Undesirable factors in efficiency measurement

Many production processes yield both desirable factors (inputs/outputs) and undesirable ones. There are some models that evaluate efficiency level in the presence of undesirable factors. The current models consider only undesirable outputs (inputs). In this paper we propose a model for treating such factors in the framework of Data Envelopment Analysis (DEA). The proposed model considers both of the undesirable factors and we discuss efficiency measurement in the context of the model. A numerical example is given.