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

健康保险市场受各种效率和公平规定的约束。《患者保护和平价医疗法案》（PPACA）建议使用交换机制；保险公司根据几种定价规则提供年度保单的市场。尽管公众对健康交换进行了大量讨论，但对替代方案的可能结果和福利影响的正式分析却很少。该项目的目标是在受监管的市场中建立保险公司竞争模型，以便从理论上和经验上调查交易所的功能。pi在Rothschild和Stiglitz（1976）、Wilson（1977）、Miyazaki（1977）和Riley（1985）的模型基础上发展了一个保险交易所的模型。他们建议研究交换中均衡的性质，并提出一种算法，利用人口及其健康风险和偏好的估计分布来找到均衡。pi使用个人层面的健康计划选择和大型公司的健康声明的详细信息来模拟交换。从结构选择模型中恢复偏好，同时使用专业风险评估软件程序对健康风险的分布进行量化。初步研究结果显示，由于信息不对称/逆向选择，大量的解开。一种可能减少这种解体的方法是允许基于已有条件的定价，这是PPACA禁止的。然而，从长远来看，对既存状况进行定价可能会使消费者面临重新分类的风险。pi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，如果没有补贴，大约20%的人会在没有强制参与的情况下选择退出保险交易所。pi还建议研究一些可能的交易所替代设计的影响。其中之一是目前的风险调整建议，这是最近由卫生与公众服务部提出的。

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.