Evaluating suppliers using gray data envelopment analysis With applying decision maker preferences

Organizations and companies in order to increase their capabilities in the business environment must increase the level of outsourcing of their activities, and this increases the dependence on suppliers., they must pay attention to the performance of their suppliers, and also the evaluation and selection of efficient suppliers creates a competitive advantage for companies. Recent studies have suggested many methods for evaluating and selecting suppliers. Data envelopment analysis due to the basis of mathematical programming and linear algebra is one of the powerful methods in this regard that measures the efficiency of homogeneous units with multiple inputs and outputs. On the other hand, due to the uncertainty of the data in real applications, this issue has become a complex decision-making. Gray number theory is a method used to deal with uncertainty conditions that has been used in this research. In the present study, two models for evaluating and selecting efficient suppliers and a method for ranking efficient units based on data envelopment analysis and gray data are presented. The first model is proposed in order to achieve real results by applying the priority of inputs and outputs by decision makers and the second model is proposed by reducing the volume of calculations and solving them in the issue of evaluation and selection of efficient suppliers. The two mentioned models have been used to evaluate the car glass suppliers of IranKhodro Company and the implementation of the model shows acceptable results from the implementation of the proposed models.