Intertemporal equilibria with Knightian uncertainty

We study a dynamic and infinite-dimensional model with incomplete multiple prior preferences. In interior efficient allocations, agents share a common risk-adjusted prior and subjective interest rate. Interior efficient allocations and equilibria coincide with those of economies with subjective expected utility and priors from the agents? multiple prior sets. A specific model with neither risk nor uncertainty at the aggregate level is considered. Risk is always fully insured. For small levels of ambiguity, there exists an equilibrium with inertia where agents also insure fully against Knightian uncertainty. When the level of ambiguity exceeds a critical threshold, full insurance no longer prevails and there exist equilibria with inertia where agents do not insure against uncertainty at all. We also show that equilibria with inertia are indeterminate.     

Voluntary Contributions to a Mutual Insurance Pool

We study mutual‐aid games in which individuals choose to contribute to an informal mutual insurance pool. Individual coverage is determined by the aggregate level of contributions and a sharing rule. We analyze theoretically and experimentally the (ex ante) efficiency of equal and contribution‐based coverage. The equal coverage mechanism leads to a unique no‐insurance equilibrium while contribution‐based coverage develops multiple equilibria and improves efficiency. Experimentally, the latter treatment reduces the amount of transfers from high contributors to low contributors and generates a “dual interior equilibrium.” That dual equilibrium is consistent with the co‐existence of different prior norms which correspond to notable equilibria derived in the theory. This results in asymmetric outcomes with a majority of high contributors less than fully reimbursing the global losses and a significant minority of low contributors less than fully defecting. Such behavioral heterogeneity may be attributed to risk attitudes (risk tolerance vs risk aversion) which is natural in a risky context.     

Corporate insurance with optimal financial contracting

Summary. This paper attemps to rationalize the use of insurance covenants in financial contracts, and shows how external financing generates a demand for insurance by risk-neutral entrepreneurs. In our model, the entrepreneur needs external financing for a risky project that can be affected by an accident during its realization. Accident losses and final returns are private information to the firm, but they can be evaluated by two costly auditing technologies. We derive the optimal financial contract: it is a bundle of a standard debt contract and an insurance contract with franchise, trading off bankruptcy costs vs auditing costs. We then analyze how this optimal contract can be achieved by decentralized trading on competitive markets when insurance and credit activities are exogenously separated. With additive risks, the insurance contract involves full coverage above a straight deductible. We interpret this result by showing how our results imply induced risk aversion for risk-neutral firms. Received: December 14, 1998; revised version: August 11, 1999     

Racial disparities in life insurance coverage

We evaluate the extent to which there are racial disparities in life insurance coverage using multiple years of the Survey of Income and Program Participation between 2001 and 2010. We find that African Americans hold significantly more life insurance – especially whole life insurance – after controlling for other factors. We demonstrate that our findings diverge from prior work because we examine all households instead of focusing exclusively on married and cohabitating households. Although earning shocks due to mortality likely contribute to racial disparities in wealth, the influence is mitigated by the racial composition of life insurance holdings.     

Adverse Selection and the Decline in Private Health Insurance Coverage in Australia: 1989–95

The decline in private health insurance coverage over the period 1989–95 is analysed using the ABS National Health Surveys. Individuals' health status and health risk behaviours are found to be significant determinants of their decision to purchase private health insurance. At a point in time, the pool of the insured is very heterogeneous, with a mix of both good and bad health risks. It is found that the decline in insurance coverage over the period 1989–95 coincided with an increase in the degree of 'adverse selection' within the insured population.     

Genetic Information: Comparing Alternative Regulatory Approaches When Prevention Matters

We compare the alternative approaches used for regulating genetic information in the health insurance market when prevention measures are available. In the model, firms offer insurance contracts to consumers who are initially uninformed of their risk type but can obtain such information by performing a costless genetic test. A crucial ingredient of our analysis is that information has decision‐making value since it allows for the optimal choice of a self‐insurance action (secondary prevention). We focus on the welfare properties of market equilibria obtained under the different regulatory schemes and, by using an intuitive graphical analysis, we rank them unambiguously. Our results show that Disclosure Duty weakly dominates the other regulatory schemes and that Strict Prohibition represents the worst regulatory approach.     

Nonlinear incentive provision in Walrasian markets: a Cournot convergence approach

The paper studies insurance with moral hazard in a system of contingent-claims markets. Insurance buyers are modelled as Cournot monopolists or oligopolists. The other agents condition their expectations on market prices, as in models of rational-expectations equilibrium with asymmetric information. Thereby they correctly anticipate accident probabilities corresponding to effort incentives induced by insurance buyers’ net trades. When there are many agents to share the insurance buyers’ risks, Cournot equilibrium outcomes are close to being second-best. In contrast, if insurance buyers are price takers, equilibria fail to exist or are bounded away from being second-best.     

