Schmidt, Peter; Alvarez, Antonio; Amsler, Christine - Econometric Society - 2004
their levels of technical inefficiency. Let u ≥ 0 be the one-sided error reflecting technical inefficiency, and let z be a … least squares; it allows a distribution-free interpretation of the parameters δ that show how z affects inefficiency; and … to allow correlation over time when inefficiency depends on firm characteristics. The paper shows how to test the …