A decision model proposal for sustainable supplier selection and an application

In today's competitive and sustainability-focused business environment, supplier selection has become a critical factor in ensuring long-term success. This study aims to develop a supplier selection model from a sustainability perspective by applying it to the selection of IT outsource suppliers for a company. Based on a comprehensive literature review, 27 sustainability criteria were identified, covering economic, social, and environmental dimensions. To prioritize these criteria, the Analytic Hierarchy Process (AHP) was used, and 6 procurement experts were consulted during this process. Subsequently, supplier firms' representative rated their own companies for each criterion on a scale of 1 to 5. Using the Grey Relational Analysis (GRA) method, the suppliers' performances were evaluated and ranked. Initially, price quotations were not considered; however, the grey relational degrees were later converted into cost criteria, and price quotations were integrated. As a result, the final supplier ranking, which considers both sustainability and cost criteria, was obtained. This study contributes to the literature on sustainable supplier selection and presents a model that encourages businesses to collaborate with suppliers aligned with their long-term strategic goals. Keywords: Sustainable Supplier Selection, IT Outsourcing, Analytic Hierarchy Process (AHP), Grey Relational Analysis (GRA), Supplier Performance