This paper applies a number of stochastic cost frontier models to a panel data set and compares their ability to distinguish unobserved heterogeneity from inefficiency variation among firms. The main focus is on Greene's 2005 panel data model that incorporates firm-specific effects in a...

The standard economy-wide indices of labour quality (or human capital) largely ignore the role of unobservable worker characteristics. In this article, we develop a methodology for identifying the contributions of both observable and unobservable worker characteristics in the presence of the...