Public provision of health insurance and aggregate saving in an overlapping generations model with endogenous health risk: The South Korean case

This paper examines the effect of expanding public health insurance in South Korea on medical expenditures and aggregate saving using an overlapping generations model with endogenous health risk. South Korea had a substantial underinsured population, which is aging rapidly. Higher public health insurance benefits reduce individual medical expenditure and health risks but lead to a modest decline in individual and aggregate saving. Even after the expansion, the medical care coverage remains incomplete, and the elderly face a substantial risk of out-of-pocket medical expenditures.     

Wealth inequality and dynamic stability

We explore the link between wealth inequality and stability in a two-sector neoclassical growth model with heterogeneous agents. We show that when the inverse of absolute risk aversion (or risk tolerance) is a strictly convex function, wealth inequality is a factor that favors instability. In the opposite case, inequality favors stability. Our characterization also shows that whenever absolute risk tolerance is linear, as when preferences exhibit hyperbolic absolute risk aversion (HARA), wealth heterogeneity is neutral.     

Insurance of Household Risks and the Rebalancing of the Chinese Economy: Health Insurance,Health Expenses and Household Savings

This paper studies the effects of a public insurance system, the New Cooperative Medical Scheme (NCMS) on household savings in rural China. We develop a theoretical model in which we explain the impact of health insurance on savings through the impact of health insurance on out‐of‐pocket (OOP) health expense given the household level of wealth and seriousness of illness. We test the model empirically using data from the China Health and Nutrition Survey. We run endogenous and exogenous quantile regressions to evaluate the effects of NCMS participation on the distributions of household savings and OOP health expense. The impact of NCMS varies with the seriousness of illness. The NCMS induces an increase in OOP health expense for mild illness and, inversely, a decrease in health payments for more serious illnesses. The NCMS also leads to a higher incidence of catastrophic healthcare spending. The impact of the NCMS, given a certain state of illness, also varies with the household level of wealth. Poor households face health expense for both mild and serious illnesses. As the NCMS has opposite effects on the OOP expense for these two kinds of illness, we observe no effect on poor households’ precautionary savings. Because the decrease in OOP health expense for mild illness is larger for less poor households, the NCMS induces a decrease in their savings. For the most affluent households, the higher decrease in OOP spending on most moderate illness is dominated by a sharp increase in catastrophic expense, causing an increase in savings. To significantly reduce household savings and enhance household consumption, the NCMS has to offer better coverage against both serious and catastrophic health risks.     

Anti-insurance: Analysing the Health Insurance System in Australia

This paper develops a model to analyse the Australian health insurance system when individuals differ in their health risk and this risk is private information. In Australia private insurance both duplicates and supplements public insurance. We show that, absent any other interventions, this results in implicit transfers of wealth from those most at risk of adverse health to those least at risk. At the social level, these transfers represent a mean preserving spread of income, creating social risk and lowering welfare – what we call anti-insurance. The recently introduced rebate on private health insurance can improve welfare by alleviating anti-insurance.     

The Economics of Ageing—What do you Face?

The economics of ageing is the study of economic decision‐making by individuals and government aimed at fostering well‐being in old age. These decisions include preparing for old age and dealing with the risks of old age. The risks are substantial. Using the life‐cycle model, this article considers the risks for well‐being that people face in retirement and the role of government and private insurance in meeting those risks. The perspective of the life‐cycle model is also used to consider the gender gap in wealth on retirement.     

IDIOSYNCRATIC AND AGGREGATE RISKS,INEQUALITY AND GROWTH

The paper disaggregates productivity shocks at a firm level into idiosyncratic and aggregate risks, and studies their impacts on inequality, growth and welfare. It develops a growth model with human capital and incomplete insurance and credit markets that provides a closed‐form solution for income inequality dynamics. We find that uninsured idiosyncratic risks are the most important determinants of inequality, growth and welfare. They are the source of nondegenerate wealth distribution. A lower weight of these shocks leads to lower steady‐state inequality, higher growth and welfare. A redistribution of income that serves as social insurance against such risks increases welfare and decreases inequality. But, it also decreases growth by distorting individual consumption and saving decisions.     

Why is the market for long-term care insurance so small?

