This paper studies the efficiency with which physical capital can be reallocated across sectors. It presents a model of a firm selling specialized capital in a thin resale market. The model predicts that the selling price depends not only on the sectoral specificity of capital, but also on the...

This paper develops a simple approximation method for computing equilibrium portfolios in dynamic general equilibrium open economy macro models. The method is widely applicable, simple to implement, and gives analytical solutions for equilibrium portfolio positions in any combination or types of...

The existing economics literature on international trade agreements focuses on tariff agreements covering trade in goods, and offers an explanation for core features of the GATT. Tariffs play almost no role in services markets, however, and the existing models cannot account for the dramatically...

We develop a model of repeated product improvements in a continuum of sectors. Each product follows a stochastic progression up a quality ladder. Progress is not uniform across sectors, so an equilibrium distribution of qualities evolves over time. But the rate of aggregate growth is constant....

We analyze entry, pricing and product design in a model with differentiated products. Under plausible conditions, entry into an initially monopolized market leads to higher prices for some, possibly all, consumers. Entry can induce a misallocation of goods to consumers, segment the market in a...

Product redesigns happen across virtually all types of products. While there is substantial evidence that new varieties of goods increase welfare, there is little evidence on the effect of product redesigns. We develop a model of redesign and exit decisions in a dynamic oligopoly model (a la...

Cigarette smoking leads to large healthcare and morbidity costs, and mortality losses, and smoking cessation plays a key role in reducing health risk and economic costs. While medical evidence suggests that some smokers are more likely to respond to medication treatment than others depending on...

This paper derives optimal income tax and human capital policies in a dynamic life cycle model of labor supply and risky human capital formation. The wage is a function of both stochastic, persistent, and exogenous "ability'' and endogenous human capital. Human capital is acquired throughout...

This paper extends the standard life cycle model to a world in which there are also capitalists. We obtain simple formulae describing the equilibrium fraction of wealth held by life-cycle savers. Using these formulae, we ascertain the effects of tax policy or changes in the parameters of the...