"The authors follow the Hellerstein, Neumark, and Troske (1999) framework to estimate marginal productivity … differentials and compare them with estimated relative wages. The analysis provides evidence on productivity and nonproductivity … training on wages and productivity differentials. Higher education yields higher productivity. However, highly educated workers …

"Empirical explorations of the growth and productivity impacts of infrastructure have been characterized by ambiguous … indirect) channels of influence between infrastructure and productivity improvements. The authors explore these possibilities … alternative measures of productivity, the prevalence of ambiguous (countervailing signs) results, with little systematic pattern …