Evaluating the Congestion Effect in the Two-Stage Structures by NDEA Models

Document Type : Original Article



Congestion is an important issue in economics and data envelopment analysis (DEA). It occurs when one or more outputs can be increased by reducing one or more inputs, without worsening any other input or output. In recent years, there have been various studies dealt with two-stage production systems by DEA models. These systems consume some inputs in their first stage to produce some intermediate outputs which are used as the inputs of the second stage in producing final output.  So far, it is not much attention to the existence of the congestion effect in these structures. In this article, we have focused on a congestion effect on the two-stage structures via network DEA models. In addition, this study proposes a new method for measuring congestion in divisions of the network. This model can evaluate congestion in the network structure and identify that which factors cause of the congestion