Moritz Kuhn

Labour Market Institutions and Worker Flows: Comparing Germany and the US

We compare labour market flows in the US and Germany between 1980 and 2004. In Germany, average worker flows in and out of unemployment are substantially lower; outflows are equally volatile in both countries; inflows are about twice as volatile in Germany and contribute more to the unemployment rate volatility. We explore four candidates for these differences: unemployment benefits; union bargaining power; employment protection and the efficiency of matching unemployed workers to open positions. We find that a lower matching efficiency in Germany can explain the bulk of the cross‐country differences. It amplifies the business cycle and adds persistence.

The Era of the U.S.-Europe Labor Market Divide: What Can We Learn?

Comparing labor markets in the United States and Germany as Europe’s largest economy over the period from 1980−2004 uncovers three stylized differences: (1) Germany’s mean transition rates from unemployment to employment (UE) were lower by a factor of 5 and transition rates from employment to unemployment (EU) were lower by a factor of 4. (2) The volatility of the UE rate was equal in both countries, but the EU rate was 2.3 times more volatile in Germany. (3) In Germany EU flows contributed 60−70% to unemployment volatility, whereas in the U.S. they contributed only 30−40%. Using a search and matching model we show theoretically that the joint analysis of first and second moments offers general identification restrictions on the underlying causes for these differences. We find that a lower efficiency in the matching process can consistently explain the facts while alternative explanations such as employment protection, the benefit system, union power, or rigid earnings can not. We document that a lower matching efficiency due to lower occupational and regional mobility in Germany finds strong support in the data. Finally, we show that the highlighted matching friction leads in the model calibrated to the German economy to a substantial amplification and propagation of shocks.

Recursive Equilibria in an Aiyagari‐Style Economy with Permanent Income Shocks

We prove existence of a recursive competitive equilibrium (RCE) for an Aiyagari‐style economy with permanent income shocks and derive important economic implications. We show that there exist equilibria where borrowing constraints are never binding and establish a nontrivial lower bound on the equilibrium interest rate. These results imply distinct consumption dynamics compared to existing studies. We present a new approach to solve the agents problem that uses lattices of consumption functions to deal with permanent income shocks and an unbounded utility function. The approach provides a theoretical foundation for convergence of the time iteration algorithm widely used in applied work.

Insurance in Human Capital Models with Limited Enforcement

This paper develops a tractable human capital model with limited enforceability of contracts. The model economy is populated by a large number of long-lived, risk-averse households with homothetic preferences who can invest in risk-free physical capital and risky human capital. Households have access to a complete set of credit and insurance contracts, but their ability to use the available financial instruments is limited by the possibility of default (limited contract enforcement). We provide a convenient equilibrium characterization that facilitates the computation of recursive equilibria substantially. We use a calibrated version of the model with stochastically aging households divided into 9 age groups. Younger households have higher expected human capital returns than older households. According to the baseline calibration, for young households less than half of human capital risk is insured and the welfare losses due to the lack of insurance range from 3 percent of lifetime consumption (age 40) to 7 percent of lifetime consumption (age 23). Realistic variations in the model parameters have non-negligible effects on equilibrium insurance and welfare, but the result that young households are severely underinsured is robust to such variations.

Optimal Capital Taxation for Time-Nonseparable Preferences

This paper studies the effect of habit formation on optimal capital taxes in a dynamic Mirrleesian model. We make three distinct contributions. First, we decompose intertemporal wedges (implicit capital taxes) for general time-nonseparable preferences into a wealth effect, a complementarity effect, and a future incentive effect. Second, we provide conditions under which intertemporal wedges are positive. Third, we derive a recursive formulation of constrained efficient allocations and evaluate the quantitative impact of habit formation. In a model parameterized to the U.S. economy, habit formation reduces average intertemporal wedges by about 40 percent compared to the time-separable case. Moreover, intertemporal wedges are close to zero for the largest part of the working life.