A data-based comparison of the two undesirable output disposability approaches in environmental efficiency

Data envelopment analysis (DEA) was originally developed to evaluate entities that carry out production processes in which multiple inputs are converted into multiple outputs. Subsequent advancement in DEA literature also points out the production of undesirable outputs. The most common approach which has attracted the researcher attention was the assumption of weak disposability. This axiom makes the proportional reduction for desirable and undesirable outputs in underlying technology. Linking to individual-proportion reduction of bad outputs, this study aims to reveal the contribution of non-disposed inputs or the idle inputs in production process. Toward this end, a simple modification is presented. The modified model demonstrates the effect of pointless inputs in reduction undesirable outputs and implies that fading their effect may improve the efficiency measure and optimize the performance. A real example compares the results and illuminate the model practicality.