Carine Nourry

Indeterminacy in dynamic models: When Diamond meets Ramsey

In this paper, we consider an aggregate overlapping generations model with endogenous labour, consumption in both periods of life, homothetic preferences and productive external effects coming from the average capital and labour. 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 but that it can occur when there are only, however small, labour externalities. More precisely, under gross substitutability, the existence of multiple equilibria requires a large enough elasticity of capital-labour substitution and a large enough elasticity of the labour supply. We also show that if labour externalities are slightly stronger and the elasticity of labour supply is larger, local indeterminacy occurs in a Cobb-Douglas economy. Finally, we show that, as a consequence of our restriction on first period consumption, 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.

Aggregate instability under balanced-budget consumption taxes: A re-examination

We re-examine the destabilizing role of balanced-budget fiscal policy rules based on consumption taxation. Using a one-sector model with infinitely-lived households, we consider a specification of preferences derived from Jaimovich (2008) [14] and Jaimovich and Rebelo (2009) [15] which is flexible enough to encompass varying degrees of income effect. When the income effect is not too large, we show that there exists a Laffer curve, which explains the multiplicity of steady states, and that non-linear consumption taxation may destabilize the economy, promoting expectation-driven fluctuations, if the elasticity of intertemporal substitution in consumption is sufficiently larger than one and the tax rate is counter-cyclical with respect to consumption. Numerical illustrations also show that consumption taxation may be a source of instability for most OECD countries for a wide range of structural parametersʼ configurations. We finally prove the robustness of our conclusions if we consider a discrete-time setup.

Determinacy of Equilibrium in an Overlapping Generations Model with Heterogeneous Agents

We consider the determinacy of perfect foresight equilibrium near a steady state in an overlapping generations model with production and both altruistic and non altruistic agents having distinct utility functions. The proportions of each type of consumers is exogenously given. Such a model may be interpreted as both a particular case and an extension of the one considered by Muller and Woodford(1988) in which both finite and infinite lived agents coexist.

On Efficiency and Local Uniqueness in Two-Sector OLG Economies

We consider a two-sector overlapping generations model with homothetic preferences. Under standard conditions on technologies, upon large enough values for the share of first period consumption over the wage income, we prove that the dynamic efficiency and local uniqueness of the competitive equilibrium hold. On the contrary, for lower values of the share of first period consumption over the wage income which imply dynamic inefficiency of the steady state, local indeterminacy arises when the elasticity of intertemporal substitution in consumption is large enough.

ENDOGENOUS BUSINESS CYCLES IN OVERLAPPING-GENERATIONS ECONOMIES WITH MULTIPLE CONSUMPTION GOODS

We consider an overlapping-generations economy with two consumption goods. There are two sectors that produce a pure consumption good and a mixed good that can be either consumed or used as capital. We prove that the existence of Pareto-optimal expectations-driven fluctuations is compatible with standard sectoral technologies if the share of the pure consumption good is low enough. Following Reichlins [Journal of Economic Theory 40 (1986), 89–102] influential conclusion, this result suggests that some fiscal policy rules can prevent business-cycle fluctuations in the economy by driving it to the optimal steady state as soon as they are announced.

PUBLIC SPENDING AS A SOURCE OF ENDOGENOUS BUSINESS CYCLES IN A RAMSEY MODEL WITH MANY AGENTS

We introduce public spending, financed through income taxation, in the Ramsey model with heterogeneous agents. Public spending as a source of welfare generates more complex dynamics. In contrast to previous contributions focusing on similar models but with wasteful public spending, limit cycles through Hopf bifurcation and expectation-driven fluctuations appear if the degree of capital-labor substitution is large enough to be compatible with capital income monotonicity. Moreover, unlike frameworks with a representative agent, our results do not require externalities in production and are compatible with a weakly elastic labor supply with respect to wage.

Sunspot Fluctuations in Two-Sector Models with Variable Income Effects

We analyze a version of the Benhabib and Farmer (1996) two-sector model with sector-specific externalities in which we consider a class of utility functions inspired from the one considered in Jaimovich and Rebelo (2009) which is flexible enough to encompass varying degrees of income effect. First, we show that local indeterminacy and sunspot fluctuations occur in 2-sector models under plausible configurations regarding all structural parameters—in particular regarding the intensity of income effects. Second, we prove that there even exist some configurations for which local indeterminacy arises under any degree of income effect. More precisely, for any given size of income effect, we show that there is a non-empty range of values for the Frisch elasticity of labor and the elasticity of intertemporal substitution in consumption such that indeterminacy occurs. This contrasts with the results obtained in one-sector models in both Nishimura et al. (2009), in which it is shown that indeterminacy cannot occur under either GHH and KPR preferences, and in Jaimovich (2008) in which local indeterminacy only arises for intermediary income effects.

Should a country invest more in human or physical capital

Should a country invest more in human or physical capital? The present paper addresses this issue, considering the impact of different factor intensities between sectors on both optimal human and physical capital accumulation. Using a two-sector overlapping generations setting with endogenous growth driven by human capital accumulation, we prove that relative factor intensity between sectors drastically shapes the welfare analysis: two laissez-faire economies with the same global capital share may generate physical capital excess or scarcity, with respect to the optimum. The model for the Japanese economy, that experienced a factor intensity reversal after the oil shock, is then calibrated. It is shown that Japan invested relatively too much in human capital before 1975, but has not invested enough since 1990.

A Two-sector Overlapping Generations Model with Endogenous Discounting

In this paper, we consider a two-sector two-periods overlapping generations model with inelastic labor, consumption in both periods of life, endogenous discounting and homothetic preferences. We prove that under the assumption of under-accumulation of capital, an economy with endogenous discounting depending on income is much more likely to experience macroeconomic fluctuations compared to an economy with constant discounting.