Time-varying volatility, precautionary saving and monetary policy

2011

This paper analyses the conduct of monetary policy in an environment where households’ desire to amass precautionary savings is influenced by fluctuations in the volatilities of disturbances that hit the economy. It uses a simple New Keynesian model with external habit formation that is augmented with demand and supply disturbances whose volatilities vary over time. If volatility fluctuations are ignored by policy, interest rates are set at a suboptimal level. The extent of ‘policy bias’ is relatively small but of greater importance the higher the degree of habit formation. The reason is that habit-forming preferences raise risk aversion, increasing the importance of the precautionary savings channel through which volatility fluctuations impact upon inflation and output.

2012

We study the effects of permanent and temporary income shocks on precautionary saving and investment in a "store-or-sow" model of growth. High volatility of permanent shocks results in high precautionary saving in the safe asset and low investment, or a "volatility trap." Namely, big savers invest relatively little. In contrast, low volatility of permanent shocks leads to low precautionary saving and high or low investment, depending on the volatility of temporary shocks. Empirical evidence shows a nonlinear relationship between investment and saving and that investment is a hump-shaped function of the volatility of permanent shocks, as predicted by the model. JEL Classification Numbers: E21, E22, D91, O40

Journal of Monetary Economics, 2008

This paper examines how stochastic changes in risk a¤ect the demand for saving. We consider two models of savings demand: one in which future labor income is risky and one in which the return on savings is risky. In each model, we examine the e¤ects of an N th-degree stochastic change in the risk. For each case, we establish necessary and su¢ cient conditions on preferences that will guarantee that the individual increases his or her level of savings. We show how in the case of only labor income risk, any changes in savings are purely due to precautionary savings motives. For the case where the return on savings is risky, we show how both a precautionary e¤ect and a substitution e¤ect need to be analyzed.

Journal of Monetary Economics, 2004

We study the implications for optimal monetary policy of introducing habit formation in consumption into a general equilibrium model with sticky prices. Habit formation affects the model's endogenous dynamics through its effects on both aggregate demand and households’ supply of output. We show that the objective of monetary policy consistent with welfare maximization includes output stabilization, as well as inflation and output gap stabilization. We find that the variance of output increases under optimal policy, even though it acquires a higher implicit weight in the welfare function. We also find that a simple interest rate rule nearly achieves the welfare-optimal allocation, regardless of the degree of habit formation. In this rule, the optimal responses to inflation and the lagged interest rate are both declining in the size of the habit, although super-inertial policies remain optimal.

Journal of Monetary Economics, 2005

2009

2000

Abstract This paper explores the implications of precautionary saving and life cycle behavior for aggregate fluctuations and individual dynamics. Existing heterogenous agent models of the business cycle, with labor income uncertainty and incomplete markets, yield aggregate quantitative predictions that are almost indistinguishable from their representative agent counterpart. This quasi aggregation theorem arises when idiosyncratic shocks are largely transitory.

Journal of Money, Credit and Banking, 2009

This paper examines how aversion to risk and aversion to intertemporal substitution determine the strength of the precautionary saving motive in a two-period model with Selden/Kreps-Porteus preferences. For small risks, we derive a measure of the strength of the precautionary saving motive which generalizes the concept of "prudence" introduced by Kimball (1990b). For large risks, we show that decreasing absolute risk aversion guarantees that the precautionary saving motive is stronger than risk aversion, regardless of the elasticity of intertemporal substitution. Holding risk preferences fixed, the extent to which the precautionary saving motive is stronger than risk aversion increases with the elasticity of intertemporal substitution. We derive sufficient conditions for a change in risk preferences alone to increase the strength of the precautionary saving motive and for the strength of the precautionary saving motive to decline with wealth. Within the class of constant elasticity of intertemporal substitution, constant-relative risk aversion utility functions, these conditions are also necessary.

Money Macro and Finance Research Group Conference 2006, 2007

This paper develops and estimates a simple New Keynesian Dynamic Stochastic General Equilibrium (DSGE) model with rule-of-thumb consumers and external habits. Our theoretical model has a closed-form solution which allows the analytical derivation of its dynamical and stability properties. These properties are analyzed and discussed in the light of their implications for the efficacy and the calibration of the conduct of the monetary policy. The model is then evaluated empirically, employing numerical simulations based on Monte Carlo Bayesian estimates of the structural parameters and impulse response analyses based on weakly identified SVECMs. The estimates are repeated for each of the G7 national economies. Providing single country estimates and simulations, we derive some indications on the relative efficacy of monetary policy and of its potential asymmetric effects resulting from the heterogeneity of the estimated models.

2002

We study the role of habit formation in shaping the amount of precautionary savings and the wealth distribution in heterogeneous agents model economies with idiosyncratic uncertainty. We adjust preferences to equate the Intertemporal Elasticity of Substitution in all model economies. We find that habit formation brings a hefty increase in precautionary savings and very mild reductions in the coefficient of variation and in the Gini index of wealth. These findings hold for both persistent and non persistent habits, with the effects of the former being much larger.