The one sector neoclassical model with exogenous technological progress is still the fundamental workhorse of growth theory. It rests on two powerful hypotheses: Aggregate technical progress exists, proceeding at an approximately constant growth rate; Technical change is neutral. These assumptions have important implications for the traditional specification of the aggregate production function, the way in which technical progress is introduced into growth models and more generally for how economists think about the growth process. This volume applies statistical techniques of data analysis...