Optimal interest rate stabilization in a basic sticky-price model

This paper studies optimal monetary policy with the nominal interest rate as the single policy instrument. Firms set prices in a staggered way without indexation and real money balances contribute separately to households’ utility. The optimal deterministic steady state under commitment is the Friedman rule—even if the importance assigned to the utility of money is small relative to consumption and leisure. We approximate the model around the optimal steady state as the long-run policy target. Optimal monetary policy is characterized by stabilization of the nominal interest rate instead of inflation stabilization as the predominant principle.     

Testing the Empirical Relevance of the ‘Saving for a Rainy Day’ Hypothesis in US Metro Areas

The joint implication of the consumption Euler equation and cointegration between income and consumption is that savings predict future income declines, the ‘saving for a rainy day’ hypothesis. The empirical relevance of this hypothesis plays a key role in discussions of fiscal policy multipliers, and it holds under the null that the permanent income hypothesis is true. We find little support for this hypothesis using time series data for the 100 largest US Metropolitan Statistical Areas for the period 1980q1–2015q4. Our approach is to test for cointegration and weak exogeneity between income and consumption, and by exploring the direction of Granger causality between the two time series. We find that income more often predicts consumption and saving than the converse. We also give evidence that house price changes played a role in US income and consumption dynamics, before, during and after the Great Recession.     

Central-city income redistribution and the flight to the suburbs: A stylized model

This paper characterizes the optimal tax policy of a central-city government whose goal is to redistribute income from the rich to the poor to maximize the intertemporal utility of the latter group. Since redistribution erodes the tax base by stimulating suburban flight on the part of the rich, choosing the optimal path for the income tax rate is a problem in optimal control. The nature of the solution to the problem is shown to depend crucially on the level of the discount rate and the time path of exogenous income for the poor.     

A two sector endogenous growth model with habit formation

In this paper, we study an endogenous growth model with physical and human capital in which consumption habits enter the utility function multiplicatively. We show that although the utility function with multiplicative habits is nonconcave and unbounded, an interior optimal growth path still exists, it is uniquely determined and it converges to a balanced growth path. We also find that habit formation in consumption lowers the convergence speed of the optimal path toward the balanced growth path.     

Spatial differentiation,divisible consumption and the pro-competitive effect of income

We analyze a spatial differentiation model with divisible consumption under one-stop shopping. Each consumer who visits only one store, chooses the quantities of the goods which maximize his/her utility function under the budget constraint (namely consumption expenditures must equal income minus transportation costs), choosing the store which provides him/her with the largest indirect utility. We derive the equilibrium price when the firms are located at the two extremities of Hotelling’s linear city and show that income increases have a pro-competitive effect.     

Competitive equilibrium cycles with endogenous labor

In this paper, we study a two-sector optimal growth model with elastic labor supply. We show that the modified golden rule is saddle-point stable when the investment good is capital intensive. To characterize stability with a capital intensive consumption good, we focus on either additively separable or homothetic preferences. In the first specification, we show that optimal oscillations require the elasticity of intertemporal substitution in consumption to be high enough while the elasticity of labor needs to be low enough. At the same time, we prove that with a linear utility in leisure the modified golden rule is always saddle-point stable. In the second specification for preferences, we show that the local dynamic properties of the optimal path depend instead on the shares of consumption and leisure into total utility. We prove that endogenous fluctuations are even more likely with homothetic preferences.     

A closed-form solution for the continuous-time consumption model with endogenous labor income

In this paper, we study the consumption, labor supply, and portfolio decisions of an infinitely lived individual who receives a certain wage rate and income from investment into a risky asset and a risk-free bond. Uncertainty about labor income arises endogenously, because labor supply evolves randomly over time in response to changes in financial wealth. We derive closed-form solutions for optimal consumption, labor supply and investment strategy. We find that deferring the retirement age stimulates optimal consumption over time and discourages optimal labor supply during the working life. We also find explicitly that optimal portfolio allocation becomes more ‘conservative’ when the individual approaches his prescribed retirement age. The effects of risk-aversion coefficients on optimal decisions are examined.     

