The directional distance function model is a generalization of the radial model in data envelopment analysis (DEA). The directional distance function model is appropriate for dealing with cases where undesirable outputs exist. However, it is not a units-invariant measure of efficiency, which...

Tone & Tsutsui (2010) introduced a hybrid model (epsilon-based measure, EBM), which combines both radial and non-radial measures in a unified framework [Tone, K., & Tsutsui, M. (2010). An epsilon-based measure of efficiency in DEA - A third pole of technical efficiency. European Journal of...

Data envelopment analysis (DEA) is a linear programming methodology to evaluate the relative technical efficiency for each member of a set of peer decision making units (DMUs) with multiple inputs and multiple outputs. It has been widely used to measure performance in many areas. A weakness of...

Directional distance function is the generalization of radial model in data envelopment analysis. It has the capacity of dealing with undesirable outputs, but the problem is that it has no unit-invariant measurement of efficiency, which hampers its application to empirical studies. Data...