This paper introduces endogenous and directed technical change in a growth model with environmental constraints. A unique final good is produced by combining inputs from two sectors. One of these sectors uses "dirty" machines and thus creates environmental degradation. Research can be directed...

We analyse an economy where managers engage both in the adoption of technologies from the world frontier and in innovation activities. The selection of high-skill managers is more important for innovation activities. As the economy approaches the technology frontier, selection becomes more...

This paper studies the role of intrinsic motivation, reputation and reciprocity in driving open source software innovation. We exploit the observed pattern of contributions - the 'revealed preference' of developers - to infer the underlying incentives. Using detailed information on code...

How does firm entry affect innovation incentives and productivity growth in incumbent firms? Micro-data suggests that there is heterogeneity across industries - incumbents in technologically advanced industries react positively to entry, but not in laggard industries. To explain this pattern, we...