Indeterminacy in dynamic models: When Diamond meets Ramsey

We consider an aggregate two-periods overlapping generations model with endogenous labor, consumption in both periods of life, homothetic preferences and productive external effects coming from the average capital and labor. We show that under realistic calibrations of the parameters, in particular a large enough share of first period consumption over the wage income, local indeterminacy of equilibria cannot occur with capital externalities alone. It can nevertheless occur when there are only, even very small, vanishing labor externalities provided that the elasticity of capital-labor substitution and the wage elasticity of the labor supply are large enough. We also show that if labor externalities are slightly stronger, but still small enough to be plausible, and the elasticity of labor supply is larger, local indeterminacy occurs in a Cobb-Douglas economy. Finally, we show that a locally indeterminate steady state is generically characterized by an under-accumulation of capital. It follows therefore that while agents live over a finite number of periods, the conditions for the existence of locally indeterminate equilibria are very similar to those obtained within infinite horizon models and that from this point of view, Diamond meets Ramsey.     

Sunspot Fluctuations in Two-sector Economies with Heterogeneous Agents

We study a two-sector model with heterogeneous agents and borrowing constraint on labor income. We show that the relative capital intensity difference across sectors is crucial for the conditions required to get indeterminacy and endogenous fluctuations. The main result shows that when the consumption good is sufficiently capital intensive, local indeterminacy arises while the elasticities of capital–labor substitution in both sectors are slightly greater than unity and the elasticity of the offer curve is low enough. Locally indeterminate equilibria are thus compatible with a low elasticity of intertemporal substitution in consumption and a low elasticity of the labor supply. As recently shown in empirical analysis, these conditions appear to be in accordance with macroeconomic evidences. We would like to thank R. Becker, J.P. Drugeon and an anonymous referee for useful comments and suggestions. The current version also benefited from a presentation at the conference “Public Economic Theory 04”, Beijing, August 2004.     

Can consumption habit spillovers be a source of equilibrium indeterminacy?

This paper investigates whether the external consumption habit can be a source of indeterminacy in a one-sector growth model when the labor supply is elastic. When there is a proper habit effect with a positive intertemporal elasticity of substitution, we find that the model exhibits indeterminacy if the coefficient of the habit formation is sufficiently large that allows for a substantial impact of current consumption on the habit. Indeterminacy arises even though the elasticity of the Frisch labor supply is positive and the elasticity of the labor demand in negative. In a calibrated version, we find that indeterminacy is empirically plausible when the habit effect is negative that features the “catching up with the Joneses” effect. Under given “catching up with the Joneses” effects, the external consumption habit can be a source of indeterminacy even if more than a half of the external consumption habit comes from past average consumption.     

Stabilization policy and indeterminacy in a small open economy

This paper studies the (de)stabilizing effects of income tax rules in a two-sector small open economy with production externalities. The paper shows that in the model with positive sector-specific externalities in the investment sector and negative sector-specific externalities in the consumption sector (or positive aggregate investment externalities), a regressive income tax rule can stabilize such an economy against indeterminacy, whereas a progressive income tax rule can increase the tendency for indeterminacy to occur. This paper also studies two variants that consider an imperfect world bond market and an endogenous labor supply, respectively, and shows that the qualitative results stated above remain valid. Moreover, increasing the level of sector-specific investment externalities can decrease (increase) the minimal level of tax progressivity required for indeterminacy if the investment externalities are below (above) a certain critical value and if the negative externalities in the consumption sector are taken as given.     

Indeterminacy in a small open economy with endogenous labor supply

Summary. We establish conditions under which indeterminacy can occur in a small open economy business cycle model with endogenous labor supply. Indeterminacy requires small externalities in technologies with social constant returns to scale, independently of the intertemporal elasticities in both consumption and labor. Received: December 12, 2001; revised version: May 17, 2002 RID="*" ID="*"The paper has benefited from discussions with Jess Benhabib and Mark Weder, as well as from the comments of an anonymous referee. Correspondence to: Q. Meng     

Intertemporal production and intertemporal substitution in output supply and input demand

This article presents an intertemporal model of production with multiple inputs to investigate substitution opportunities facing firms over time. The firm’s intertemporal profit maximization problem is characterized with the familiar cost function, and various intertemporal substitution elasticities are delineated for output supply and input demand. The absence of intertemporal substitution in production can imply production smoothing, and allowance for intertemporal substitution in labour demand reinforces the prediction of the real business cycle model. For aggregate US manufacturing, we find substantial substitution in output supply and labour demand over time due to intertemporal changes in output price and wage rates.     

Superneutrality, indeterminacy and endogenous growth

In this paper, we explore the possibility of having money as a source of indeterminacy in endogenous growth models. We adopt the simple Ak model of endogenous growth to be the main analytical vehicle whose balanced growth paths do not display local indeterminacy. Money is introduced via either a general cash-in-advance (CIA) constraint or a pecuniary transactions costs (PTC) technology. It is shown that local indeterminacy of the dynamics is due to the presence of an intertemporal substitution effect on capital accumulation that works against and dominates the conventional inflation effect of Tobin [1965, Money and economical growth. Econometrica 33(4), Part 2, 671]. If money is growth-rate superneutral, then the intertemporal substitution effect is absent so that local indeterminacy cannot occur. Finally, the strength of the intertemporal substitution effect depends positively on the intertemporal elasticity of substitution in consumption.     

