This paper argues that the typical household’s saving is better described by a “bufferstock” version than by the traditional version of the Life Cycle/Permanent Income Hypothesis (LC/PIH) model. Buffer-stock behavior emerges if consumers with important income uncertainty are sufficiently impatient. In the traditional model, consumption growth is determined solely by tastes; in contrast, buffer-stock consumers set average consumption growth equal to average labor income growth, regardless of tastes. The model can explain three empirical puzzles: the “consumption/income parallel ” of Carroll and Summers [1991]; the “consumption/income divergence ” first documented in the 1930's; and the temporal stability of the household age/wealth profile despite the unpredictability of idiosyncratic wealth changes.

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This paper develops new economic models to synthesize and interpret the empirical literature on human skill formation. It presents simple formal economic models of child development that capture the essence of recent findings from the empirical literature. The goal of this essay is to provide a theoretical framework for interpreting the evidence from a vast empirical literature, for guiding the next generation of empirical studies, and for formulating policy. Central to our analysis is the concept that childhood has more than one stage, and that policies need to be tailored to each one. We formalize the concepts of self productivity and complementarity of human capital investments and use them to explain the evidence on skill formation. Together, they explain why skill begets skill through a skill multiplier process. Skill formation is a lifecycle process. It starts in the womb and goes on throughout most of the adult life. Families play a

This paper studies stationary equilibria of a production economy with a continuum of heterogeneous consumers subject to borrowing constraints and individual Markov endowment shocks. The existence of a stationary equilibrium is established. The equilibrium interest rate is less than the rate of time preference of the most patient consumer provided a constraint that restricts the borrowing limit is satisfied. Properties of stationary equilibria including wealth distribution, precautionary savings and comparative statics are analyzed. Key words: stationary equilibria, heterogeneity, precautionary savings, lattice theory, aggregation, comparative statics, borrowing constraint, wealth distribution, law of large numbers

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Macroeconomics is evolving from the study of aggregate dynamics to the study of the dynamics of the entire equilibrium distribution of allocations across individual economic actors. This article reviews the quantitative macroeconomic literature that focuses on household heterogeneity, with a special emphasis on the “standard” incomplete markets model. We organize the vast literature according to three themes that are central to understanding how inequality matters for macroeconomics. First, what are the most important sources of individual risk and cross-sectional heterogeneity? Second, what are individuals ’ key channels of insurance? Third, how does idiosyncratic risk interact with aggregate risk?

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This paper estimates a structural model of optimal life-cycle consumption expenditures in the presence of realistic labor income uncertainty. We employ synthetic cohort techniques and Consumer Expenditure Survey data to construct average age-profiles of consumption and income over the working lives of typical households across different education and occupation groups. The model fits the profiles quite well. In addition to providing reasonable estimates of the discount rate and risk aversion, we find that consumer behavior changes strikingly over the life cycle. Young consumers behave as buffer-stock agents. Around age 40, the typical household starts accumulating liquid assets for retirement and its behavior mimics more closely that of a certainty equivalent consumer. Our methodology provides a natural decomposition of saving and wealth into its precautionary and life-cycle components.

We tackle the problem of the optimal quantity of money in model in the spirit of Friedman’s (1969) seminal work. Provided the seignorage proceedings are distributed uniformly, we prove that the Friedman rule fails to maximize welfare, is dynamically inconsistent, and strains the capital formation. 1 1

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