Färe and Grosskopf (this issue) claim that a single abatement factor suffices for modeling weak disposability in nonparametric production models, and that the <xref ref-type="bibr" rid="R3">Kuosmanen (2005)</xref> technology that uses multiple abatement factors is larger than necessary. This article demonstrates by a numerical...

In a production technology, the type of returns to scale (RTS) associated with an efficient decision making unit (DMU) is indicative of the direction of marginal rescaling that the DMU should undertake in order to improve its productivity. In this paper a concept of global returns to scale (GRS)...