This paper structurally estimates a demand and supply model of Medicare Part D and evaluates counterfactual scenarios that introduce a public option competing alongside private insurers. The results show that a public option with a cost advantage expands coverage and crowds out private insurer enrollment, but has little effect on market premiums. Additional subsidy payments covering the expanded base of enrollees offset welfare gains regardless of the public option's cost position. In scenarios where private insurers cream skim the public option, risk adjustment payments create a pricing wedge that acts as a de facto subsidy for private insurers and a tax on the public option, limiting the public option's penetration but improving welfare through lower private insurer premiums. Risk corridors can be used as a lever to regulate the pricing wedge and redistribute surplus.

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公共健康保险方案的后果：Medicare D部分的证据

本文从结构上估计了Medicare D部分的供需模型，并评估了反事实情景，该情景引入了与私人保险公司竞争的公共期权。结果表明，具有成本优势的公共期权可以扩大保险范围，排挤私人保险公司的参保人数，但对市场溢价影响很小。不论公共选择权的成本状况如何，覆盖入学人数扩大的额外补贴付款都会抵消福利收益。在私人保险公司略过公共期权的情况下，风险调整付款会产生定价楔，这实际上是对私人保险公司的补贴和对公共期权的征税，限制了公共期权的渗透率，但通过降低私人保险公司的保费来提高福利。