Revisiting the world technology frontier: a directional distance function approach

This paper revisits the finding of Caselli and Coleman (Amer Econ Rev 96:499–522, 2006) that poor countries are relatively more efficient in using unskilled labor whereas rich countries are more efficient in using skilled labor. The analysis is based on an approach using directional distance functions from nonparametric efficiency analysis which relies on very mild assumptions. We find that the central result of Caselli and Coleman is robust to using the nonparametric approach. The result is, however, sensitive to alternative definitions of skilled and unskilled labor, data sources and variations of the measurement approach.