摘要：In this paper, we attempt to estimate pure national (technical) efficiency for 19 SSAcountries over the 1960-2010 periods. In doing this, we compare conventional stochasticfrontier models for panel data with a number of recently developed models which seek tocontrol for unobserved heterogeneity in the inefficiency component. We find that the ‘true’random effects model that treats unobserved heterogeneity in our national dataset generatesmore reasonable efficiency estimates. Moreover the results confirm that most SSA countriesoperate far from the efficient frontier.
