We construct a model of firm dynamics with heterogeneous productivity and distortions. The productivity distribution evolves endogenously as the result of the decisions of firms seeking to upgrade their productivity over time. Firms can adopt two strategies toward that end: imitation and...

We explore the determinants of research specialization across countries and its consequences for relative wages. Using a dynamic Ricardian model we examine the effects of faster international technology diffusion and lower trade barriers on the incentive to innovate. In the absence of any...

In many growth models, economic growth arises from people creating ideas, and the long-run growth rate is the product of two terms: the effective number of researchers and their research productivity. We present a wide range of evidence from various industries, products, and firms showing that...

Researchers have long hypothesized that spillovers from government, university, and private company R&D contribute to economic growth, but these contributions may be difficult to measure when they take a non-pecuniary form. The growth of networking devices and the Internet in the 1990s and 2000s...

This paper examines the role of agricultural diversity in the process of development. Using data from U.S. counties and exploiting climate-induced variation in agricultural production patterns, I show that mid-19th century agricultural diversity had positive long-run effects on population...

This paper explores the implications of a simple model of learning and innovation by firms. In this model R&D spillovers are partly determined by firms, rather than by the given economic environment. According to this approach the full effect of spillovers on research productivity of firms...

Is public R&D spending complementary and thus "additional" to private R&D spending, or does it substitute for and tend to "crowd out" private R&D? Conflicting answers are given to this question. We survey the body of available economectric evidence accumulated over the past 35 years. A framework...

This paper surveys the major changes in patent policy and practice that have occurred in the last two decades in the U.S., and reviews the existing analyses by economists that attempt to measure the impacts these changes have had on the processes of technological change. It also reviews the...

When investing in research and development (R&D), institutions must decide whether to take a top-down approach -- soliciting a particular technology -- or a bottom-up approach in which innovators suggest ideas. This paper examines a reform to the U.S. Air Force Small Business Innovation Research...