农业保险制度对土地利用效应的经济学分析

本文通过建立农业生产局部均衡模型研究发现,农业保险制度的建立明显导致了粗放边际扩张,完全分开均衡精算公平农业保险制度不会对土地使用或其他任何生产决定造成影响.但是,在较现实的混同均衡精算公平农业保险制度下,农户将会把无农业保险时闲置的、边际质量更低劣的土地投入生产,而且农业保险补贴会进一步刺激农业生产在劣质土地上的粗放边际扩张并可能导致环境退化的问题.这对研究我国农业保险制度选择及其补贴政策对环境的影响具有一定的参考价值.     

Competitive Insurance Markets with Two Unobservables

I study a screening game in a competitive insurance market in which insurance customers differ with respect to both accident probability and degree of risk aversion. It is shown that indifference curves of customers may cross twice; thus the single crossing property does not hold. When differences in risk aversion are sufficiently large, firms cannot use policy deductibles to screen high-risk customers. Types may be pooled in equilibrium or are separated by raising premiums above actuarially fair levels. This leads to excessive entry of firms in equilibrium.     

The age-dependent value of time: a life cycle analysis

A life cycle framework is developed to examine how the value of time (VOT) changes as one ages. We consider two risk-sharing schemes, the Tonti scheme under which wealth is actuarially insured, and the Robinson Crusoe scheme under which insurance institution is entirely absent. For the first time in the literature, we characterize the condition, in terms of key parameters for valuating VOT, under which VOT may increase, decline, or even display more complicated profiles, as one ages. Our analysis reveals the crucial role played by the relative magnitude of the market interest rate to other parameters (including the parameter of time preference, the age-specific mortality and the wage growth rate) in determining the age profile of VOT, and the difference in VOT that is caused by the insurance scheme.      

Private,Social, and Self‐Insurance for Long‐Term Care in the Presence of Family Help

We study the political determination of the level of social long‐term care insurance when voters can top up with private insurance, saving and family help. Agents differ in income, probability of becoming dependent and of receiving family help, and amount of family help received. Social insurance redistributes across income and risk levels, while private insurance is actuarially fair. The income‐to‐dependency probability ratio of agents determines whether they prefer social or private insurance. Family support crowds out the demand for both social and, especially, private insurance, as strong prospects of family help drive the demand for private insurance to zero. The availability of private insurance decreases the demand for social insurance but need not decrease its majority‐chosen level. A majority of voters would oppose banning private insurance.     

QUANTIFYING THE LAFFER CURVE ON THE CONTINUED ACTIVITY TAX IN A DYNASTIC FRAMEWORK*

It is argued that the tax on continued activity should be removed by implementing actuarially fair schemes. However, these schemes cannot fund the expected Social Security (SS) deficit. This article proposes to give individuals a fraction of the actuarially fair incentives in the case of postponed retirement. SS faces a trade‐off between giving enough incentives to make individuals delay retirement and giving little increase in pensions in order to help finance its expected deficit. This trade‐off is captured by a Laffer curve. Finally, when the SS system aims to maximize welfare, the optimal tax on postponed retirement is still strictly positive.     

The impact of the correlation between health expenditure and survival probability on the demand for insurance

This paper studies the effects of health shocks on the demand for health insurance and annuities, along with precautionary saving in a dynamic life-cycle model. I argue that when the health shock can simultaneously increase health expenses and reduce longevity, rational agents would neither fully insure their uncertain health expenses nor fully annuitize their wealth because the correlation between health expenses and longevity provides a self-insurance channel for both uncertainties. That is, when the agent is hit by a health shock (which simultaneously increases health expenses and reduces longevity), she can use the resources originally saved for consumption in the reduced period of life to pay for the increased health expenses. Since the two uncertainties partially offset each other, the precautionary saving generated in the model should be smaller than in a standard model without the correlation between health expenses and longevity. In a quantitative life-cycle model calibrated using the Medical Expenditure Panel Survey dataset, I find that the health expenses are highly correlated with the survival probabilities, and this correlation significantly reduces the demand for actuarially fair health insurance, while its impact on the demand for annuities and precautionary saving is relatively small.     

Insurance,credit, and technology adoption: Field experimental evidencefrom Malawi

Does production risk suppress the demand for credit? We implemented a randomized field experiment to ask whether provision of insurance against a major source of production risk induces farmers to take out loans to adopt a new crop technology. The study sample was composed of roughly 800 maize and groundnut farmers in Malawi, where by far the dominant source of production risk is the level of rainfall. We randomly selected half of the farmers to be offered credit to purchase high-yielding hybrid maize and groundnut seeds for planting in the November 2006 crop season. The other half of farmers were offered a similar credit package, but were also required to purchase (at actuarially fair rates) a weather insurance policy that partially or fully forgave the loan in the event of poor rainfall. Surprisingly, take-up was lower by 13 percentage points among farmers offered insurance with the loan. Take-up was 33.0% for farmers who were offered the uninsured loan. There is suggestive evidence that reduced take-up of the insured loan was due to farmers already having implicit insurance from the limited liability clause in the loan contract: insured loan take-up was positively correlated with farmer education, income, and wealth, which may proxy for the individual's default costs. By contrast, take-up of the uninsured loan was uncorrelated with these farmer characteristics.     

