هماهنگی زنجیره تامین با قراردادهای تخفیف فروش و مدیریت موجودی فروشنده

Coordinating supply chains is an effective way to improve channel performance. This paper details how a sales rebate contract helps achieve supply chain coordination which allows decentralized decisions of chain members to perform a centralized decision for the whole system. A model in the context of a two-echelon supply chain with a single supplier serving multiple retailers in vendor-managed inventory (VMI) partnership is proposed. VMI facilitates the application of the sales rebate contract since information sharing in VMI partnership allows the supplier to obtain actual sales data in a timely manner and determine the rebate for retailers. Retailers are considered in two scenarios: independent retailers with a demand function sensitive only to their own price and competing retailers with a demand function depending on all retailers’ prices. The proposed model demonstrates that the supplier gains more profit with competing retailers than without as competition among the retailers lowers the prices and thus stimulates demand.

In today's global market, more and more companies realize that the performance of their businesses depends largely on external collaboration and coordination across the supply chain. As chain members are primarily concerned about their individual interests which may not contribute to the overall supply chain performance, their decisions may result in an inefficient network system with problems like high costs, compromised customer service and a weakened strategic position (Fugate et al., 2005). Much research focuses on coordination schemes achieving supply chain coordination, particularly the type of contractual arrangement that is required for coordination (Cachon, 2003). The sales rebate contract is one of the contracts that coordinate the supply chain with one compliance regime, and channel rebates are widely adopted in the hardware, software and auto industries (Taylor, 2002). A rebate is different from an order quantity discount as it only applies to items sold to end-users. Hence, a rebate contract is more efficient than an order quantity discount because it provides a direct incentive for retailers to increase sales. However, it is difficult to implement a sales rebate contract in a traditional supply chain, mainly because a traditional supply chain does not have a mechanism to facilitate continuous information exchange between chain members. The supplier needs to know the exact quantity sold by the retailer in order to pay the rebate but difficulties arise when the supplier cannot acquire the retailer's sales data directly. On the other hand, the data obtained from the retailer may not be authentic as the retailer may claim more rebates than what the actual sales allow. Difficult administration is probably the reason for a preference for an order quantity discount over a sales rebate, despite the fact that a sales rebate is a better sales incentive. When the vendor-managed inventory (VMI) partnership was proposed and put into practice, the situation has since been changed. The supplier monitors the retailer's inventory levels (physically or via electronic messaging) and makes periodic replenishment decisions in terms of quantity and frequency. As the sales quantity is made known to the supplier, it provides a basic condition for feasibility of a sales rebate. The supplier can obtain more information for analysis, such as customer preferences and sales performance influenced by the retail prices through electronic data interchange (EDI) and points of sales (POS). VMI partnership thus facilitates the implementation of the sales rebate contract. In this study, the sales rebate contract in VMI partnership is examined to see how it achieves supply chain coordination so that each member's decisions is aligned with the global supply chain's objectives. A two-echelon supply chain composed of a single supplier and multiple retailers is also examined. In VMI partnership, the supplier adopts a periodic review policy to replenish inventory for each retailer. The supplier first determines a base-stock level for each retailer conditioned by the customer service level (CSL), and then in every replenishment period increases the retailers’ inventory up to the base-stock level. Each retailer faces a comparatively stationary stochastic demand as the demand distribution is almost identical in every period. The rebate contract has the effect of motivating retailers to lower prices for increasing sales, so it is a good application for system coordination. Taylor (2002) discussed a rebate contract which coordinated a supply chain composed of one supplier and one retailer, in which retailers were allowed to determine their order quantities consistent with the optimal order quantities so as to optimize the global supply chain's profit. Different from Taylor's work, our study addresses a VMI system in which retailers are not concerned about order decisions but only price choices, and therefore how to coordinate retailers’ price decisions with the global supply chain objective is the main concern. In addition, two different scenarios are addressed in this study: an independent retailer with a demand function only sensitive to individual prices, and competing retailers with a demand function depending on other retailers’ prices. The coordinated results are compared in the two scenarios, and the impact of the competition on coordination is investigated. The main contribution of this study is to propose a coordination scheme for VMI partnership through the sales rebate contract. VMI partnership facilitates the application of the rebate contract because information sharing in VMI partnership allows the supplier to gain actual sales data, which is a necessary condition for implementing the sale rebate contract. The idea of how the sales rebate contract in VMI partnership influences decentralized supply chain coordination has rarely been mentioned in the related literature, especially the insight into the influence of competition among heterogeneous retailers on the chain coordination. The remainder of this paper is organized as follows. The next section reviews the related literature. Section 3 defines the notation used and specifies the proposed model. Section 4 studies the model with independent retailers and presents the impact of the sales rebate contract on supply chain coordination. Section 5 addresses the case of competing retailers and the impact on chain coordination. The final section discusses the results and a conclusion is made.

This study examines a two-echelon supply chain with a single supplier and multiple retailers based on the newsvendor model, in which the retailers face stochastic demand sensitive to the retail price. A VMI partnership mode is formulated in our model and the supplier adopts a sales rebate contract to stimulate retailers to increase sales. The results demonstrate that when the sales rebate contract combines with the VMI mechanism, the supply chain achieves perfect coordination, which means that retailers acting strategically in their individual interests can also make price decisions to maximize the aggregate chain profit. Because of a proper rebate contract, the retailers lower prices to the system-wide optimal prices so as to increase demand and further improve the aggregate chain profit. Two different cases are examined involving independent retailers and competing retailers with price competition. This study demonstrates that the intensity of the competition influences the profit allocation between the supplier and retailers, greater profit is allocated to the supplier when the competition becomes more intense. It will be interesting to explore other extensions of the model. The model with non-stationary stochastic demand in different periods should also be studied. Given the dynamic demand correlated in the continuous time interval, the supplier can adjust the wholesale price and the rebate contract based on the predicted demand quantities in the next replenishment period. Therefore, it may be promising to investigate the dynamic strategies for supply chain coordination.