Kamran Moinzadeh

A supply chain model with direct and retail channels

Abstract We study a dual channel supply chain in which a manufacturer sells to a retailer as well as to consumers directly. Consumers choose the purchase channel based on price and service qualities. The manufacturer decides the price of the direct channel and the retailer decides both price and order quantity. We develop conditions under which the manufacturer and the retailer share the market in equilibrium. We show that the difference in marginal costs of the two channels plays an important role in determining the existence of dual channels in equilibrium. We also show that demand variability has a major influence on the equilibrium prices and on the manufacturer’s motivation for opening a direct channel. In the case that the manufacturer and the retailer coordinate and follow a centralized decision maker, we show that adding a direct channel will increase the overall profit. Our numerical results show that an increase in retailer’s service quality may increase the manufacturer’s profit in dual channel and a larger range of consumer service sensitivity may benefit both parties in the dual channel. Our results suggest that the manufacturer is likely to be better off in the dual channel than in the single channel when the retailer’s marginal cost is high and the wholesale price, consumer valuation and the demand variability are low.

The Impact of Information Technology Investments on Firm Performance and Evaluation: Evidence From Newly Industrialized Economies

The impact of information technology (IT)investments on firm performance has been the subject of active research in recent years. However, findings of almost all studies are based on data collected in the United States. Little work has been done elsewhere to validate these results and to see if they are applicable across national boundaries. In this study, we fill this gap by comparing four newly-industrialized economies (NIEs) with regard to the impact of IT capital on business performance. Secondary data collected from various sources are used to assess the impact over the period from 1983 to 1991. Findings based on four business measures and a market valuation model based on Tobins q are reported. While the current results are consistent with work done in the United States in general, discrepancies among the four NIEs are observed. Combined with findings from previous work, three pieces of evidence seem to emerge that are generally observed across country boundaries. First, IT investment is not correlated with shareholders return. Second, there is little evidence that the level of computerization is valued by the market in developed and newly-developed countries. Third, there is no consistent measurement of IT investment as indicated by the mixed results across different performance ratios. Modeling and measurement concerns expressed in previous U.S.-based studies are also observed in our comparative study. Our findings provide a starting point to accumulate a body of comparative studies for the development of a theory that links IT investment, firm performance, and macro factors such as national technology policy in an integrated framework.

A Multi-Echelon Inventory System with Information Exchange

In this paper, we consider a supply-chain model consisting of a single product, one supplier, and multiple retailers. Demand at the retailers is random, but stationary. Each retailer places her orders to the supplier according to the well-known ( Q,R) policy. We assume that the supplier has online information about the demand, as well as inventory activities of the product at each retailer, and uses this information when making order/replenishment decisions. We first propose a replenishment policy for the supplier, which incorporates information about the inventory position of the retailers. Then, we provide an exact analysis of the operating measures of such systems. Assuming the inventory/replenishment decisions are made centrally for the system, we compare the performance of our model with those that do not use information in their decision making, namely, systems that use installation stock policies via a numerical experiment. Based on our numerical results, we identify the parameter settings under which information sharing is most beneficial.

An ( S -1, S ) inventory system with emergency orders

In this paper, we develop an approximate model of an inventory control system in which there exist two options for resupply, with one having a shorter lead-time. We assume that demand and the fixed ordering costs are small relative to the holding cost so that a one-for-one ordering policy is appropriate. We consider a policy for placing emergency orders that uses information about the age of outstanding orders. We derive the steady-state behavior of this policy and present some computational results.

Two-Parameter Approximations For Multi-Echelon Repairable Inventory Models With Batch Ordering Policy

Abstract In this paper we present a model for multi-echelon repairable systems with batch ordering policy at the bases. Such an ordering policy is desirable when demand rates and/or the set up cost for ordering are relatively high. Operating characteristics of such a system are analyzed. A two-parameter approximation scheme for the distribution of the number of orders outstanding and consequently backorders is developed, and its performance evaluated. It is found that, under a variety of scenarios including both finite and infinite servers at the repair facility, the approximation scheme is very effective in providing a relatively simple means to determine the stocking levels at both the depot and the bases to minimize the cost of inventory holding and backorders. For the special case when the batch size is one, we confirm the effectiveness of the use of the negative binomial distribution as an approximation for the distribution of orders outstanding, as suggested by recent studies, under a much more gene...

