Quality-based supplier selection and evaluation using fuzzy data

Since fuzzy quality data are ubiquitous in the real world, under this fuzzy environment, the supplier selection and evaluation on the basis of the quality criterion is proposed in this paper. The CpkCpk index has been the most popular one used to evaluate the quality of supplier’s products. Using fuzzy data collected from q⩾2q⩾2 possible suppliers’ products, fuzzy estimates of q   suppliers’ capability indices Cpki(i=1,2,…,q) are obtained according to the form of resolution identity that is a well-known theorem in fuzzy sets theory. Certain optimization problems are formulated and solved to obtain αα-level sets for the purpose of constructing the membership functions of fuzzy estimates of CpkiCpki. These membership functions are sorted by using a fuzzy ranking method to choose the preferable suppliers. Finally, a numerical example is illustrated to present the possible application by incorporating fuzzy data into the quality-based supplier selection and evaluation.