On the long-run wealth distribution in a simple Ramsey model with heterogeneous households

This paper analyzes the long-run wealth distribution in a Ramsey model where individuals have a common rate of time preference but different intertemporal elasticities of substitution. As a result, it is shown that heterogeneity among households in intertemporal substitution is sufficient for the existence of a non-degenerate long-run wealth distribution. We also investigate the properties of the long-run wealth distribution and the transition of capital and consumption using the phase diagram.     

Intertemporal labor supply and involuntary unemployment

We estimate a model of intertemporal male labor supply behavior which explicitly accounts for the effect of income taxation and the transfer system. Moreover, we model the demand-side driven rationing risk that prevents agents from choosing the optimal labor supply state. Our results show that elasticities derived in an unconstrained pure choice model are significantly higher compared to a model with involuntary unemployment. This holds true for short-run and long-run labor supply elasticities.     

Fiscal policy and indeterminacy in models of endogenous growth

This paper investigates the dynamic behavior of two-sector models of endogenous growth with sector-specific external effects, and government expenditure financed by distortionary taxation. When this type of external effect is combined with a sufficient degree of capital taxation in a Lucas-Uzawa endogenous growth model, continua of equilibria will emerge in the region of the balanced growth paths. By contrast, indeterminacy is not possible when either sector-specific external effects or factor taxation are added to the model in isolation. In the second part of the paper, we demonstrate that if labor supply is endogenous, indeterminacy can be consistent with much lower degrees of increasing returns to scale. Furthermore, certain types of fiscal policy will be associated with multiple balanced growth paths and the existence of a poverty trap. Finally, in the last part of the paper, we demonstrate that if physical capital is employed in both sectors of the economy, indeterminacy will emerge for varying combinations of factor taxation and external effects, even when returns to scale are constant at the social level.     

Implementing Steady State Efficiency in Overlapping Generations Economies with Environmental Externalities

We consider in this paper overlapping generations economies with pollution resulting from both consumption and production. The competitive equilibrium steady state is compared to the optimal steady state from the social planner's viewpoint. We show that the dynamical inefficiency of a competitive equilibrium steady state with capital–labor ratio exceeding the golden rule ratio still holds. Moreover, the range of dynamically efficient steady state capital ratios increases with the effectiveness of the environment maintenance technology, and decreases for more polluting production technologies. We characterize some tax and transfer policies that decentralize as a competitive equilibrium outcome the transition to the social planner's steady state.     

Indeterminacy with no-income-effect preferences and sector-specific externalities

We examine a two-sector real business cycle (RBC) model with sector-specific externalities in which household utility exhibits no income effect on the demand for leisure. Unlike in the one-sector counterpart, indeterminacy can result with sufficiently high returns-to-scale in the investment sector. Moreover, the smaller the labor supply elasticity, the lower the level of externalities needed for indeterminacy. This finding is the opposite of that in all existing RBC-based indeterminacy studies. Finally, in contrast to previous sunspot-driven two-sector RBC models, our economy is able to match the stylized facts that sectoral labor inputs are positively correlated and consumption is procyclical.     

Commodity Rates of Interest and Intertemporal Substitution in Commodity Demand and Consumption

This paper examines the role of commodity own rates of interest in intertemporal analysis of consumer behaviour and presents a disaggregate analysis of intertemporal substitution in commodity demand and consumption. Commodity rates of interest are defined from the Euler equations implied by the intertemporal consumer choice problem. The relationship between commodity own rates and the real interest rate is derived, and the conditions for equality of commodity own rates are discussed. The intertemporal commodity substitution elasticities are characterised using commodity rates of interest, and the intertemporal substitution elasticity of consumption is derived from its constituent commodity demands. Evidence from estimation of the demand system and the consumption function reveals high intertemporal substitution for consumer goods as well as consumption.     

Renewable Resource Use and Nonseparable Amenity Benefits

We incorporate amenity benefits into an overlapping generations model with a renewable resource as a factor of production, source of amenity benefits and store of value. Unlike the conventional renewable resource problems studied under the assumption of additive consumption and amenity benefits, we let amenity benefits affect the utility of consumers in a nonseparable fashion. We examine the role that weights given to consumption and amenities have for harvesting and the resource stock. We characterize dynamics and stability of steady state equilibria with a logistic resource growth function. We demonstrate in parametric and numerical models that the weights given to consumption and amenities in the utility function matter substantially for the steady state equilibrium stock and its stability and dynamics. Both conventional saddle point equilibria and indeterminacy with infinite number of equilibria and saddle-node bifurcation is possible depending on the weights given to consumption and amenities. In addition, we show that for each inefficient equilibrium stock, there is a unique subsidy rate that can move the economy from an inefficient equilibrium to an efficient one. The presence of indeterminacy provides a challenge to resource policies, because the system becomes unpredictable. Therefore, expectations and market psychology may play an important role in resource utilization and provision of amenities.     

