"Per capita income in the richest countries of the world exceeds that in the poorest countries by more than a factor of 50. What explains these enormous differences? This paper returns to several old ideas in development economics and proposes that linkages, complementarity, and superstar...

Research and development (Ramp;D) is a key determinant of long run productivity and welfare. A central issue is whether a decentralized economy undertakes too little or too much Ramp;D. We develop an endogenous growth model that incorporates parametrically four important distortions to Ramp;D:...