Multiple solutions under quasi-exponential discounting

Infinite horizon dynamic optimization problems with non-exponential time preferences may not only exhibit time inconsistency but may also have multiple solutions with distinct payoffs. We here show that such multiplicity is generic in the sense that it occurs in an open set of such decision problems, even with small state- and action-spaces. Non-exponential discounting allows for an “addictive” equilibrium alongside a “virtuous” equilibrium. We also provide a sufficient condition for uniqueness in infinitely repeated decision problems with general action spaces. Authors thank Philippe Jehiel, Maria Saez-Marti and Bill Sandholm for comments to an earlier version, and the Knut and Alice Wallenberg Research Foundation for financial support.     

Hyperbolic discounting and the standard model: Eliciting discount functions

Experiments on static intertemporal choice find evidence of particularly extreme impatience toward immediate rewards. While this is often taken as support for hyperbolic discounting, it could also arise because the most likely participants in experiments may be those with the most immediate need for money. We conduct a calibration exercise and find that the extreme impatience observed in experiments can be accommodated by a standard exponential discounting model with no discounting and expectation of a ‘small’ increase in the base consumption level. The calibration uses existing estimates of curvature of utility.     

贴现因子、偏好和行为经济学

本文讨论了影响人们跨时选择的重要因素--贴现因子的最新进展以及他们在经济学和金融中的重要应用,给出了目前关于改变贴现因子的模型.     

Intertemporal Effects of Environmental Mandates

Environmental mandates can impose large costs on the businesses that must comply with them. Understanding the effects of those costs on production decisions may require a dynamic framework if environmental damages (and the costs of complying with mandates) depend on cumulative production or the passage of time. This paper focuses on the time dimension of general categories of fixed and variable costs arising from different types of mandates. The paper develops an optimal control model to predict how such costs may jointly affect current production rates, plant closure dates, and cumulative production. Theoretical results, derived from the comparative statics of the system of equations describing the solution to that model, identify circumstances in which the policy goals of greater production and greater environmental protection may not allways be at odds. Statements in this paper do not reflect the views or positions of the Congressional Budget Office     

国际宏观经济学理论与最新进展

国际宏观经济学是研究开放经济条件下的宏观经济的一门较新的学科,其主要发展体现在战后时期。经历了凯恩斯主义、货币主义等理论,今天的国际宏观经济学体现为对以往理论的综合和发展。本文简要回顾国际宏观经济学领域的理论发展脉络以及发展推动力,并对一个最新的代表性主体跨时最优模型进行分析,借此展望国际宏观经济学的发展规律以及对未来的发展前景。     

Why Excel?

Advanced Placement economics leaves thousands of high school students with a misleading impression of modern economics. The courses fail to cover key sources of growth and prosperity, including private ownership, dynamic competition, and entrepreneurship. The tools of public choice economics are totally ignored. Government is modeled as a corrective device available to impose ideal solutions. Market failure is covered, but there is no such thing as government failure. The macroeconomics course reflects the simplistic 1960s Keynesian view of stabilization policy. Time lags, incentive effects, secondary effects of budget deficits, and other factors that complicate effective use of stabilization policy are almost entirely ignored. In contrast, the 20 Voluntary National Content Standards in Economics of the Council for Economic Education illustrate what a balanced course in modern economics would look like.     

Demographics and Behaviour

Using a unique experimental subject pool, I analyse the behaviour of subjects in a life-cycle consumption experimental task. As in previous experiments, it is clear that different subjects solve the task differently – some having strategies close to the fully optimal and others using simple heuristics. The nature of my subject pool enables me to see if there is any link between the strategies employed by the subjects and their demographic characteristics. I also explore whether the parameters in the task influence the chosen strategy. I find little systematic demographic influence. The results of the paper have an important message concerning the representativeness of typical subject pools used in economics experiments.JEL Classification: C91, D91     

Overconfidence and consumption over the life cycle

Overconfidence is a widely documented phenomenon. In this paper, we study the implications of consumer overconfidence in a life-cycle consumption/saving model. Our main analytical result is a necessary and sufficient condition under which any degree of overconfidence concerning the mean return on savings can produce a hump in the work-life consumption profile. This condition is almost always met in the data. We show by simulations that overconfidence concerning the variance of the return can have little effect on the long-run average behavior of consumption over the life cycle, and that our basic conclusion is fairly robust with various realistic modifications to the baseline model. We interpret the general applicability of our analytical framework and discuss our numerical results in the light of aggregate consumption data.     

The Nature of the State and the State of Nature: a Comment on Grady & McGuire's Paper

In 'The Nature of Constitutions', Mark Grady & Michael McGuire provide a model of the evolution and purposes of constitutions as arising to minimize appropriation by dominants of subordinates. This Comment builds on Grady & McGuire's article in three ways. First, it supplements their analysis by operationalizing a model of constitutional evolution that views constitutions as arising out of the conflict of competing high-ranking individuals to preserve their own authority. From this clash of self-interest of dominant individuals, constitutions are born. This predicts that constitutions will not simply tame all forms of appropriation, but will also hard-wire some forms of appropriation behavior into the permanent constitutional structure. Second, it examines the American constitution in light of this model to show how that constitution reflects the mixture of appropriation and appropriation-taming behavior. Third, this Comment argues that the breakdown of constitutionalism in the United States this century can be explained by a failure to fully appreciate the purposes of constitutionalism in a biological framework.     

Precautionary savings of agents with heterogeneous risk aversion

This article focuses on the estimation of the importance of the precautionary motive in the wealth accumulation decision. We use the micro data set of the De Nederlandsche Bank (DNB) Household Survey (DHS) (CentERdata, Tilburg University), a Dutch household survey containing information on wealth, a subjective measure of income uncertainty and subjective qualitative measures of risk aversion. We find that only a small share of wealth is accumulated for the precautionary motive by the Dutch households. This share of wealth is constant across assets with different degrees of liquidity. The economic downturn of the period 2008 to 2010 seems to affect risk attitudes and precautionary saving. Our findings also suggest that the more risk-averse individuals are those who hold less savings.     

Robust political economy

This paper introduces the idea of “robust political economy.” In the context of political economic systems, “robustness” refers to a political economic arrangement's ability to produce social welfare-enhancing outcomes in the face of deviations from ideal assumptions about individuals' motivations and information. Since standard assumptions about complete and perfect information, instantaneous market adjustment, perfect agent rationality, political actor benevolence, etc., rarely, if ever actually hold, a realistic picture and accurate assessment of the desirability of alternative political economic systems requires an analysis of alternative systems' robustness. The Mises-Hayek critique of socialism forms the foundation for investigations of robustness that relax ideal informational assumptions. The Buchanan-Tullock public choice approach complements this foundation in forming the basis for investigations of robustness that relax ideal motivational assumptions. JEL Code B53, P16, P26