Estimated Returns to Scale with Interval Data in Parallel Manufacturing Systems with Shared Resources

Many models in DEA have been proposed to estimate returns to scale. Determining the nature of returns to scale has considerable of importance in the theory of production.Knowing the fact that returns to scale is a constant, ascending or descending decision making unit, proper actions can be performed to develop the decision making units. In this study, the efficiency of parallel production systems with shared resources is evaluated such that the data is inexact and interval, so the function of these systems is interval too.Then a model is proposed to estimate returns to scale of interval data on these systems;when the data is inexact, the nature of returns to scale of these units is inexact too, so returns to scale is estimated as multiple in best and worst conditions.