Coordinating orders in supply chains through price discounts

In this paper, we examine the issue of order coordination between a supplier and multiple retailers in a decentralized multi-echelon inventory/distribution system where the supplier provides a product to multiple retailers who experience static demand and standard inventory costs. Specifically, we propose and analyze a new policy where a manufacturer, who outsources production to an Original Equipment Manufacturer, offers a price discount to retailers when they coordinate the timing of their orders with the manufacturers order cycle. We show that our proposed policy can lead to more efficient supply chains under certain conditions, and present a straightforward method for finding the manufacturers optimal price discount in this decentralized supply chain. A numerical experiment illustrates the managerial implications of our model as well as conditions when a manufacturer should consider adopting such a policy.

Operating characteristics of a two-echelon inventory system for repairable and consumable items under batch ordering and shipment policy

In this article we have generalized previous models on multiechelon recoverable inventory systems to cover the cases of batch ordering and shipment policy, and when items can either be repaired or condemned. The batch ordering and shipment policy is appropriate when the setup cost for shipment and order and/or the demand rates of the items are relatively high. The operating characteristics of such a system have been studied. Specifically, the probability distribution of backorder levels at the bases are analyzed for different repair-time distributions. An approximation scheme is proposed for this distribution, and is evaluated using extensive simulation results. The results indicate that the scheme is very effective in providing near-optimal stocking levels in such a system.

Adjustment Strategies for a Fixed Delivery Contract

We consider a long term contractual agreement between buyer and seller in whichQ units are delivered to the buyer at regular time intervals. It must be true that the delivery quantity,Q, is less than the mean demand per period. In order to manage the inventory, the buyer has the option of adjusting the delivery quantity upwards just prior to a delivery, but must pay a premium to do so. Demand is assumed random, and we model the system in a continuous review setting. We show that the equations one must solve to find optimal adjustment strategies are intractable. A diffusion approximation is developed which when coupled with the solution to an even simpler deterministic version of the problem yields very simple but effective approximations. Extensive computations are included to compare the performance of the optimal and approximate policies. We also empirically derive a formula for computingQ whose accuracy is established computationally. We prove that the fixed delivery contract results in lower variance of orders to the seller. We also include a computational study to find the unit cost discount that equalizes the expected costs for the fixed delivery contract and the base stock contract for a large parameter set.

An Information Based Multiechelon Inventory System with Emergency Orders

In this paper we study a (S-1, S) type multiechelon inventory system where all the stocking locations have the option to replenish their inventory through either a normal or a more expensive emergency resupply channel. When ordering a unit, each stocking location decides which channel to use based on its inventory level and the remaining leadtimes of the its outstanding orders. We consider the implications of this policy by developing expressions for the operating characteristics of the system and describing a procedure for finding the optimal policy parameters. A numerical study presented in the paper indicates that when alternative resupply modes are available our policy, which incorporates the information on the remaining leadtimes of the outstanding orders in selecting the resupply mode, can result in considerable cost savings when compared to policies which allow a single resupply mode.

A continuous-review inventory model with constant resupply time and defective items

As a result of imperfect production and inspection by suppliers, pilferage, and/or damage in transit, it is common that procurement orders may contain defective items. This article deals with a continuous-review inventory system with Poisson demand arrivals and constant resupply time. Items in resupply lots may not be of perfect quality. The operating characteristics of such a system are analyzed. For purposes of computational savings, an approximation scheme for the operating characteristics is presented. As a result of the approximation, the determination of the optimal ordering policy becomes much simpler. Extensive numerical tests suggest that the approximation scheme is very effective in giving the optimal or near-optimal ordering policies for such a system.