Collaborative Research: Equilibria in Health Exchanges: Adverse Selection, Reclassification Risk, and Dynamic Contracting

医疗保险市场受到效率和公平规定驱动的各种监管的约束。患者保护和平价医疗法案(PPACA)建议使用交易所；在交易所，保险公司提供年度保单的市场受几个定价规则的约束。尽管公众对健康交换进行了大量讨论，但对替代设计的可能结果和福利影响的正式分析很少。这个项目的目标是在一个受监管的市场中建立保险公司竞争的模型，以便从理论和经验上研究交易所的功能。PI在Rothschild和Stiglitz(1976)、Wilson(1977)、Miyazaki(1977)和Riley(1985)模型的基础上开发了一个保险交易所模型。他们建议研究交易所中均衡的性质，并提出一种算法，利用总体及其对健康风险和偏好的估计分布来寻找均衡。PI使用有关个人级别的健康计划选择和来自大公司的健康声明的详细信息来模拟交换。偏好从结构选择模型中恢复，而健康风险的分布则通过专业的风险评估软件程序进行量化。初步结果揭示了由于信息不对称/逆向选择而导致的许多解体。一种可能减少这种解体的方法是允许基于预先存在的条件进行定价，这是PPACA禁止的。然而，从长远来看，对预先存在的疾病进行定价可能会使消费者面临重新分类的风险。私人侦查员将审查这一规则的影响。初步结果表明，重新分类风险的损失可能远远超过逆向选择的损失。此外，在没有补贴的情况下，如果没有强制性的参与，大约20%的人口将选择退出交易所。投资促进局亦建议研究交易所多个可能的替代设计的影响。其中之一是目前的风险调整建议，这是HHS最近提出的。

Health insurance markets are subject to a variety of regulations driven by efficiency and equity provision. The Patient Protection and Affordable Care Act (PPACA) proposes the use of exchanges; markets where insurers offer yearly policies subject to several pricing rules. Despite the substantial public discussion of health exchanges, there has been little formal analysis of the likely outcomes and welfare impact of alternative designs. The goal of this project is model of insurer competition in a regulated marketplace in order to investigate both theoretically and empirically the functioning of exchanges.The PIs develop a model of an insurance exchange building on the models of Rothschild and Stiglitz (1976), Wilson (1977), Miyazaki (1977) and Riley (1985). They propose to investigate the properties of equilibria in exchanges and present an algorithm to find equilibria using a population and their estimated distributions of health risk and preferences. The PIs use detailed information on individual-level health plan choices and health claims from a large firm to simulate an exchange. Preferences are recovered from a structural choice model, while the distribution of health risk is quantified with a professional risk assessment software program.Preliminary results reveal lot of unraveling due to asymmetric information/adverse selection. One way to potentially reduce this unraveling is by allowing pricing based on pre-existing conditions, which the PPACA bans. However, in the longer run, pricing pre-existing conditions can subject consumers to re-classification risk. The PIs will examine the effects of this rule. Preliminary results suggest the losses from reclassification risk may far outweigh the adverse selection losses. In addition, absent subsidies, around 20% of the population would opt out of the exchange in the absence of a mandate compelling participation. The PIs also propose to examine the impact of a number of possible alternative designs of an exchange. One of these is the current suggestions for risk adjustment, which has recently been proposed by HHS.