School of Business
University of Leicester
Leicester LE1 7RH
Phone: +44 (116) 252 2880
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Precautionary Saving Behaviour under Ambiguity
First Version: 2nd August, 2022.
Abstract: This paper analyses a two-period model in which a consumer faces a future income risk but is uncertain about its probability distribution. We derive three sets of sufficient conditions under which a consumer with generalised recursive smooth ambiguity (GRSA) preferences will save more under ambiguity than in a deterministic environment. Our results show how precautionary saving is jointly determined by attitudes toward atemporal risk, ambiguity and intertemporal substitution. We also find a close connection between risk prudence under non-expected utility and precautionary saving under GRSA preferences.
Source of Economic Growth in Models with Non-Renewable Resources (with Hongsilp Sriket)
Journal of Macroeconomics, vol. 62, June 2022.
Abstract: This paper re-examines the conditions under which endogenous economic growth can emerge in neoclassical models with non-renewable resources. Our analysis is based on a general production function which encompasses the Cobb-Douglas specification. We show that endogenous growth is possible only when the elasticity of substitution between effective labour input and effective resource input is constant and equal to one. If this does not hold (as some empirical studies suggested), then economic growth is solely driven by an exogenous technological factor. We also show that the assumption on this elasticity will affect the model's policy implications in regard to resource taxation.
Diversity and Economic Performance in a Model with Progressive Taxation (with Wei Wang)
Economic Journal, vol. 129, issue 623, p.2949-2977, 2019.
Working paper version
Abstract: Is a more heterogeneous population beneficial or harmful to long-term economic performance? This paper addresses this and other questions in a dynamic general equilibrium model where consumers have different labour productivity and time preference. We show how differences in the cross-sectional distribution of these characteristics can affect the economy via two channels. The first one involves changing the composition of the labour force; and the second one involves changing the cross-sectional distribution of marginal tax rate. We show how these channels are, respectively, determined by the shape of the labour supply function and the curvature of the marginal tax function.
Research Policy and U.S. Economic Growth
First Version: August 14, 2013.
Abstract: This paper examines quantitatively the effects of R&D subsidy and government-financed basic research on U.S. economic growth and consumer welfare. To achieve this, we develop an endogenous growth model which takes into account both public and private research investment, and the differences between basic and non-basic research. A calibrated version of the model is able to replicate some important features of the U.S. economy over the period 1953-2009. Our model suggests that government spending on basic research is an effective policy instrument to promote economic growth. Subsidizing private R&D, on the other hand, has no effect on economic growth.
Concave Consumption Function and Precautionary Wealth Accumulation*
Abstract: This paper examines the theoretical foundations of precautionary saving behavior in a canonical life-cycle model where consumers face uninsurable idiosyncratic labor income risk and borrowing constraints. We begin by characterizing the consumption function of individual consumers. We show that the consumption function is concave when the utility function has strictly positive third derivative and the inverse of absolute prudence is a concave function. These conditions encompass all HARA utility functions with strictly positive third derivative as special cases. We then show that when consumption function is concave, a mean-preserving increase in income risks would encourage wealth accumulation at both the individual and aggregate levels.
* This paper was previously circulated under the title "Concave Consumption Function under Borrowing Constraints."
Standard Risk Aversion and Efficient Risk Sharing
Economics Letters, vol. 173, p.23-26, 2018.
Abstract: This paper analyzes the risk attitude and investment behavior of a group of heterogeneous consumers who face an uninsurable background risk. It is shown that standard risk aversion at the individual level does not imply standard risk aversion at the group level under efficient risk sharing. This points to a potential divergence between individual and collective investment choices in the presence of background risk. We show that if the members' absolute risk tolerance is increasing and satisfies a strong form of concavity, then the group has standard risk aversion.
Technological Advance and the Growth in Health Care Spending
Abstract: Since 1950, the U.S. has experienced a significant expansion in health care spending and longevity. In this paper, we quantify the importance of medical technology improvements and rising incomes in explaining these changes. To achieve this, we develop a dynamic general equilibrium model in which consumers face idiosyncratic uncertainty in health. Both health care spending and life expectancy are endogenously determined. According to our model, medical technology improvements and rising incomes can explain all of the increase in health care spending and more than 60% of the increase in life expectancy at age 25 in the United States between 1950 and 2001.
Asset Bubbles in an Overlapping Generations Model with Endogenous Labor Supply (with Lisi Shi)
Economics Letters, vol. 123 (2), p.164-167, 2014.
Abstract: This short paper examines the effects of asset bubbles in an overlapping generations model with endogenous labor supply. We derive a set of conditions under which asset bubbles will lead to an expansion in steady-state capital, investment, employment and output. We also provide a specific numerical example to illustrate these results.
Time Preference and the Distributions of Wealth and Income
Economic Inquiry, vol. 52 (1), p. 364-381, 2014.
Working paper version
Abstract: This paper examines the connection between time preference heterogeneity and economic inequality in a deterministic environment. Specifically, we extend the standard neoclassical growth model to allow for (i) heterogeneity in consumers' discount rates, (ii) direct preferences for wealth, and (iii) human capital formation. The second feature prevents the wealth distribution from collapsing into a degenerate distribution. The third feature generates a strong positive correlation between earnings and capital income across consumers. A calibrated version of the model is able to generate patterns of wealth and income inequality that are very similar to those observed in the United States.
A Quantitative Analysis of Suburbanization and the Diffusion of the Automobile*
with Karen A. Kopecky
International Economic Review, vol. 51 (4), p. 1003-1037, 2010
Working paper version
Abstract: Suburbanization in the U.S. between 1910 and 1970 was concurrent with the rapid diffusion of the automobile. A circular city model is developed in order to access quantitatively the contribution of automobiles and rising incomes to suburbanization. The model incorporates a number of driving forces of suburbanization and car adoption, including falling automobile prices, rising real incomes, changing costs of traveling by car and with public transportation, and urban population growth. According to the model, 60 percent of postwar (1940-1970) suburbanization can be explained by these factors. Rising real incomes and falling automobile prices are shown to be the key drivers of suburbanization.
*This paper was previously circulated with the title “Suburbanization and the Automobile.”
Finite State Markov-Chain Approximations to Highly Persistent Processes
with Karen A. Kopecky
Review of Economic Dynamics, vol. 13 (3), p. 701-714, 2010.
Abstract: The Rouwenhorst method of approximating stationary AR(1) processes has been overlooked by much of the literature despite having many desirable properties unmatched by other methods. In particular, we prove that it can match the conditional and unconditional mean and variance, and the first-order autocorrelation of any stationary AR(1) process. These properties make the Rouwenhorst method more reliable than others in approximating highly persistent processes and generating accurate model solutions. To illustrate this, we compare the performances of the Rouwenhorst method and four others in solving the stochastic growth model and an income fluctuation problem. We find that (i) the choice of approximation method can have a large impact on the computed model solutions, and (ii) the Rouwenhorst method is more robust than others with respect to variation in the persistence of the process, the number of points used in the discrete approximation and the procedure used to generate model statistics.