THE WELFARE IMPACT OF REDUCING CHOICE IN MEDICARE PART D: A COMPARISON OF TWO REGULATION STRATEGIES*
通过估计医疗保险D部分市场的均衡模型，研究两种减少计划选择数量的策略对福利的影响，发现消除差异化维度（如取消“甜甜圈洞”覆盖）比限制企业数量造成的福利损失更小。
Motivated by widely publicized concerns that there are “too many” plans, we structurally estimate (and validate) an equilibrium model of the Medicare Part D market to study the welfare impacts of two feasible, similar‐sized approaches for reducing choice. One reduces the maximum number of firm offerings regionally; the other removes plans providing donut hole coverage—consumers’ most valued dimension. We find welfare losses are far smaller when coupled with elimination of a dimension of differentiation. We illustrate our findings’ relevance under current health care reforms, and consider the merits of instead imposing ex ante competition for entry.