رویکردهای مبتنی بر تحلیل سلسله مراتبی برای ارزیابی تامین کنندگان : مشکلات و چشم اندازها

Supplier evaluation has assumed a strategic role in determining competitiveness of large manufacturing companies. An increasing number of researches have been devoted to the development of different kind of methodologies to cope with this problem. Nevertheless, while the number of applications is growing, there is little empirical evidence of the practical usefulness of such tools with a dichotomy between theoretical approaches and empirical applications. Considering this evidence, the goal of this paper is to contribute to understand the above dichotomy by implementing, in a corporate environment, a model for supplier evaluation based on the Analytical Hierarchical Process (AHP), one of the most prominent methodologies used to address the problem. The analysis of the implementation process of the methodology allows the identification of strengths and weaknesses of using formalized supplier selection models to tackle the supplier evaluation problem, also highlighting potential barriers preventing firms to adopt such methods. Relevant issues arising from the application and managerial implications for both customer and suppliers are discussed.

Outsourcing has always represented a key component of firms' strategy aimed at enhancing quality and competitiveness levels. The phenomenon has remarkably grown in the last few decades. Nowadays, in manufacturing companies, the purchasing share typically ranges from 30% to 90% of the total turnover (Ronchi, 2003). As a consequence, business management literature has highlighted the crucial importance of supplier relationships within a supply network (de Boer et al., 2001, de Boer et al., 2003, de Boer and van der Wegen, 2003, Bhutta, 2003 and Kamann and Bakker, 2004). Many have observed the need to move from an adversarial relationship perspective to one based on cooperation and reciprocal trust ( Hines, 1996, Cox and Lamming, 1997, Barrat, 2004 and Soosay et al., 2008). Others have stressed that selecting the appropriate suppliers represents a critical success factor for any outsourcing decision ( Dahel, 2003, Choy and Lee, 2003 and Prahinski and Benton, 2004). Indeed, the supplier evaluation process allows the selection of suitable suppliers in order to develop a supply relationship system able to rapidly react to market requirements and to innovation dynamics ( Reck and Long, 1988, Gules and Burges, 1996, Van Weele, 1999, Prahinski and Benton, 2004, Sarkara and Mohapatrab, 2006, Saen, 2007, Esposito and Passaro, 2009a and Esposito and Passaro, 2009b). An increasing number of researches have been devoted to the development of different kind of methodologies to cope with this problem. Nevertheless, while the number of applications is growing, there is little empirical evidence of the practical usefulness of such tools (Weber et al., 1991 and de Boer and van der Wegen, 2003). Very often, the proposed models are tested on generic applications, numerical examples and computational experiments (Bhutta and Huk, 2002, Dahel, 2003, Saen, 2007, Ting and Cho, 2008 and Ordoobadi, 2009), with less emphasis on the problems emerging in the practical implementation of the methodology, on its strengths and weaknesses, and on the appreciation given them by the practitioners and managers involved in decision making processes. Considering this evidence, the goal of this paper is to contribute to understand the above dichotomy by implementing, in a corporate environment, a methodology for supplier evaluation based on the Analytical Hierarchical Process (AHP), one of the most prominent methodologies used to address the problem (Saaty, 1980 and Saaty, 1994). After a thorough literature review, highlighting the relevance of the problem in the literature and the main methodologies employed to cope with the problem, the analysis of the implementation process of the methodology allows the identification of strengths and weaknesses of using AHP-based models (and, generally, formalized supplier selection models), also highlighting potential barriers preventing firms to adopt such methods. The paper is organized in 7 sections. Following this Introduction, in Section 2, an extensive analysis of published articles on the supplier selection problem during the last few decades is provided; in Section 3, a focus on AHP-based approaches for supplier selection is shown. The objectives of the research are then illustrated in Section 4, and some context information about the case study and the unit of analysis are provided in Section 5. The implementation of the AHP-based methodology is shown in Section 6, while Section 7 hosts a discussion of the lessons learned during the implementation process, after conclusions are drawn.

As it emerges from a thorough analysis of the current literature, the SSP is one of the most popular issues within the general topic of supply chain management. Quite often, models dealing with the SSP are just tested on numerical examples and/or computational experiments, with little attention to the problems, which arise in their practical implementation, with a little empirical evidence of the practical usefulness of such formalized tools in the practice. In order to contribute to understand the determinants of this dichotomy between theoretical approach and empirical application, an AHP-based model for supplier selection has been developed and applied to a real and complex case study. The literature survey has shown that among the numerous and different types of methodologies and techniques to cope with SSP, models based on Analytic Hierarchy Process (Saaty, 1980) and its extensions are the most widespread tool in the literature. Moreover, the survey has also highlighted that AHP based models can be used in combination with many other approaches. As regards the case study, the detailed implementation of the proposed methodology has been focused on the unit of analysis constituted by suppliers operating for AnsaldoBreda, the main Italian railway manufacturer, on a particular component of the traction system. The case study has allowed the identification of strengths and weaknesses of using formalized models to tackle the SSP, also highlighting potential barriers preventing firms to adopt such methods and various implications for customers and suppliers. Further researches will be devoted to a further and deeper understanding of the dichotomy between theoretical approach and empirical application in the SSP, by employing other formalized methodologies (for instance, based on Fuzzy Logic) and testing the benefits deriving from their implementation in a corporate context.