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...

Local opinion leaders may play a key role in easing information frictions associated with technology adoption. This paper analyzes the influence of physician investigators who lead clinical trials for new cancer drugs. By comparing diffusion patterns across 21 new cancer drugs, we separate...

In this paper we analyze the evidence from a large number of studies on three specific questions pertaining to R&D investment: (1) Are there diminishing returns to inventive activities? (2) What is the relationship between R&D and productivity and what are the magnitudes of the returns to a...

Investment in research and development (R&D) affects a country's total factor productivity. Recently new theories of economic growth have emphasized this link and have also identified a number of channels through which a country's R&D affects total factor productivity of its trade partners....

Are scientific knowledge flows embodied in individuals, or "in the air"? To answer this question, we measure the effect of labor mobility in a sample of 9,483 elite academic life scientists on the citation trajectories associated with individual articles (resp. patents) published (resp. granted)...

Much recent work has suggested that endogenous technological change tends to reinforce the position of the leading nations. Yet from time to time this leadership role shifts. We suggest a mechanism that explains this pattern of -leapfrogging- as a response to occasional major changes in...

I discuss the concept and empirical importance of international technology diffusion from the point of view of recent work on endogenous technological change. In this literature, technology is viewed as technological knowledge. I first review the major concepts, and how international technology...

This paper presents a new data set on the diffusion of about 115 technologies in over 150 countries over the last 200 years. We use this comprehensive data set to uncover general patterns of technology diffusion. Our main 5 findings are as follows: (i) Once the intensive margin is measured,...

We develop and estimate a model where technology diffusion depends on the level of productivity embodied in capital and where this is, in turn, determined by two key mechanisms: the rate at which the quality embodied in new technology vintages increases (embodiment) and the gains from varieties...

The importance of new technologies derives from the fact that they spread across many different users and uses, as well as different geographic regions. The diffusion of technological improvements, across producers within a country and across international borders, is critical for long run...