Social security is NOT a substitute for annuity markets

Common wisdom suggests that a fully-funded actuarially fair social security system should increase welfare when households face longevity risk and annuity markets are missing. This wisdom is based on the observation that social security pays benefits as life annuities and therefore appears to complete the market. However, we argue that common wisdom is based on a benefit-only analysis that ignores a fundamental cost—social security crowds out the bequests that households leave (and receive) in general equilibrium. We conduct a general equilibrium cost-benefit analysis of the longevity insurance role of social security, and we show that under certain conditions this decline in bequest income offsets any possible gains from access to a public annuity pool. We abstract from distortions to national income and factor prices to show that the equilibrium bequest channel is all that is needed to reach this conclusion.     

Can a Mixed Health Care System be Desirable on Equity Grounds?*

Should health care provision be public, private, or both? We consider this question in a setting where people differ in their earnings capacity and face some illness risk. We assume that illness reduces an individual's time endowment when waiting for treatment. Treatment can be obtained in a competitive private sector (through private insurance) or in the National Health Service (NHS) where it is provided free of charge but after some (endogenous) waiting time. The equilibrium in the health care sector consists of a waiting time in the NHS such that no patient wants to switch health care provider. This equilibrium is governed by two public policies: the income tax system and the size of the NHS. We find that: (i) a mixed system with a small NHS is never desirable; (ii) actuarially fair sickness insurance is never desirable either; (iii) a mixed system with a sufficiently large NHS may improve on a pure public system if the dispersion of earnings capacities is large enough; and (iv) the welfare gains from such a mixed system are not likely to be significant.     

Production and insurance under regret aversion

This paper examines the behavior of a regret-averse producer facing revenue risk. To insure against the revenue risk, the producer can purchase a coinsurance contract with an endogenously chosen coinsurance rate. Regret-averse preferences are characterized by a utility function that includes disutility from having chosen ex-post suboptimal alternatives. We show that the regret-averse producer never fully insures against the revenue risk even though the coinsurance contract is actuarially fair. When the producer is sufficiently regret averse and the loss probability is high, we further show that the regret-averse producer chooses not to purchase the actuarially fair coinsurance contract. Even when purchasing the actuarially fair coinsurance contract is optimal, we derive sufficient conditions under which the regret-averse producer reduces the optimal output level as compared to that without the coinsurance contract. These results are distinct from those under pure risk aversion, thereby making the consideration of regret aversion crucial.     

Episodic flooding and the cost of sea-level rise

Previous studies of the cost of sea-level rise focus on the economic loss to inundated property rather than increased damage from episodic flood events to non-inundated property above sea level. This study uses a unique GIS database of three geographically diverse Chesapeake Bay communities that includes 1-ft elevation contours from remote sensing data, local tax assessment records, and aerial photographs of property location. Hedonic property value models estimate the loss from complete inundation, closely following the methodology of previous studies. Increased damage from episodic flooding is estimated using elevation-rated, actuarially fair flood insurance rates. Using a 3-ft sea-level rise over 100 years scenario, damage from episodic flooding averages 9 times the estimated loss from complete inundation, and is an average of 28 times greater under a 2-ft sea-level rise scenario. Although the study areas are not representative of all coastal areas, the results suggest that current studies may substantially underestimate the cost of sea-level rise.     

我国寿险公司范围经济效应的实证研究

我国自1996年实施产寿分业经营以来,人身保险业务快速增长,寿险公司数量急剧增加,寿险公司业务中新型寿险的比重不断上升,呈现出"一险独大"的市场状况。运用超越对数成本函数,对国内29家具有代表性的寿险公司2005-2010年期间的范围经济状况进行检验的结果显示:不同规模和背景的寿险公司的范围经济系数均比较明显,但是很多寿险公司所表现出来的范围经济性具有"欺骗性"。因此,寿险业务结构调整缺乏内部的市场激励,需要强有力的外部力量推动。     

ASSET‐BASED UNEMPLOYMENT INSURANCE*

This article studies a model of consumption, savings, and job search in which a borrowing constraint limits self‐insurance. The government administers the unemployment insurance program that may condition on an individual’s asset position, but not on her efforts of finding a job. To compensate for the impediments to self‐insurance, benefit payments should optimally be set higher at lower wealth levels and peak for borrowing‐constrained individuals with zero liquid funds. A quantitative exercise reveals that the U.S. unemployment insurance program is surprisingly close to optimal for the asset poor, but far too generous for wealthier individuals.     

