یک مدل فازی یکپارچه برای مدیریت تامین کننده: یک مطالعه موردی از انتخاب ISP و ارزیابی

Supplier selection is a multi-criteria decision-making problem which consists of both qualitative and quantitative metrics. A lot of investigations have been published in the supplier selection area and it has been notified that in the majority of these publications supplier selection and evaluation and development have the same meaning. However, one needs integrated models to cover all of these stages. In addition, most of the proposed models focused on manufacturing environments and a few papers have been allocated for service industries. To our knowledge, no Internet service provider (ISP) selection and evaluation has been published up to now. In this paper, we propose a new framework on the basis of company’s strategy for supplier management including supplier selection, evaluation, and development. In the first phase, quality function deployment (QFD) is utilized to rank the best ISPs based on qualitative criteria. Then, a quantitative model is adopted to consider quantitative metrics. Finally, we compose two models and select the best ISPs. In the next phase, we propose a novel algorithm to evaluate selected ISPs from three perspectives: customer, performance, and competition. Meanwhile, the fuzzy logic and triangular fuzzy numbers are utilized to deal with vagueness of human thought. Furthermore, a case study is conducted to illustrate the stages of ISP selection and evaluation. The implementation of the proposed model is easy and do not need optimization background.

Supply chain management (SCM) has generated a substantial amount of interest both among managers and researchers. SCM is now distinguished as a governing element in strategy and as an effective way of creating value for customers. A structure of supply chain is composed of potential suppliers, producers, distributors, retailers and customers, etc. (Fiala, 2005). Therefore, suppliers play an important role in achieving the objective of supply management. They enhance customer satisfaction in a value chain. Hence, strategic partnership with better performing suppliers should be integrated within the supply chain for improving the performance in many directions including reducing costs by eliminating wastages, continuously improving quality to achieve zero defects, improving flexibility to meet the needs of the end-customers, reducing lead time at different stages of the supply chain, etc. (Kumar, Vrat, & Shankar, 2004). Manufacturing cannot forecast demand precisely, and they prefer to manage suppliers via different methods such as supplier development, supplier evaluation, supplier selection, supplier coordination, etc. (Chou & Chang, 2008). The objective of supplier selection is to identify suppliers with the highest potential for meeting a firm’s needs consistently and at an acceptable cost (Kahraman, Cebeci, & Ulukan, 2003). In the supplier selection process a pool of suppliers is chosen for procurement according to a predefined set of criteria (Aissaoui, Haouari, & Hassini, 2007). While several methods have been proposed and utilized for evaluation and selection of suppliers, they have limitations including: evaluation solely based on operational metrics, simple weighted scoring methods based on subjective assessments, and lack of relative evaluation across various suppliers (Talluri & Narasimhan, 2004). In addition, the majority of previous investigations have focused on supplier selection or supplier evaluation or supplier development separately. We aim to develop an integrated model for supplier management and fill the gap in the literature. Besides, the new model combines both qualitative and quantitative criteria simultaneously. Moreover, unlike the case of parts purchasing, there is only a limited number of studies that model the service supplier selection problem (Aissaoui et al., 2007, De Boer et al., 2001 and Degraeve et al., 2004). In this article, we propose a novel model for Internet service provider (ISP) selection and evaluation which can be applied for most of the service sectors. In addition, most published models in this area focus only on the customer perspective or supplier’s performance perspective, or competition situation, and hence these models pay no attention to all of these factors simultaneously. In order to solve the above shortages we propose a novel method that considers competition position, current performance and customers’ viewpoint concurrently. This paper proposes a decision model that consists of two phases. In the first phase, QFD model will be integrated with a quantitative model to select the best ISPs. In the second phase, the selected ISPs will be evaluated based on a novel algorithm. Furthermore, special attention is paid to the various subjective assessments in the selection and evaluation process by using triangular fuzzy numbers. Meanwhile, a case study is conducted to illustrate the proposed model. The model can be easily implemented with spreadsheet packages. The organization of this paper is as follows. Section 2 discusses the literature review. Quality function deployment is introduced in Section 3. Section 4 describes fuzzy set theory. Next, case review (case of suppliers’ selection in ISP service sector) is presented in Section 5. Section 6 introduces ISP selection approach. Subsequently, Section 7 presents ISP evaluation process. Furthermore, sensitivity analysis is presented in Section 8. Finally, conclusions are presented in Section 9.

In this paper, we have proposed a new model for ISP selection and evaluation problem. After problem definition in a case of ISP sector, we proposed the most important criteria based on ADSL’s attributes. We utilized a combination of fuzzy QFD model and a quantitative model for ISP selection. Then, we proposed a novel algorithm for ISP evaluation which enabled us to identify the weaknesses and assess the performance of each ISP. Triangular fuzzy numbers have been utilized to deal with imprecision in human thought. The model can be applied to practical situations and can be easily implemented by spread sheet packages. The principal advantages of our model are in sixfold: First, we combined supplier selection, evaluation and development together and proposed a new framework for supplier management. Second, we focused on supplier selection and evaluation in service industries specially Internet Service Provider selection and evaluation problem. Third, the proposed model can rate both qualitative and quantitative criteria and select suitable suppliers effectively. Fourth, the model considers customer, competition, and performance simultaneously. Fifth, the proposed approach can adequately deal with the inherent uncertainty and imprecision of human decision-making. Finally, this research investigated the differences among decision-makers by devoting unequal weights. There are many opportunities for future works in this field. For example, it is valuable to add ISP development stage to the proposed model and examine the results in practical environments. Furthermore, some ISPs may have proposed different discount policy to vend Internet services. Therefore, it is worthwhile to analyze the effects of discounts and modify the model. Besides, comparing the results of proposed method with fuzzy DEA will be another research topic. It is expected that in the near future, this integrated model will be applied effectively to various issues such as performance assessment, business strategies, policy making, personnel and employee selection.