This paper uses wavelets to decompose each stock's trading-volume variance into frequency-specific components. We find that stocks dominated by short-run fluctuations in trading volume have abnormal returns that are 1% per month higher than otherwise similar stocks where short-run fluctuations...

I generalize a benchmark model of directed technical change to allow innovations and factors of production (here energy resources) to be substitutes or complements. I show that a dominant sector is forever locked-in under substitutability but researchers' market incentives can drive a transition...

We study how opening to trade affects economic growth in a model where heterogeneous firms can adopt new technologies already in use by other firms in their home country. We characterize the growth rate using a summary statistic of the profit distribution—the mean-min ratio. Opening to trade...

We develop a microeconomic model of endogenous growth where clean and dirty technologies compete in production and innovation—in the sense that research can be directed to either clean or dirty technologies. If dirty technologies are more advanced to start with, the potential transition to...

This paper develops and estimates a dynamic structural model of demand for a multi-attribute product. The demand side equilibrium supports a product spectrum, the characteristics of which evolve over time in response to supply innovations induced by the composition and extent of aggregate...

We consider trade between two countries of unequal size, where the creation of new intermediate inputs occurs in both. We assume that the knowledge gained from R&D in one country does not spillover to the other. Under autarky, the larger country would have a higher rate of product creation. When...

The contribution made by innovation and new technologies to economic growth and welfare is largely determined by the rate and manner by which innovations diffuse throughout the relevant population, but this topic has been a somewhat neglected one in the economics of innovation. This chapter,...

Technological diffusion implies a form of 'conditional convergence' as lagging countries catch up with technological leaders. We find strong evidence of technological diffusion but not full convergence; differences in total factor productivity (TFP) persist even in the long run due to differences...

The usual explanation for why the producers of a given product use different technologies involves "vintage-capital": A firm understands the frontier technology, but can still prefer an older, less efficient technology in which it has made specific physical and human capital investments. This...

We examine the role of network effects in the demand for pharmaceuticals at both the brand level and for a therapeutic class of drugs. These effects emerge when use of a drug by others conveys information about its efficacy and safety to patients and physicians. This can lead to herd behavior...