Many widely used economic models implicitly assume that income shares should be identical across time and space. Although time-series data from industrial countries appear consistent with this notion, cross-section data generally appear to contradict the assumption. A commonly used calculation...

Standard measures of productivity display enormous dispersion across farms in Africa. Crop yields and input intensities appear to vary greatly, seemingly in conflict with a model of efficient allocation across farms. In this paper, we present a theoretical framework for distinguishing between...

We examine the economic impact of high-yielding crop varieties (HYVs) in developing countries 1960-2000. We use time variation in the development and diffusion of HYVs of 10 major crops, spatial variation in agro-climatically suitability for growing them, and a differences-in-differences...