Long-term care represents one of the largest uninsured financial risks facing the elderly in the United States. We present evidence of supply side market failures in the private long-term care insurance market. In particular, the typical policy purchased exhibits premiums marked up substantially above expected benefits. It also provides very limited coverage relative to the total expenditure risk. However, we present additional evidence suggesting that the existence of supply side market failures is unlikely, by itself, to be sufficient to explain the very small size of the private long-term care insurance market. In particular, we find enormous gender differences in pricing that do not translate into differences in coverage, and we show that more comprehensive policies are widely available, if seldom purchased, at similar loads to purchased policies. This suggests that factors limiting demand for insurance are also likely to be important in this market. Our evidence also sheds light on the likely nature of these demand-side factors.     

基于D-D模型的退保风险传染效应研究

The prevention and control of financial risk has been placed at a more prominent position at present. Preventing the risk of cross infection and systemic risk is one of the most important tasks of the current insurance industry. The crisis signal of an insurance company may shake the confidence of consumers to a large extent, leading to a “flock effect” that causes the risk spillovers and make the insured surrender or no longer renew, which could eventually lead to systemic risk. In this paper, based on a micro perspective and D-D model, we take the insurance companies different levels of loss claims as a key variable to establish a closed insurance market model, to study the relationship between the surrender behavior and the risk contagion, and carries on the numerical simulation and the sensitivity analysis to the risk infectivity caused by the insured under different crises. The study found that there is a critical jump point when the insured faces a different degree of crisis in the insurance company, and the behavior of the insured has a certain degree of influence on the systemic risk transmission. The regulatory authorities and insurance companies need to pay attention to the contagion effects of systemic risk caused by expectations and behaviors of policyholders.     

Market evidence of misperceived mortality risk

We construct and implement a test of rational consumer behavior in a high-stakes financial market. In particular, we test whether consumers make systematic mistakes in perceiving their mortality risks. We implement this test using data from secondary life insurance markets where consumers with a life-threatening illness sell their life insurance policies to firms in return for an up-front payment. We compare predictions from two models: one with consumers who correctly perceive their mortality risk, and one with consumers who are misguided about their life expectancy, and find that our data are most consistent with the predictions made by the second model.     

THE WEALTH EFFECTS OF INCOME INSURANCE

Precautionary savings models suggest that wealth should rise with income risk. Risk is reduced by means-tested transfers, however, which implies that transfer programs should discourage private wealth accumulation. We offer a comprehensive empirical assessment based on variation across states in the generosity of a number of programs, specifically unemployment insurance and means-tested transfers (Aid to Families with Dependent Children and Food Stamps). We use monthly data on married couples from the Survey of Income and Program Participation (SIPP) to regress wealth on income, income risk, and various measures of transfer generosity. The results support the precaution-ary savings model and reveal moderate negative wealth effects of both unemployment insurance and means-tested transfers, with an elasticity of about −0.18.     

The Effects of Competition on Banks’ Risk Taking

We consider the joint effect of competition and deposit insurance on risk taking by banks when bank risk is unobservable to depositors. It turns out that the magnitude of risk taking depends on the structure and side of the market in which competition takes place. If the bank is a monopoly or banks are competing only in the loan market, deposit insurance has no effect on risk taking. Banks in this situation tend to take risk, although extreme risk taking is avoided. In contrast, introducing deposit insurance increases risk taking if banks are competing for deposits. Then, deposit rates become excessively high, thereby forcing banks to take extreme risks.     

Leaving the market or reducing the coverage? A model-based experimental analysis of the demand for insurance

This study develops a theoretical, and experimental analysis addressing the issue of premium variations on the demand for insurance. Accounting for risk attitudes, our contribution disentangles the decision to buy insurance from the conditional demand (the non-null demand for insurance). Partially validating our theoretical predictions, our experimental results show that, when it has an effect, a non-massive increase in the premium (either in the unit price or the fixed cost) exclusively results in an exit from the insurance market (the risk lovers first, then the risk averters). Moreover, our study highlights a key feature of risk-seeking agents' behavior; they exhibit behavior consistent with gambling and opportunism rather than a lack of interest in insurance.     

When is market incompleteness irrelevant for the price of aggregate risk (and when is it not)?

In a standard incomplete markets model with a continuum of households that have constant relative risk aversion (CRRA) preferences, the absence of insurance markets for idiosyncratic labor income risk has no effect on the premium for aggregate risk if the distribution of idiosyncratic risk is independent of aggregate shocks and aggregate consumption growth is independent over time. In equilibrium, households only use the stock market to smooth consumption; the bond market is inoperative. Furthermore, the cross-sectional distributions of wealth and consumption are not affected by aggregate shocks. These results hold regardless of the persistence of idiosyncratic shocks, even when households face tight solvency constraints. A weaker irrelevance result survives when we allow for predictability in aggregate consumption growth.