Tom Krebs

Human Capital Risk and Economic Growth

This paper develops a tractable incomplete-markets model of economic growth in which households invest in risk-free physical capital and risky human capital. The paper shows that a reduction in uninsurable idiosyncratic labor income risk decreases physical capital investment, but increases human capital investment, growth, and welfare. A quantitative analysis based on a calibrated version of the model reveals that these effects are substantial and of the same order of magnitude as the effects of distortionary income taxation. The analysis further suggests that government-sponsored severance payments to displaced workers increase growth and welfare even if these payments have to be financed through distortionary income taxation.

Growth and welfare effects of business cycles in economies with idiosyncratic human capital risk

This paper uses a tractable macroeconomic model with idiosyncratic human capital risk and incomplete markets to analyze the growth and welfare effects of business cycles. The analysis is based on the assumption that the elimination of business cycles eliminates the variation in idiosyncratic risk. The paper shows that a reduction in the variation in idiosyncratic risk decreases the ratio of physical to human capital and increases the total investment return and welfare. If the degree of risk aversion is less than or equal to one, then economic growth is enhanced. This paper also provides a quantitative assessment of the macroeconomic effects of business cycles based on a calibrated version of the model. Even for relatively small degrees of risk aversion (around one) the model implies that the elimination of business cycles has substantial effects on investment in physical and human capital, economic growth, and welfare. (Copyright: Elsevier)

Trade Policy, Income Risk, and Welfare

This paper studies empirically the relationship between trade policy and individual income risk faced by workers, and uses the estimates of this empirical analysis to evaluate the welfare effect of trade reform. The analysis proceeds in three steps. First, longitudinal data on workers are used to estimate time-varying individual income risk parameters in various manufacturing sectors. Second, the estimated income risk parameters and data on trade barriers are used to analyze the relationship between trade policy and income risk. Finally, a simple dynamic incomplete-market model is used to assess the corresponding welfare costs. In the implementation of this methodology using Mexican data, we find that trade policy changes have a significant short run effect on income risk. Further, while the tariff level has an insignificant mean effect, it nevertheless changes the degree to which macroeconomic shocks affect income risk.

Welfare Cost of Business Cycles When Markets Are Incomplete

This paper analyzes the welfare costs of business cycles when workers face uninsurable idiosyncratic labor income risk. In accordance with the previous literature, this paper decomposes labor income risk into an aggregate and an idiosyncratic component, but in contrast to the previous literature, this paper allows for multiple sources of idiosyncratic labor income risk. Using the multi-dimensional approach to idiosyncratic risk, this paper provides a general characterization of the welfare cost of business cycles when preferences and the (marginal) process of individual labor income in the economy with business cycles are given. The general analysis shows that the introduction of multiple sources of idiosyncratic risk never decreases the welfare cost of business cycles, and strictly increases it if there are cyclical fluctuations across the different sources of risk. Finally, this paper also provides a quantitative analysis of multi-dimensional labor income risk based on a version of the model that is calibrated to match U.S. labor market data. The quantitative analysis suggests that realistic variations across two particular dimensions of idiosyncratic labor income risk increase the welfare cost of business cycles by a substantial amount.

Non-Existence of Recursive Equilibria on Compact State Spaces When Markets are Incomplete

Abstract This paper analyzes one-good exchange economies with two infinitely lived agents and incomplete markets. It is shown that there are no recursive (Markov) equilibria for which borrowing (debt) constraints never bind if the state space of exogenous and endogenous variables is a compact subset of R n . Moreover, for large enough (but finite) borrowing limits, no recursive equilibrium with compact state space exists. These non-existence results hold for any economy satisfying the following standard assumptions: preferences are additively separable across time and states; the one-period utility function is time- and state-independent and unbounded from below; endowments are bounded and follow a Markov chain with stationary transition matrix; there is some idiosyncratic risk and no aggregate risk.