Consumption paths under prospect utility in an optimal growth model

This paper studies the Cass-Koopmans-Ramsey model of optimal economic growth in the presence of loss aversion and habit formation. The representative agent's preferences for consumption can be gradually varied between the standard constant intertemporal elasticity of substitution (CIES) case and Kahneman and Tversky's prospect utility. We find that the transitional dynamics of optimal consumption paths differ distinctly from the standard model, in particular consumption smoothing is more pronounced. We also show that prospect utility can cause the economy to remain in a steady state with low consumption and low capital.     

Life‐Cycle Consumption and Children: Evidence from a Structural Estimation

I estimate by maximum likelihood a dynamic model of optimal intertemporal allocation of consumption in the presence of children using high‐quality Danish longitudinal data. The number and age of all children can affect the marginal utility of consumption while income uncertainty, credit constraints and postretirement motives also influence household behaviour. While I estimate that children have a surprisingly small effect on the marginal utility of non‐durable consumption, data simulated from the estimated model replicates similar correlations between log consumption growth and changing household composition as found in the Danish data and typically found in UK and US data. To reconcile the results with existing studies, I illustrate how ignoring precautionary motives increases the estimated importance of children. The results indicate that precautionary motives might play a larger role than children in explaining the observed consumption age profile.     

Asymptotic behavior and optimal properties of a consumption-investment model with variable time preference

This paper analyzes the convergence properties and the determination of an optimal consumption path in the consumption-investment model of Uzawa (1968). Sufficient conditions for the existence and uniqueness of the optimal path are presented. Components of the utility functional are recovered when the optimal path is piecewise affine. The model is applied to the determination of the interest rate and income distribution under time preference differentials.     

城市空间结构理论——单中心城市静态模型

首先介绍了在西方城市经济理论中被广泛接受的单中心城市空间结构静态模型。然后,利用比较静态分析方法(comparativestaticanalysis),分析区位、居民收入及交通费用(区位,居民收入及交通费用为模型的外生变量(exogenousvariable))对价格和房屋消费量(价格和房屋消费量为模型的内生变量(endogenousvariable))的影响。最后,理论模型通过引进一般住房生产函数,推导出土地价格及资本密度(即建筑高度)的空间变化规律。通过对城市经济模型进一步分析(对极值条件或解的微分解析分析)得出地价(地租),资本密度(或称容积率),人口密度的空间分布规律,这些规律对城市规划,城市政策,引进市场原则和价格机制来提高城市土地利用效率都有理论指导意义。     

Optimal taxation in an RBC model: A linear-quadratic approach

We reconsider the optimal taxation of income from labor and capital in the stochastic growth model analyzed by Chari et al. [1994. Optimal fiscal policy in a business cycle model. Journal of Political Economy 102, 617–652; 1995. Policy analysis in business cycle models. In: Cooley, T.F. (Ed.), Frontiers of Business Cycle Research. Princeton University Press, Princeton], but using a linear-quadratic (LQ) approximation to derive a log-linear approximation to the optimal policy rules. The example illustrates how inaccurate ‘naive’ LQ approximation – in which the quadratic objective is obtained from a simple Taylor expansion of the utility function of the representative household – can be, but also shows how a correct LQ approximation can be obtained, which will provide a correct local approximation to the optimal policy rules in the case of small enough shocks. We also consider the numerical accuracy of the LQ approximation in the case of shocks of the size assumed in the calibration of Chari et al. We find that the correct LQ approximation yields results that are quite accurate, and similar in most respects to the results obtained by Chari et al. using a more computationally intensive numerical method.     

Stochastic costly state verification and dynamic contracts

I consider a dynamic costly state verification environment in which a risk-averse agent enters into a contract with a risk-neutral principal. The agent has random income which is unknown to the principal but can be verified at a cost. The principal can commit to executing random verifications.I extend the standard recursive methods to study the problem and show that it is optimal to set verification probabilities strictly less than 1. If the agent׳s absolute risk aversion declines sufficiently slowly, the principal will use verification regardless of its cost. If the agent's income is verified then he would get consumption and continuation utility strictly higher than if his income were not verified.     

