Health insurance reform: The impact of a Medicare buy-in

The steady-state general equilibrium and welfare consequences of a Medicare buy-in program, optional for those aged 55–64, is evaluated in a calibrated life-cycle economy with incomplete markets. Incomplete markets and adverse selection create a potential welfare improving role for health insurance reform. We find that adverse selection eliminates any market for a Medicare buy-in if it is offered as an unsubsidized option to individual private health insurance. The subsidy needed to bring the number of uninsured to less than 5 percent of the target population could be financed by an increase in the labor income tax rate of just 0.03–0.18 percent depending on how the program is implemented.     

Information,market power,and price volatility

We consider demand function competition with a finite number of agents and private information. We show that any degree of market power can arise in the unique equilibrium under an information structure that is arbitrarily close to complete information. Regardless of the number of agents and the correlation of payoff shocks, market power may be arbitrarily close to zero (the competitive outcome) or arbitrarily large (so there is no trade). By contrast, price volatility is always lower than the variance of the aggregate shock across all information structures. Alternative trading mechanisms lead to very distinct bounds as a comparison with Cournot competition establishes.     

The substitutes condition and the lattice structure of the set of stable allocations

In the many-to-one matching model with contracts, I show that there is no restriction on preferences weaker than substitutable preferences which guarantees that the set of stable allocations is a lattice. Thus, when contracts are not substitutes, removing agents from the economy may decrease the payoffs to existing agents on both sides of the market.     

Welfare costs of reclassification risk in the health insurance market

We assess the quantitative importance of reclassification risk in the US health insurance market. Reclassification risk arises because the health conditions of individuals evolve over time, while a typical health insurance contract only lasts for one year. Thus, a change in the health status can lead to a significant change in the health insurance premium. We measure welfare gains from introducing explicit insurance against this risk in the form of guaranteed renewable health insurance contracts. We find that in the current institutional environment individuals are well-sheltered against reclassification risk and they only moderately gain from having access to these contracts. More specifically, we show that employer-sponsored health insurance and public means-tested transfers play an important role in providing implicit insurance against reclassification risk. If these institutions are removed, the average welfare gains from having access to guaranteed renewable contracts exceed 4% of the annual consumption.     

Does risk sharing increase with risk aversion and risk when commitment is limited?

I consider a risk-sharing game with limited commitment, and study how the discount factor above which perfect risk sharing is self-enforcing in the long run depends on agents׳ risk aversion and the riskiness of their endowment. When agents face no aggregate risk, a mean-preserving spread may destroy the sustainability of perfect risk sharing if each agent׳s endowment may take more than three values. With aggregate risk the same can happen with only two possible endowment realizations. With respect to risk aversion the intuitive comparative statics result holds without aggregate risk, but it holds only under strong assumptions in the presence of aggregate risk. In simple settings with two endowment values I also show that the threshold discount factor co-moves with popular measures of risk sharing.     

Financial markets with volatility uncertainty

We investigate financial markets under model risk caused by uncertain volatilities. To this end, we consider a financial market that features volatility uncertainty. We use the notion of G-expectation and its corresponding G-Brownian motion recently introduced by Peng (2007) to ensure a mathematically consistent framework. Our financial market consists of a riskless asset and a risky stock with price process modeled by geometric G-Brownian motion. We adapt the notion of arbitrage to this more complex situation, and consider stock price dynamics which exclude arbitrage opportunities. Volatility uncertainty results in an incomplete market. We establish the interval of no-arbitrage prices for general European contingent claims, and deduce explicit results in the Markovian case.     

Can Agents Be Better Off with Pay Caps?

A popular way to discipline the managers of companies or banks that got into trouble during the recent financial crisis has been to impose caps on managers' pay. Using a small extension of the standard principal–agent model, we argue that pay caps might serve the opposite purpose, because the agent might be better off with a pay cap. Specifically, we show that, given a fixed effort level to be implemented, the agent's expected utility can be decreasing in an upper bound for the agent's reward. The effect of pay caps on the general structure of optimal incentive contracts is also characterized. While an improvement of contracting information always helps the principal, it might increase or decrease the marginal cost of imposing pay caps.     

Optimal Social Insurance with Endogenous Health*

In this paper, I analyze optimal insurance against unemployment and disability in a private information economy with endogenous health and search effort. Individuals can reduce the probability of becoming disabled by exerting prevention effort. I show that the optimal sequence of consumption is increasing for a working individual and constant for a disabled individual. During unemployment, decreasing benefits are not necessarily optimal. The prevention constraint implies increasing benefits while the search constraint demands decreasing benefits while being unemployed. However, if individuals respond sufficiently to search incentives, the latter effect dominates the former and the optimal consumption sequence is decreasing during unemployment.     

The determinants of employers’ use of temporary contracts in the frictional labor market

This paper focuses on the following two primary reasons that employers use temporary contracts: to flexibly adjust employment and to screen workers. A search-matching framework is used to not only address employers’ endogenous choices in using temporary contracts, but also numerically identify the situations in which these contracts are likely to be used as a screening tool for permanent positions. This numerical exercise demonstrates that reducing employment protections in permanent jobs, reducing benefits for unemployed workers and raising the conversion probability from temporary to permanent employment will increase the relative proportion of employers who use temporary contracts as a screening device.