Testable implications of consumption-based asset pricing models with incomplete markets☆

Abstract This paper studies the testable implications of consumption-based asset pricing models with incomplete markets when idiosyncratic income shocks are permanent. It is shown that the theory places no testable restrictions (beyond absence of arbitrage) on either the macroeconomic data or the first N moments of the cross-sectional distribution of consumption growth even if the one-period utility function (degree of risk aversion) is known. More precisely, this paper shows that any “observed” joint process of aggregate consumption, arbitrage-free asset returns, and N moments of the cross-sectional distribution of consumption growth is an equilibrium outcome for some pure discount factor and some process of individual income. The proof is based on the construction of a personal-disaster process (process of extreme idiosyncratic events) which allows for arbitrary variations in idiosyncratic risk without affecting the first N moments of the cross-sectional distribution of consumption growth.

Asset returns in an endogenous growth model with incomplete markets

An air bag has an air bag main body and a sheet. The air bag main body is formed into such a sac like shape as having a circumferential wall portion that extends in a sleeve-like form from a peripheral edge of an opening and a bottom wall portion that closes the circumferential wall portion. The sheet is arranged so as to extend from the peripheral edge of the opening to the bottom wall portion via the circumferential wall portion in such a manner that the air bag main body is split into two parts, and the sheet has a communicating hole. The sheet in sewn only to a portion of the peripheral edge of the opening in the circumferential wall portion and to a portion of the bottom wall portion.

Fundamentals, information, and international capital flows: A welfare analysis

Abstract In the recent discussion surrounding the design of a new international financial architecture, enhancing transparency has widely been proposed as a policy essential for increasing the efficiency of international capital markets. This paper uses a simple two-country (two-agent) general equilibrium model with incomplete markets and production to explore the welfare consequences of an increase in public information about country-specific fundamentals (increase in transparency). An improvement in the quality of information has two effects on the ex ante welfare of individual countries: A direct effect that increases the efficiency of global capital allocation and welfare, and an indirect general equilibrium effect that increases asset price volatility and may decrease welfare. When the degree of risk-aversion is low, at least one country will gain from an increase in information quality. If the degree of risk-aversion is high, then there are robust examples of economies for which an increase in information hurts all countries. The paper also discusses how certain institutional arrangements (international derivative markets, international agency) could ensure that all countries gain from better information by providing insurance against information-induced asset price risk.

A Macroeconomic Model for the Evaluation of Labor Market Reforms

We develop a tractable macroeconomic model with employment risk and labor market search in order evaluate the effects of labor market reform on unemployment, growth, and welfare. The model has a large number of risk-averse households who can invest in risk-free physical capital and risky human capital. Unemployed households receive unemployment benefits and decide how much search effort to exert. We present a theoretical characterization result that facilitates the computation of equilibria substantially. We calibrate the model to German data and use the calibrated model economy to simulate the macroeconomic effects of the German labor market reforms of 2005 and 2006 (Hartz Reforms). We find that the 2005-reform had large employment effects: the equilibrium unemployment rate has been reduced by approximately 1.1 percentage points from 7.5 to 6.4 percent. Moreover, the drop in unemployment has led to substantial output gains. Finally, employed and short-term unemployed households experienced significant welfare gains, whereas the long-term unemployed have lost in welfare terms. The effects of the 2006-reform are qualitatively similar, but quantitatively much smaller. We also show that the social welfare maximizing replacement rate is lower than the current (post-reform) replacement rate in Germany. However, implementing the optimal unemployment benefit system generates only small welfare gains.

Income Mobility and Welfare

This paper develops a framework for the quantitative analysis of individual income dynamics, mobility and welfare. Individual income is assumed to follow a stochastic process with two (unobserved) components, an i.i.d. component representing measurement error or transitory income shocks and an AR(1) component representing persistent changes in income. We use a tractable consumption-saving model with labor income risk and incomplete markets to relate income dynamics to consumption and welfare, and derive analytical expressions for income mobility and welfare as a function of the various parameters of the underlying income process. The empirical application of our framework using data on individual incomes from Mexico provides striking results. Much of measured income mobility is driven by measurement error or transitory income shocks and therefore (almost) welfare-neutral. A smaller part of measured income mobility is due to either welfare-reducing income risk or welfare-enhancing catching-up of low-income individuals with high-income individuals, both of which have economically significant effects on social welfare. Decomposing mobility into its fundamental components is thus seen to be crucial from the standpoint of welfare evaluation.