The consumption–investment decision of a prospect theory household: A two-period model

This study extends the literature on portfolio choice under prospect theory preferences by introducing a two-period life cycle model, where the sufficiently loss averse household decides on optimal consumption and investment in a portfolio with one risk-free and one risky asset. The optimal solution depends primarily on whether the household’s present value of the consumption reference levels is below, equal to, or above the present value of its endowment income. Reference levels below the endowment income are associated with the self-enhancement motive. In this case, the household avoids relative losses in consumption in any present or future state of nature (good or bad). As a result the degree of loss aversion does not directly affect optimal consumption and risk taking activity. Reference levels equal to the endowment income are associated with the belonging motive. An example would be a household comparing to others that belong to the same social class. In this case the household’s optimal consumption is the reference consumption and the household will not invest in the risky asset. Finally, reference levels above the endowment income are associated with the self-improvement motive (or high aspirations). For such high reference levels, households cannot avoid experiencing a relative loss in consumption, either now or in the future. As a result, loss aversion directly affects consumption and risky investment.     

Adaptive consumption behavior

In this paper we propose and study a theory of adaptive consumption behavior under income uncertainty and liquidity constraints. We assume that consumption is governed by a linear function of wealth, whose coefficients are revised each period by a procedure that places few informational or computational demands on the consumer. We show that under a variety of settings the procedure converges quickly to a set of coefficients with low welfare cost relative to a fully optimal nonlinear consumption function.     

Measuring the costs of children: parametric and semiparametric estimators1

How much additional income does a family with four children need to attain the same welfare level as a family with two children? And how much does a single person need compared to a childless couple? These questions are important in applied micro-economics and underlie public policy on, for example, social benefits and child allowances. In microeconomics, this is known as the problem of measuring equivalence scales. We estimate these scales using two types of subjective survey information. First, we use answers to survey questions on the income required to attain a given utility level. We compare the results for the usual linear model with semiparametric estimates, in which the functional form of the relationship between required income and family size and actual income is left unspecified. Second, we use answers to the question: how satisfied are you with actual household income? We present parametric and semiparametric estimates for ordered response models explaining this discrete variable. We find that according to the second type of information, costs of children are much larger than according to the first.     

Threshold preferences and the environment

In this article we study the implication of thresholds in preferences. To model this we extend the basic model of John and Pecchenino (1994) by allowing the current level of environmental quality to have a discrete impact on how an agent trades off future consumption and environmental quality. Thus, we endogenize the semi-elasticity of utility based on a step function. We find that for low (high) thresholds, environmental quality converges to a low (high) steady state. For intermediate levels it converges to a stable p-cycle, with environmental quality being asymptotically bounded below and above by the low and high steady state. As policy implications we study shifts in the threshold. Costless shifts of the threshold are always worthwhile. If it is costly to change the threshold, then it is worthwhile to change the threshold if the threshold originally was sufficiently low. Lump-sum taxes lead to a development trap and a proportional income tax should be preferred.     

Look before you leap: Why politicians may have a point to be hesitant about the gains from trade

Economists emphasize the welfare gains of unrestricted trade, but politicians worry about the income distribution effects of increased competition. We show that the welfare gains of a trade shock become ambiguous if inaccurate information hinders optimal income redistribution with distortionary policy instruments. To be sure about the net welfare outcome of a compensated trade shock, the government must know the size of the trade shock and the corresponding size of the policy instrument that is needed to generate a balanced budget. If this is not the case, politicians may have a point when being hesitant about the gains from trade.     

Optimal dynamic tax evasion

We study optimal dynamic tax evasion in the framework proposed by Lin and Yang (2001) and Dzhumashev and Gahramanov (2011) with some modifications: a more flexible utility function, a more realistic audit process, and a penalty function which can be defined both on evaded income and evaded taxes. In the former case the elasticity between tax rate and tax evasion is positive, unless the subsistence consumption level is higher than a given threshold. In the latter case the relationship is usually negative , but the value of elasticity depends on the form of absolute risk aversion. In particular we show that for increasing relative risk aversion, for a tax rate higher than 50%, the elasticity may even become positive. US data are consistent with IRRA preferences.     

加强高收入阶层的消费热点研究促进国民经济合理发展

通过提高居民收入来促进消费固然重要,但盘活高收入阶层的大量储蓄存款,寻找他们的新的消费热点、引导其消费投向,也是刺激消费需求的重要方面。根据消费热点的形成条件和特征,文章分析了高收入阶层消费热点形成的可能性,探索了他们的消费热点产品,并提出了相关的配套措施。