متمم بین شیوه های خرید JIT : تجزیه و تحلیل اقتصادی مبتنی بر هزینه های مبادله

The objective of this paper is to analyse the complementarities and interrelationships between the different JIT purchasing practices which have extended in industrial markets in recent years. The incorporation of trust as an explicative element in a framework based on Transaction Costs Economics leads us to propose that the success of logistics-related JIT purchasing practices, which fundamentally transform the physical exchange process, depends on the implementation of additional practices which transform the way of governing and controlling the relationships and which support and rely on a co-operation climate. Empirical tests carried out over a sample of 148 Spanish auto components suppliers confirm this reasoning.

During the last decade or more, industrial supply structures have undergone significant changes derived from an evolution from adversarial relationships to co-operative relationships based on the generation of trust [1], [2], [3], [4] and [5]. This trend has given rise to concepts such as `partnership sourcing', `subcontracting’ or, when special attention is paid to logistics issues, `JIT purchasing'. The advantages of implementing JIT purchasing have been pointed out by several authors [6], [7], [8] and [9]. They tend to highlight the Japanese origin of such a way of managing the purchasing function and use comparisons between Western and Japanese plants as the basis of empirical studies. Nevertheless, JIT purchasing encompasses various groups of practices, whose interrelationships have scarcely been studied from an economics point of view. It is possible to distinguish between operational or logistical practices, which imply new physical ways of carrying out the transactions, and complementary practices, which imply new ways of governing and controlling such transactions. Most of the latter practices, to a greater or lesser extent, require, facilitate or generate mutual adaptation and co-operation between supplier and buyer. Some other practices aim at establishing controls and safeguards to assure reliability and competence on the part of the supplier. An important question that arises is: Is it possible to successfully implement operational practices without implementating complementary practices?, or, in a different way: Are there, indeed, complementarities between the two groups of practices? The distinction between operational and complementary practices, although not previously used in the literature, highlights the difference between implementing JIT delivery programmes with or without partnership sourcing arrangements. A number of works [2], [10], [11] and [12] report how suppliers are impaired when a partnering atmosphere does not accompany JIT programmes, that is, when purchasers try to reduce inventory without taking into account the whole JIT philosophy. The existence of complementarities between operational and complementary practices would provide evidence that this behaviour also prevents purchasers from realising many of the potential benefits associated with JIT purchasing. In order to answer the questions above, the paper is structured as follows. Firstly, a framework fundamentally based on Transaction Costs Economics (TCE) and incorporating trust as an explicative variable is introduced. This framework, in addition to overcoming some criticisms of TCE, leads to the existence of a certain space between pure market and hierarchy for co-operative relationships. Subsequently, in Section 2, this framework is applied to JIT purchasing and two hypotheses about the interconnections between operational and complementary practices and their consequences are posed. In Section 3, the empirical methodology to test the hypotheses is commented upon and, in the following section, the analysis and results are presented and discussed. The paper ends in Section 5 with a brief exposition of the main conclusions.

A TCE-based framework has been used to propose hypotheses about the relationships and complementarities between different practices which characterise advanced procurement techniques such as JIT purchasing. Firstly, the effect of trust on vertical relationships was analysed. It was theoretically shown how this element makes the market the most efficient governance structure for degrees of specificity and uncertainty in which traditional competitive relationships would not outperform vertical integration. Co-operative relationships, based on trust generation, displace vertical integration from certain intervals of medium specificity and uncertainty. Two groups of JIT purchasing practices, namely operational and complementary, were distinguished. The first group is inherent in JIT environments and it fundamentally affects the physical exchange process, whereas the second group of practices affects the way of governing and controlling the supply relationships. Complementary practices motivate and depend on the existence of trust and co-operation, but they also incorporate some safeguards related to the quality and reliability of suppliers. It was argued that the increase in specificity derived from the implementation of operational JIT purchasing practices raises transaction and production costs unless the firm promotes collaboration and mutual adaptation through complementary JIT purchasing practices. Nevertheless, companies might apply complementary practices separately, as a kind of partnership sourcing, without transforming their logistical processes. The empirical study carried out in the Spanish auto components industry has supported this reasoning. Those companies which implement operational practices also tend to implement complementary practices. Furthermore, among the companies with the lowest implementation levels of operational practices, two statistically different groups with respect to the implementation of complementary practices were identified. This proves that there are companies which choose to adopt more complementary practices even when their logistical processes continue to be managed with traditional procedures. A company may introduce more or less complementary practices and intensify collaboration and mutual adaptation with their suppliers to different degrees. According to the theoretical arguments used in this study, when the implementation of operational practices is high, the benefits directly derived from supply management rise as the company implements more and more complementary practices. This proposition has been confirmed over the 26 companies in the sample which have the largest degrees of implementation of JIT purchasing and, in particular, operational JIT purchasing. In addition, the sample reveals that the marginal benefits derived from the implementation of complementary practices are specially important when the company has reached certain implementation levels of operational JIT purchasing practices. Once again, a TCE framework provides economic arguments to explain behaviour patterns and change processes in the form of carrying out industrial relationships. In the same way, it permits the analysis of the complementarities and connections between advanced purchasing practices. Thus, in response to the question posed in the introduction, we conclude that the success of operational JIT purchasing practices depends on the presence of complementary practices. The isolated implementation of operational practices would not only bring about negative consequences for the suppliers, as pointed out in many works [2], [10], [11] and [12], but it would also prevent the buyer from realising many of potential benefits associated to the implementation of the whole package of JIT purchasing practices. New research proposals arise from this paper. Although the data analysis here addresses the links between complementary and operational practices, some more evidence about the links between these practices and firm efficiency should be generated. The implementation of the whole package of JIT practices seem to be better than the implementation of only some practices, but, does this global implementation lead to improved efficiency? Furthermore, in order to increase the validity of conclusions, more objective measures of results should be found and applied.