Research Database

Intellectual property protection involves a trade-off between the undesirability of monopoly and the desirable encouragement of creation and innovation. As the scale of the market increases, due either to economic and population growth or to the expansion of trade through treaties such as the World Trade Organization, this trade-off changes. We show that, generally speaking, the socially optimal amount of protection decreases as the scale of the market increases. We also provide simple empirical estimates of how much it should decrease.

Innovation and the adoption of new ideas are fundamental to economic progress. Here we examine the underlying economics of the market for ideas. From a positive perspective, we examine how such markets function with and without government intervention. From a normative perspective, we examine the pitfalls of existing institutions, and how they might be improved. We highlight recent research by ourselves and others challenging the notion that government awards of monopoly through patents and copyright are “the way” to provide appropriate incentives for innovation.

We propose a notion of smoothness of nonexpected utility functions, which extends the variational analysis of nonexpected utility functions to more general settings. In particular, our theory applies to state dependent utilities, as well as the multiple prior expected utility model, both of which are not possible in previous literatures. Other nonexpected utility models are shown to satisfy smoothness under more general conditions than the Fréchet and Gateaux differentiability used in the literature. We give more general characterizations of monotonicity and risk aversion without assuming state independence of utility function.

This paper studies the stability of a stochastic optimal growth economy introduced by Brock and Mirman [J. Econ. Theory 4 (1972)] by utilizing stochastic monotonicity in a dynamic system. The construction of two boundary distributions leads to a new method of studying systems with non-compact state space. The paper shows the existence of a unique invariant distribution. It also shows the equivalence between the stability and the uniqueness of the invariant distribution in this dynamic system.

This paper describes a newly constructed data set of all U.S. state banks from 1782 to 1861. It contains the names and locations of all banks and branches that went into business and an estimate of when each operated. The compilation is based on reported balance sheets, listings in banknote reporters, and secondary sources. Based on these data, the paper presents a count of the number of banks and branches in business by state. I argue that my series are superior to previously existing ones for reasons of consistency, accuracy, and timing. The paper contains examples to support this argument.

Time-varying risk is the primary force driving nominal interest rate differentials on currency-denominated bonds. This finding is an immediate implication of the fact that exchange rates are roughly random walks. We show that a general equilibrium monetary model with an endogenous source of risk variation—a variable degree of asset market segmentation—can produce key features of actual interest rates and exchange rates. The endogenous segmentation arises from a fixed cost for agents to exchange money for assets. As inflation varies, the benefit of asset market participation varies, and that changes the fraction of agents participating. These effects lead the risk premium to vary systematically with the level of inflation. Our model produces variation in the risk premium even though the fundamental shocks have constant conditional variances.

In this paper I develop continuous-time methods for solving dynamic principal-agent problems in which the agent’s privately observed productivity shocks are persistent over time. I characterize the optimal contract as the solution to a system of ordinary differential equations, and show that, under this contract, the agent’s utility converges to its lower bound—immiseration occurs. I also show that, unlike in environments with i.i.d. shocks, the principal would like to renegotiate with the agent when the agent’s productivity is low—it is not renegotiation-proof. I apply the theoretical methods I have developed and numerically solve this (Mirrleesian) dynamic taxation model. I find that it is optimal to allow a wedge between the marginal rate of transformation and individuals’ marginal rate of substitution between consumption and leisure. This wedge is significantly higher than what is found in the i.i.d. case. Thus, using the i.i.d. assumption is not a good approximation quantitatively when there is persistence in productivity shocks.

This paper studies a quantitative dynamic general equilibrium life-cycle model where parents and their children are linked by bequests, both voluntary and accidental, and by the transmission of earnings ability. This model is able to match very well the empirical observation that households with similar lifetime incomes hold very different amounts of wealth at retirement. Income heterogeneity and borrowing constraints are essential in generating the variation in retirement wealth among low lifetime income households, while the existence of intergenerational links is crucial in explaining the heterogeneity in retirement wealth among high lifetime income households.

In this article, I examine the current state of knowledge about optimal monetary policy. I distinguish between two literatures, basic and applied. The basic literature is explicit about the frictions that generate a positive value for money and make it socially beneficial. The applied literature is not. I describe the recent lessons about monetary policy that we have learned from each literature and discuss how the two distinct approaches may be usefully combined.

A Welfare-to-Work (WTW) program is a mix of government expenditures on “passive” (unemployment insurance, social assistance) and “active” (job search monitoring, training, wage taxes/subsidies) labor market policies targeted to the unemployed. This paper provides a dynamic principal-agent framework suitable for analyzing the optimal sequence and duration of the different WTW policies, and the dynamic pattern of payments along the unemployment spell and of taxes/subsidies upon re-employment. First, we show that the optimal program endogenously generates an absorbing policy of last resort (that we call “social assistance”) characterized by a constant lifetime payment and no active participation by the agent. Second, human capital depreciation is a necessary condition for policy transitions to be part of an optimal WTW program. Whenever training is not optimally provided, we show that the typical sequence of policies is quite simple: the program starts with standard unemployment insurance, then switches into monitored search and, finally, into social assistance. Only the presence of an optimal training activity may generate richer transition patterns. Third, the optimal benefits are generally decreasing or constant during unemployment, but they must increase after a successful spell of training. In a calibration exercise based on the U.S. labor market and on the evidence from several evaluation studies, we use our model to analyze quantitatively the features of the optimal WTW program for the U.S. economy. With respect to the existing U.S. system, the optimal WTW scheme delivers sizeable welfare gains, by providing more insurance to skilled workers and more incentives to unskilled workers.