leads to excessive equilibrium provision of care for those suffering severe health shocks. Finally, insurer market power creates countervailing incentives, helping the risk adjuster to combat selection distortions but working against a risk-adjustment regulation that also cares about redistribution.