اندازه گیری کاهش تنوع در امتداد زنجیره تامین : مدل شکاف تنوع

To meet the demand for variety, many firms widen their product ranges, increasing not only revenues but also operational inefficiencies. Managerial choices can mitigate the negative effects on costs, but they also limit the ability of a firm to deliver variety to the market within the timeframe and costs requested by clients. Therefore, the variety actually offered in the market can be different from the level of variety that had been defined during, for instance, product development. We call the series of decisions whose interaction results in the variety actually distributed in the market the “process of variety reduction”. This paper introduces a descriptive model of this process. The model has been applied to a real case to highlight the main variety reduction decisions.

In real life supply chain systems, the retailer has the dominant power of controlling or influencing another member's decisions. Raju and Zhang (2005) summed up three salient characteristics of the dominant retailer: first, he has the ability to offer customers unprecedented opportunity for shipping and manufacturers effective promotional services; second, he is frequently the largest distributor for the supplier; third, he is frequently the price leader, for instance, the sales through Wal-Mart accounted for 19% of P & G's total sales in 2008, 40% of Tandy's and over 45% for many other large suppliers. Thus a retailer has the power to dictate prices of products. However, dominance of a retailer does not mean that he can decide prices and ordering quantities arbitrarily. So it is useful to propose a model, that is expected to help the retailer, in order to compute optimal price discounting policy not only to minimize the expected costs but also to make relationship sustainable. The retailers often try to stimulate the demand by offering price discounts. Price discounts offer economic benefits to consumers and influence consumers' beliefs about the brand which will increase consumers' purchase intentions. In real life, there are situations in which the retailer announces price discounts under advance payment scheme when an order from a customer is placed before the selling season. Further, if a customer pays an advance payment then he may get some price discount on the ordering quantity. For examples, in dairy-product manufacturing industries, the retailer announces price discount offer under AP scheme prior to the selling season. In India, to improve liquidity, a policy decision taken by the Maharashtra state co-operative cotton growers' federation is to give price discount to the customers who are making a payment (full or partial) in advance for the cotton. Paying a certain percentage of the total purchase cost per cycle as an AP to the retailer, the retailer can earn the interest on the amount of money via share market business or banking business. The customers can also save their money if they are sure about the necessity of a product. Thus the AP scheme is a real life phenomenon and it has a crucial impact on the inventory policies. In the classical logistics models, it was assumed that the retailers and their customers must pay for the items as soon as the items are received. However, in practices, the supplier/retailer would allow a specified credit period (say, 30 days) to their retailers/customers for payment without penalty to stimulate the demand of the consumable products. This credit term in financial management is denoted as ‘net 30’. Teng (2002) illustrated the benefits of trade credit policy: (1) it attracts new customers who consider trade credit policy to be a type of price reduction; and (2) it should cause a reduction in sales outstanding, since some established customer will pay more promptly in order to take advantage of trade credit more frequently. However, the strategy of granting credit terms adds an additional dimension of default risk to the supplier (Teng et al., 2005). Partial trade credit financing refers to paying partial amount for the purchased items as soon as the items are received and remaining amount should be settled at the end of a delay period, that is trade credit period. Before the end of the trade credit period, retailer can sell the goods and accumulate revenue and earn interest. A higher interest is charged if the payment is not settled by the end of the trade credit period. Partial trade credit financing is one of the central features in supply chain management. This paper investigates a supply chain model in which the supplier is willing to provide the retailer a full trade credit period for payments and the retailer offers the partial trade credit to his/her customer. This is called as two-echelon (or two-level) trade credit financing. In practice, this partial trade credit financing at a retailer is more matched to real life situations in a supply chain. The companies, like TATA and Toyato, can delay the full amount of purchasing cost until the end of the delay period offered by his suppliers. But these companies only offer partial delay payment to his dealership on the permissible credit period. Perishable products are commonly found in commerce and industry. Sometimes the rate of deterioration is too low, for items such as steel, hardware, glassware and toys, to cause consideration of deterioration in the determination of economic lot sizes. However, some items have a significant rate of deterioration, such as fruits, fresh fishes, perfumes, alcohol, gasoline and photographic films that deteriorate rapidly over time, which cannot be ignored in the decision making process of ordering lot size. The traditional EOQ models for perishable items can be found in the literature. Ghare and Schrader (1963) who derived