This thesis studies the optimal provision of social insurance in the presence of asymmetric information. Agents are subject to idiosyncratic shocks and sign contracts to insure against them. The main friction present in all the environments studied in this thesis is that these shocks are privately observed by agents. Each chapter of the thesis considers a particular environment with asymmetric information and for each case we characterize the optimal contract and study its quantitative implications.;The focus of chapter 2 is to study the quantitative properties of constrained efficient allocations in an environment where risk sharing is limited by the presence of private information. We consider a life cycle version of a standard Mirrlees economy where shocks to labor oroductivity have a component that is public information and one that is private information. agents sign an exclusive contract with a planner that prescribes the consumption and output allocations. The presence of private shocks has important implications for the age profiles of consumption and income implied by the optimal contract. First, they introduce an endogenous dispersion of continuation utilities. As a result, consumption inequality rises with age even if the variance of the shocks does not. Second, they introduce an endogenous rise of the distortion on the marginal rate of substitution between consumption and leisure over the life cycle. This is because, as agents age, the ability to properly provide incentives for work must become less and less tied to promises of benefits (through either increased leisure or consumption) in future periods. Both of these features are also present in the US survey data. We look at the data through the lens of our model and estimate the fraction of labor productivity that is private information. We find that for the model and data to be consistent, a large fraction of shocks to labor productivity must be private information.;In chapter 3 we study how the presence of non-exclusive contracts limits the amount of insurance provided in a decentralized economy. We consider a dynamic Mirrleesian economy in which agents are privately informed about idiosyncratic labor productivity shocks. Agents sign privately observable insurance contracts with multiple firms (i.e., they are non-exclusive), which include both labor supply and savings aspects. Firms have no restriction on the contracts they can offer, interact strategically. In equilibrium, contrary to the case with exclusive contracts, a standard Euler equation holds, the marginal rate of substitution between consumption and leisure is equated to the worker's marginal productivity. Also, each agent receives zero net present value of transfers. To sustain this equilibrium, more than one firm must be active and must also offer latent contracts to deter deviations to more profitable contingent contracts. In this environment, the non-observability of contracts removes the possibility of additional insurance beyond self-insurance. To test the model, we allow firms to observe contracts at a cost. The model endogenously divides the population into agents that are not monitored and have access to non-exclusive contracts and agents that have access to exclusive contracts. We use US survey data and find that high school graduates satisfy the optimality conditions implied by the non-exclusive contracts while college graduates behave according to the second group.;Chapter 4 considers the Rothschild and Stiglitz (1976) insurance environment relaxing the assumption of exclusivity of insurance contracts. Agents are privately informed about the probability of their income realization, which is publicly observed. Agents can engage in multiple insurance contract simultaneously and the terms of these contracts are not observed by other firms. Insurance providers behave non-cooperatively and compete offering menus of insurance contracts from an unrestricted contract space. We derive conditions under which a separating equilibrium exists and fully characterize it. The equilibrium allocation consists of agents with a lower probability of accident purchasing no insurance and agents with higher accident probability buying the actuarially fair competitive level of insurance. The equilibrium allocation also constitutes a linear price schedule for insurance. To sustain this allocation firms must offer latent contracts. We show that latent menus can prevent cream-skimming strategies, however pooling equilibrium still fails to exists.
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机译：本文研究了信息不对称下社会保险的最优供给。代理商会遭受特殊的冲击，并签订合同以确保他们免受损害。本文研究的所有环境中存在的主要摩擦是，这些冲击是由代理人私下观察到的。论文的每一章都考虑了一个信息不对称的特殊环境，我们针对每种情况描述了最优合同的特征并研究了其量化含义。第二章的重点是研究在风险分担为零的环境下约束有效分配的量化性质。受私人信息的限制。我们考虑一个标准的Mirrlees经济的生命周期版本，其中对劳动力流动性的冲击有一个组成部分，即公共信息和私人信息。代理商与计划者签订排他性合同，规定消耗和产出分配。私人冲击的存在对最佳合同所隐含的消费和收入的年龄特征具有重要影响。首先，他们引入了连续性工具的内生性分散。结果，即使冲击的变化没有，消费不平等也会随着年龄的增长而增加。其次，它们在整个生命周期内导致了消费和休闲之间的边际替代率的扭曲的内生性上升。这是因为，随着代理商年龄的增长，在将来的时期内，正确提供工作激励的能力必须越来越少地与对收益的承诺（通过增加休闲或消费）联系在一起。美国调查数据中也都具有这两种功能。我们通过模型的角度查看数据，并估计劳动生产率中私人信息所占的比例。我们发现，为了使模型和数据保持一致，对劳动生产率的冲击必须很大一部分是私人信息。在第3章中，我们研究了非排他性合同的存在如何限制去中心化经济体中提供的保险数量。我们考虑一个动态的米尔里斯经济，在这种经济中，代理人被私下告知特有的劳动生产率冲击。代理商与多家公司签订私人可观察的保险合同（即非排他性合同），其中包括劳动力供应和储蓄方面。企业对他们可以提供的合同，战略互动没有任何限制。在均衡状态下，与排他性合同的情况相反，一个标准的欧拉方程成立，消费和休闲之间的边际替代率等于工人的边际生产率。同样，每个代理收到的转移净现值为零。为了维持这种平衡，不止一家公司必须活跃，还必须提供潜在合同以阻止对利润更高的或有合同的偏离。在这种环境下，合同的不可观察性消除了除了自我保险之外的其他保险的可能性。为了测试模型，我们允许公司以一定成本观察合同。该模型以内生的方式将总体划分为不受监控且可以访问非排他性合同的代理和可以访问排他性合同的代理。我们使用美国的调查数据，发现高中毕业生满足非排他性合同所隐含的最优条件，而大学毕业生则按照第二组表现。;第4章考虑了Rothschild and Stiglitz（1976）的保险环境放松了排他性假设保险合同。代理人被私下告知他们实现收入的可能性，这是公开观察到的。代理人可以同时参与多个保险合同，而其他公司未遵守这些合同的条款。保险提供者采取不合作的行为，并在不受限制的合同空间中竞争提供保险合同的菜单。我们得出存在分离均衡的条件并对其进行充分表征。均衡分配由事故概率较低的代理商购买保险而构成，事故概率较高的代理商购买精算公平竞争水平的保险。均衡分配还构成了保险的线性价格表。为了维持这种分配，公司必须提供潜在的合同。我们表明，潜在菜单可以防止脱脂策略，但是池平衡仍然不存在。
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