A Monte Carlo evaluation of the efficiency of the PCSE estimator

Panel data characterized by groupwise heteroscedasticity, cross-sectional correlation, and AR(1) serial correlation pose problems for econometric analyses. It is well known that the asymptotically efficient, Feasible Generalized Least Squares (FGLS) estimator (Parks) sometimes performs poorly in finite samples. In a widely cited paper, Beck and Katz (1995) claim that their estimator panel-corrected SE (PCSE) is able to produce more accurate coefficient SE without any loss in efficiency in 'practical research situations'. This study disputes that claim. We find that the PCSE estimator is usually less efficient than Parks - and substantially so - except when the number of time periods is close to the number of cross sections.