a revised form of the economic order quantity (EOQ) model assuming exponential decay. Covert and Philip (1973) developed an EOQ model with Weibull distribution deterioration. Misra (1975) considered an EPQ model for deteriorating items with both varying and constant rate of deterioration. Balkhi and Benkherouf (1996) proposed a method for obtaining an optimal production cycle time of deteriorating items in a model where demand and production rates are functions of time. Many recent papers can be found in the literature related to deteriorating items. In the above models, the trade credit period option has not been considered. Recently, many researchers have given considerable attention to develop inventory models with trade credit period option. Goyal (1985) who established an EOQ model under the conditions of permissible delay in payments. Chung (1998) then developed an alternative approach to Goyal's problem. Chand and Ward (1987) analyzed Goyal's problem under assumptions of the classical economic order quantity model, obtaining different results. Aggarwal and Jaggi (1995), Chu et al. (1998), Chung et al. (2001), Hwang and Shinn (1997) and Shinn et al. (1996) extended Goyal's model to accommodate more real situations of deterioration of units in an inventory system. They considered a constant rate of deterioration. Chung (2000) obtained an alternative method to modify Shah's (1993) solution. Jamal et al. (1997) extended Aggarwal and Jaggi's (1995) model by allowing shortages. Jaggi and Aggarwal (1994) developed the credit financing in economic ordering policies of deteriorating items. Chung and Liao (2004) developed the economic order quantity for exponential deteriorating items under permissible delay in payments depending on the ordering quantity. There were several interesting and relevant papers related to the delay of payments such as those by Arcelus and Srinivasan (1993), Chung and Huang (2007), Chung and Liao (2006), Chung et al. (2005), Ouyang et al. (2005), Jamal et al. (2000), Khouja and Mehrez (1996), Kim et al. (1995), Salameh et al. (2003), Sarker et al., 2000a and Sarker et al., 2000b, Shinn (1997), Song and Cai (2006), Teng et al. (2005) and their references. Huang (2007) incorporated Huang (2003) to investigate the two-level trade credit policy in the EPQ frame work. Ho et al. (2008) developed an integrated supplier–buyer inventory model with the assumption that demand is sensitive to retail price and the supplier adopts a two-part trade credit policy. Huang and Hsu (2008) have developed an inventory model under two-level trade credit policy by incorporating partial trade credit option at the customers of the retailer. Liao (2008) developed an EOQ model with non-instantaneous receipt and exponentially deteriorating items under two-level trade credit financing. Teng and Chang (2009) extended the Huang (2007) model by relaxing the assumption N<MN<M. Jaggi et al. (2008) have developed a simple EOQ model in which the retailer's demand is linked to credit period. Tsao (2009) developed an EOQ model under the advance sales discount and two-level trade credit policy. Thangam and Uthayakumar (2009) developed an EPQ model for perishable items under two-level trade credit policy and selling price and credit period dependent demand. Chen and Kang (2010) developed integrated vendor–buyer inventory model with two-level trade credits and price negotiation scheme. Chang et al. (2010) have extended the Liao (2008) model by considering the case M<NM<N also. Balkhi (2011) has developed a finite horizon inventory model with deteriorating items under inflation and time value of money when shortages are not allowed. Liao et al. (2012) have developed a two warehouse lot-sizing model with order dependent trade credit period. Tsao and Sheen (2012) have developed a multi-item supply chain model with trade credit periods and weight freight cost. Unlike the previous models under two-echelon trade credit, this paper considers both the AP scheme and two-echelon trade credit option in a supply chain with perishable items. The retailer offers his customers a price discount if they can register their orders with AP prior to the sales period. As soon as the items are arrived to the inventory, the priority will be given to the customers who use AP scheme. The supplier provides the retailer a full trade credit period for payments whereas the retailer offers the partial trade credit to his customers who are not availing AP scheme. The customers must pay a portion of the purchase amount at the time of purchasing items and receive a trade credit period on the rest of the amount. To the best of our knowledge, this research is the first to incorporate the AP scheme and two-echelon trade credits into an EOQ-model for perishable items. Here, I not only find the optimal replenishment policy but also the price discounting policy by minimizing the retailer's costs under the AP scheme. Numerical examples incorporating with several managerial insights are also presented.

Though the advance payment scheme can be seen in practice, it has not been addressed till now in the area of two-echelon trade credits. This paper develops an EOQ model with perishable items incorporating both the advance payment scheme and the two-echelon trade credits. After formulating the model, solution procedures are developed to determine the optimal price discount rate and optimal cycle length for the dominant retailer. The managerial implications of numerical results are clear and provide suitable framework to assess the relative profitability. In future research, this model can be extended to three-echelon supply chains. One can also extend the model into more realistic assumptions, such as allowable shortages or finite replenishment rate.