In the nonparametric data envelopment analysis literature, scale elasticity is evaluated in two alternative ways: using either the technical efficiency model or the cost efficiency model. This evaluation becomes problematic in several situations, for example (a) when input proportions change in...

Radial and non-radial DEA models are distinguished on the basis of the presence of slacks. Viewing slacks as a possible source of inefficiency, this paper makes an empirical attempt to assess the relative strengths of these two sets of models in examining the total factor productivity change and...