اثر هزینه های معاملات، شرایط پرداخت و قدرت در سطح مواد اولیه موجودی

This paper proposes and tests an explanation for the level of raw materials inventories based on transaction cost economics theory and the role of power in a supply chain. According to this explanation, raw materials inventories are larger the higher a company's transaction costs and the lower its storage-related production and management costs. Factors that affect these costs are the company's vulnerability to opportunism, whether the input becomes more or less costly to store and manage as it moves through the supply chain, payment terms and the company's power in relation to its supplier. This explanation for the level of raw materials inventories was tested on a large sample of customer industries matched to their main supplier industries. Consistent with this theory, the empirical results show that companies hold larger raw materials inventories the more money their suppliers spend on research and development and the less important the customers are to their suppliers. These results are important because they indicate companies must consider a wider range of factors than previously thought necessary when establishing inventory policy.

The United States Census Bureau (2010) reported that U.S. companies held $1.36 trillion of inventories at the end of June 2010. This is a large investment that also is apparent in the manufacturing industries studied in this paper. Fig. 1 shows the distribution of total inventories as a percent of cost of goods sold held by companies in the sample industries over a 10-year period. Nearly two-thirds (62.23%) of the observations were of inventory levels between 10 and 30% of cost of goods sold. The average value of this ratio in the sample was 20.34% which corresponds to a days’-cost-in-inventory of approximately 74 days.2 Looked at another way, about 60% (59.89%) of the observations in the sample were for inventory levels of more than 10% of total assets.

This paper proposed and tested an explanation for the level of raw materials inventory based on transaction cost economics theory. This approach was chosen because storing raw materials can be considered a form of partial backward vertical integration undertaken to reduce transaction costs attributable to environmental (unintentional) and opportunistic (intentional) disruptions in supply. According to this theory, there are three reasons storing raw materials is a common and effective way to manage the costs of external supply. First, the parts in storage can used without delay and without any compromise in form or function regardless of how specialized they are or how specialized the customer and the supplier are to each other. Second, a raw materials inventory is a low cost form of self-insurance against supply risk because the customer can store the part in the same form and, except for economies of scale, at the same cost as its supplier or place the part in production to store it at a lower cost. Third, possessing a raw materials inventory is a deterrent to opportunism.