We develop a framework for studying trade in vertically and horizontally differentiated products. In our model, consumers with heterogeneous incomes and tastes purchase a homogeneous good as well as making a discrete choice of quality and variety of a differentiated product. The distribution of...

We develop a two-country model of endogenous innovation and imitation in order to study the interactions between these two processes. Firms in the North race to bring out the next generation of a set of technology-intensive products. Each product potentially can be improved a countably infinite...

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....

This paper presents stochastic simulation results pertaining to the performance of nominal income targeting, here represented as a monetary policy rule that sets quarterly values of an interest rate instrument in response to deviations on existing studies of nominal income growth from a...

This paper explores several issues concerning a possible zero lower bound (ZLB) including its theoretical rationale; the magnitude of effects of low sustained inflation on real interest rates; the validity of analyzing monetary policy in models with no monetary variables; and the dynamic...

This paper surveys the field of asset pricing. The emphasis is on the interplay between theory and empirical work, and on the tradeoff between risk and return. Modern research seeks to understand the behavior of the stochastic discount factor (SDF) that prices all assets in the economy. The...

This paper argues that, in studying the monetary policy transmission process, more emphasis should be given to the systematic portion of policy behavior and correspondingly less to random shocks basically because shocks account for a very small fraction of policy-instrument variability. Analysis...

The poor performance of consumption-based asset pricing models relative to traditional portfolio-based asset pricing models is one of the great disappointments of the empirical asset pricing literature. We show that the external habit-formation model economy of Campbell and Cochrane (1999) can...

This paper studies three different measures of monthly stock market volatility: the time-series volatility of daily market returns within the month; the cross-sectional volatility or 'dispersion' of daily returns on industry portfolios, relative to the market, within the month; and the...

If household portfolios are constrained by borrowing and short-sales restrictions asset markets, then alternative retirement savings systems may affect household welfare by relaxing these constraints. This paper uses a calibrated partial-equilibrium model of optimal life-cycle portfolio choice...