Sustainable supplier selection by using spherical fuzzy AHP

In today's highly competitive business market, the issue of sustainable supplier selection attracts great attention due to increased awareness of both social and environmental issues. The power of companies in the supply chain is determined not only by their own performance, but also by the power of other actors in the chain. As a field of study, the selection of sustainable suppliers remains its popularity because it requires developing a systematic procedure that addresses conflicting quantifiable and non-quantifiable factors simultaneously. In this study, one of the advanced fuzzy approaches called Spherical Fuzzy Sets (SFS) has been used to prioritize criteria that affect sustainable supplier selection. The proposed methodology combines the Spherical Fuzzy Sets and the analytic hierarchy process (AHP) and takes into account four main criteria: economic, quality, social and environmental criteria. In order to prioritize the main and sub criteria, questionnaires were conducted with three experts who have valuable experience in this field of study. After then, for the selection of the best sustainable supplier, a real selection problem in an international company was handled. The figured out ranking of the criteria and supplier alternatives can be used as a guide by the researchers and industrial experts who are responsible for sustainable supplier selection. To measure how much unit increase in weights assigned to key criteria affects supplier selection, a sensitivity analysis was carried out. It was noticed that the selection procedure for the selected company is not highly sensitive to changes.