Balanced‐Budget Rules,Elasticity of Substitution,and Macroeconomic (In)Stability

This paper examines the relation between factor substitution and (local) stability of equilibria in a one‐sector real business cycle model under balanced‐budget rules. We show that under non‐unitary elasticity of factor substitution, the Schmitt‐Grohé‐Uribe indeterminacy result can be altered. Using the two‐step normalization procedure, we highlight two opposing effects of factor substitution, namely, the efficiency effect and the distribution effect, on aggregate stability. With endogenous distortionary taxes and gross substitutability between capital and labor, the existing literature overlooks the distribution effect and finds that balanced‐budget rules are likely to deliver indeterminacy. However, if capital stock is relatively more abundant, a higher elasticity of substitution generates a source of stability due to the distribution effect. Our calibration shows that the distribution effect is always the dominating force.     

Indeterminacy Arising in Multi-sector Economies

We characterize a large class of constant-returns-to-scale economies with standard Cobb–Douglas production technologies, which, when perturbed to incorporate external effects, exhibit indeterminacy or multiple equilibria. The perturbations are constrained to maintain overall constant returns to scale. We characterize the magnitude of the external effects that yield multiple equilibria in terms of the parameters of the unperturbed economy. We show that it is very easy to construct large and plausible classes of economies that exhibit indeterminacy with constant returns to scale, and with external effects that are arbitrarily small.
JEL Classification Numbers: E00, E3, O40.     

Wealth inequality, preference heterogeneity and macroeconomic volatility in two-sector economies

We explore the link between wealth inequality, preference heterogeneity and macroeconomic volatility in a two-sector neoclassical growth model. First we prove that, if agents have homogeneous preferences, when the absolute risk tolerance is a strictly convex (concave) function, sufficiently high (low) levels of wealth inequality may lead to endogenous fluctuations in the neighborhood of the steady state. Second, we consider the effects of preference heterogeneity when agents are homogeneous with respect to their wealth. We show that when the utility function belongs to the HARA class, sufficiently high levels of preference heterogeneity may lead to endogenous fluctuations in the neighborhood of the steady state if the elasticity of intertemporal substitution in consumption is greater than one.     

Empirical demand systems incorporating intertemporal consumption dynamics

This article presents and estimates demand systems by explicitly incorporating intertemporal consumption behavior as summarized by the Euler equation. Demand systems are characterized by two indirect utility functions which are effectively globally regular and can better approximate nonlinear Engel curves. Furthermore, an exact and nonlinear Euler equation is derived without a log approximation. This equation is estimated jointly with the demand functions by a careful implementation of the orthogonality conditions using generalized method of moments. We illustrate the techniques by estimating the demand system and Euler equation for Australian aggregate data. Results generally indicate that the proposed methods are promising. The estimated rate of time preference is fairly small while the restrictions producing the moment equations are not rejected. Estimated Frisch price elasticities, which are relevant in an intertemporal setting, appear reasonable, and the intertemporal elasticity of substitution for consumption is found to be small, which are consistent with the findings in earlier studies.     

Asymmetric Factor Substitutability and Indeterminacy

We consider a discrete-time two-sector CES economy with sector specific external effects in which factor substitutability differs across sectors. For this general model, we provide sufficient conditions on the elasticities of capital/labor substitution for local indeterminacy of equilibria.Acknowledgement We would like to thank two anonymous referees, the editor Dieter Bös and Tapan Mitra for comments on an earlier version of this paper, previously entitled Capital Depreciation, Factors Substitutability and Indeterminacy, which allowed us to improve considerably the results.     

Labor income,borrowing constraints,and equilibrium asset prices

Summary We develop a duality approach to study an individual's optimal consumption and portfolio policy when the individual has limited opportunities to borrow against future labor income and cannot totally insure the risk of income fluctuations. The individual's intertemporal consumption and portfolio problem is cast in a continuous-time setting under uncertainty. We transform the individual's intertemporal problem into a dual shadow prices problem that solves the shadow prices for the individual's optimal consumption plan or equivalently the individual's intertemporal marginal rates of substitution. We show that the shadow prices process can be expressed as a product of a martingale and a decreasing process (normalized by the bond price). The existence of an optimal solution to the individual's intertemporal consumption and portfolio problem is established via duality. The duality approach also allows us to characterize in a sample way the individual's optimal consumption and portfolio policy in the presence of labor income and borrowing constraints. Equilibrium implications of borrowing constraints on asset prices are also discussed in the paper.This is a revised version of an earlier paper, entitled Consumption and Portfolio Decisions with Labor Income and Borrowing Constraints. We thank George Constandinides, Ayman Hindy, and Chi-fu Huang for helpful comments. We also thank two anonymous referees for their helpful comments and suggestions. Financial support from the Batterymarch Fellowship Program (for Hua He) is gratefully acknowledged.