In this survey, I discuss four sources of growth of knowledge: research, schooling, learning by doing, and training. In trying to disentangle what is important, I emphasize the following facts: (1) even the most advanced countries spend far more on adoption of existing technologies than on...

We model research as a signal on an unknown parameter of a technology. We distinguish applied from basic research and show that firms in the same industry can optimally choose different research portfolios, and that basic research can seem to have a higher rate of return than applied research,...

In many industries firms can learn about new technologies from other adopters; mandatory disclosure regulations represent an understudied channel for this type of social learning. We study an environmentally-focused law in the shale gas industry to examine firms' claims that disclosure...

Relationship-specific learning is consequential because it implies that relationship stability is important to productivity. When two firms accumulate experience working together, relationship-specific intellectual capital is created that cannot be appropriated to pairings with other firms. If...

We conduct a randomized experiment that generates exogenous variation in the access to foreign markets for rug producers in Egypt. Combined with detailed survey data, we causally identify the impact of exporting on firm performance. Treatment firms report 16-26 percent higher profits and exhibit...

We develop a model of firm learning in volatile markets with noisy signals and test its predictions using historical data from the Ifo Institute's Business Climate Survey. We find that firms' forecasts improve as they age. We also exploit German Reunification as a natural experiment where firms...

Since independence a quiet revolution has taken place in maize production in the Sahel with Mali increasing production more than ten-fold and yields going up ~2% a year. This research work uses farm level panel data from southern Mali's maize growing regions to demonstrate this success in...

"We prove that the change in welfare of a representative consumer is summarized by the current and expected future values of the standard Solow productivity residual. The equivalence holds if the representative household maximizes utility while taking prices parametrically. This result justifies...