The Affordable Care Act (ACA) provided funding to help states expand Medicaid eligibility to those earning up to 138% of the Federal Poverty Level. Such expansions in Medicaid eligibility, however, could “crowd out” private insurance coverage, including changes in coverage relating to other ACA provisions. To estimate the extent of such crowd out, I use a difference-in-differences empirical approach, examining changes in health insurance coverage sources among low-income Americans in states that expanded eligibility relative to comparable individuals in states that did not. Using American Community Survey data from 2009 to 2019, I find a 43% crowd-out rate, consisting of a 10.7 percentage point relative increase in Medicaid coverage among low-income adults and a 4.6 percentage point relative decline in private health insurance among respondents in states that expanded Medicaid eligibility. Among working adults, my estimates imply a larger 56% rate of crowding out. Event study analyses provide support for a causal interpretation for my findings. I further show that my estimates are robust to different sample restrictions and estimation choices, are not subject to the issues raised by the new difference-in-differences literature, and are similar when I use approaches to identifying crowd out common in the existing literature.

中文翻译：

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《平价医疗法案》的医疗补助资格扩展是否排挤了私人医疗保险覆盖范围？


《平价医疗法案》(ACA) 提供资金帮助各州将医疗补助资格扩大到那些收入达到联邦贫困线 138% 的人。然而，医疗补助资格的这种扩大可能会“挤出”私人保险承保范围，包括与其他平价医疗法案条款相关的承保范围变化。为了估计这种挤出的程度，我使用了双重差异实证方法，研究了那些扩大了资格的州的低收入美国人相对于没有扩大资格的州的可比个人的医疗保险覆盖来源的变化。使用 2009 年至 2019 年的美国社区调查数据，我发现 43% 的挤出率，其中低收入成年人的医疗补助覆盖率相对增加了 10.7 个百分点，而受访者的私人健康保险相对下降了 4.6 个百分点。声明扩大了医疗补助资格。我的估计表明，在工作的成年人中，排挤率高达 56%。事件研究分析为我的发现的因果解释提供了支持。我进一步表明，我的估计对于不同的样本限制和估计选择是稳健的，不受新的双重差异文献提出的问题的影响，并且当我使用现有文献中常见的挤出方法时，我的估计是相似的。