Reforming occupational pension schemes: the case of the Netherlands

In many countries, occupational plans are being reformed away from defined-benefit (DB) to defined-contribution (DC) designs. This paper explores the case of the Netherlands, which features a particularly high ratio of occupational pension assets to GDP. Dutch occupational DB plans suffer from a number of serious weaknesses, including ambiguous ownership of assets, back-loading of benefits, and lack of tailor-made risk management. To address these weaknesses, we propose collective individual DC plans that are actuarially fair. These schemes maintain important strengths of collective schemes, such as mandatory saving, collective procurement, and pooling of biometric risks. At the same time, they eliminate intergenerational conflicts about risk management and distribution through transparent individual property rights on financial assets and tailor-made risk profiles in individual accounts. We show how the transitional burden due to phasing out the back-loading of pension benefits can be addressed without a substantial increase in contributions.     

Risk aversion and self-insurance

This paper considers the effects of an increase in risk aversion on self-insurance. More risk-averse individuals invest more in self-insurance in the case of two states of the world. However, with more than two states, this standard conclusion does not hold. The reason is that self-insurance does not necessarily reduce larger losses more effectively than smaller losses. Self-insurance thus may not serve as insurance, and more risk-averse individuals may invest more or less in self-insurance. The paper provides a condition for more risk-averse individuals to invest more in self-insurance, and a condition for them to invest less.     

Insurance with Frequency Trading: A Dynamic Analysis of Efficient Insurance Markets

This paper extends existing insurance results on the type of insurance contracts needed for insurance market efficiency to a dynamic setting. It introduces continuously open markets that allow for more efficient asset allocation. It also estimates the role of preferences and endowments in the classification of risks, which is done primarily in terms of the actuarial properties of the underlying risk process. The paper further extends insurability to include correlated and catastrophic events. Under these very general conditions the paper defines a condition that determines whether a small number of standard insurance contracts (together with aggregate assets) suffice to complete markets or one needs to introduce such assets as mutual insurance. Journal of Economic Literature Classification Numbers: D81, D99, G11.     

ENTREPRENEURSHIP AND JOB LOCK: THE INTERACTION BETWEEN TAX SUBSIDIES AND HEALTH INSURANCE REGULATIONS

This paper demonstrates that health insurance tax subsidies increase self‐employment, but that the effect differs substantially based on nongroup market regulations and health status. Using the Panel Study of Income Dynamics, I show that households that cannot purchase health insurance because of a preexisting condition do not respond to tax subsidies in states in which they would be denied insurance, but they respond strongly in states in which they face risk‐rated premiums. Households respond similarly to tax subsidies in states with nongroup market regulations similar to those established by the Affordable Care Act, regardless of preexisting conditions. (JEL H20, I13, J30)     

Taxation,insurance, and precautionary labor

We examine optimal taxation and social insurance with adverse selection in competitive insurance markets. In a previous literature, it has been shown that, with perfect insurance markets, social insurance improves welfare since it is able to redistribute without creating distortions. This result has been taken as robust to the introduction of adverse selection as this would only provide additional justifications for social insurance. We show, however, that adverse selection can weaken the case for social insurance compared to a situation with perfect markets. Whenever social insurance mitigates private underinsurance, it also causes welfare-reducing effects by decreasing precautionary labor supply and hence tax revenue. In addition, adverse selection may reduce the redistributive potential of social insurance. We illustrate our general results using different equilibrium concepts for the insurance market. Notably, we derive conditions under which a complete renunciation of social insurance is optimal and the government only relies on income taxation to achieve its redistributive objectives.     

The effect of unemployment insurance on the riskiness of occupational choice

This paper examines the effect of unemployment insurance on the riskiness of occupational choice by postulating a model of job search in which job offers have two characteristics; their wage and their security of tenure. Two versions are considered: a general case in which the unemployment benefit is earnings-related, and a special case in which the benefit is of a flat-rate form. Of particular interest in the paper is the individual's desired trade-off between wage and security of tenure, and how this trade-off is affected by the type of insurance scheme in operation. Perhaps surprisingly, we find that an earnings-related scheme encourages risk-taking behaviour by the poor, and risk-avoiding behaviour by the rich; in contrast, a flat-rate scheme neither encourages nor discourages risk-taking.     

Weather Index Drought Insurance: An Ex Ante Evaluation for Millet Growers in Niger

In the Sudano-Sahelian region, which includes South Niger, the inter-annual variability of the rainy season is high and irrigation is limited. As a consequence, bad rainy seasons have a massive impact on crop yield and regularly result in food crises. Traditional insurance policies based on crop damage assessment are not available because of asymmetric information and high transaction costs compared to the value of production. We assess the risk mitigation capacity of an alternative form of insurance which has been implemented at a large scale in India since 2003: insurance based on a weather index. We compare the efficiency of various weather indices to increase the expected utility of a representative risk-averse farmer. We show the importance of using plot-level yield data rather than village averages, which bias results due to the presence of idiosyncratic shocks. We also illustrate the need for out-of-sample estimations in order to avoid overfitting. Even with the appropriate index and assuming substantial risk aversion, we find a limited gain of implementing insurance, which roughly corresponds to, or slightly exceeds, the cost observed in India for implementing such insurance policies. However, when we separately treat the plots with and without fertilisers separately, we see that the benefit of insurance is slightly higher in the former case. This suggests that insurance policies may slightly increase the use of risk-increasing inputs such as fertilisers and improved cultivars, and hence improve average yields, which remain very low in the region.