Product mixes as objects of choice in non-parametric efficiency measurement

Non-radial measures of technical efficiency essentially differ from their radial counterparts in that the product mix of the efficient reference is allowed to be different from the product mix of the evaluated observation. Whereas existing non-radial measures are still based on the product mix of the evaluated, i.e., possibly inefficient observation, we change the perspective and propose a measure based on the mix properties of the efficient reference. The resulting ‘inverse’ measure can be considered as complementary to the Färe–Lovell (or ‘Russell’) efficiency measure.