A NOTE ON INTEGRATING INVENTORY AND PRODUCT SALES-MIX MODELS

In a recent issue of Decision Sciences, Raiborn and Harris [2] discussed the integration of inventory and product sales-mix models. While they formulated a model which reflected some of the interactions between product sales-mix and inventory decisions, the purpose of this note is to point out deficiencies in their decision rule analysis for solving such integrated models.     

APPLYING SCENARIO‐DRIVEN STRATEGY TO INTEGRATE ENVIRONMENTAL MANAGEMENT AND PRODUCT DESIGN

The successful development of breakthrough products with environmental attributes can not only create competitive advantage through operations excellence but also benefit the environment. This paper proposes a comprehensive scenario‐driven method with detailed implementation steps for planning and developing breakthrough products with environmental attributes. A case study based on the development process of biotechnology products is presented to show the applications of the method and the resulting importance of flexibility as a key ingredient in operations strategy. The paper also discusses various operational, marketing, technological, economic, and environmental issues concerning the development of biotechnology products, an area that could have a significant impact on both human health and the natural environment.     

THE INTERACTION OF TRANSPORTATION AND INVENTORY DECISIONS

The management of inventories and determination of transportation policy are normally carried out by different groups of people in an organization. These activities interact, however, when the transportation is used to replace inventory and when the transportation alternatives have different speed, reliability, and cost characteristics. This paper presents exact and heuristic procedures for jointly determining the inventory reorder points, order quantities, and transportation alternatives that provide minimum total transportation and inventory costs. The effectiveness of each procedure is demonstrated for a broad range of problems. The heuristic procedure was also applied to actual company data to determine the potential for cost savings. The results showed that savings were possible both from improving the current procedures and from applying the procedure developed in this study.     

EXPLORING LINKAGES BETWEEN MANUFACTURING STRATEGY,BUSINESS STRATEGY,AND ORGANIZATIONAL STRATEGY

In recent years there has been an increased emphasis on the development of manufacturing and business strategies. In spite of that high level of emphasis, limited empirical research has been published on the linkage between manufacturing strategy, business strategy, and organizational performance. Our study examines that linkage. Our main contribution lies in (i) building constructs for some important elements of manufacturing strategy and business strategy and (ii) testing the impact of linkage between manufacturing strategy and business strategy on organizational performance. The study is based on 175 responses from senior executives in manufacturing organizations.     

MULTI-MACHINE,MULTI-PRODUCT PRODUCTION SCHEDULING AND INVENTORY CONTROL

This paper deals with a multi-machine, multi-product lot size determination and scheduling problem. The model developed here considers not only the usual inventory-related operational cost, but also the costs that depend on under- or over-utilization of available men and machines. It penalizes overtime or idle time at any facility. The solution minimizes the inventory and resource-related costs and not just inventory costs. A heuristic is developed to determine the solution from the model and to modify it, as necessary, to obtain a conflict-free, repetitive, and cyclic production schedule for an infinite horizon. Although this model is developed for a manufacturing situation, the words machine, job, and machine shop are used in a symbolic sense, and hence the model can be used in practice in a variety of circumstances.     

INVENTORY MANAGEMENT AND CAPITAL BUDGETING: A PEDAGOGICAL NOTE

This paper shows, through an alternative development of the lot size model, how the methods of capital budgeting can be logically applied to the determination of optimal inventory levels. There is no reason why inventory management needs be treated any differently than the management of fixed assets. The rule that the stock of fixed assets should be expanded until the marginal rate of return equals the marginal cost of capital results from maximizing the present value of profits as a function of the investment level. In a like manner, the “square root” formula from inventory theory results from maximizing the present value of profits as a function of the investment in inventory. In addition, formulating the inventory problem as a capital budgeting problem has advantages for incorporating deterioration, obsolescence, and other costs into the model in a more logical and less intuitive way.     

STOCK LEVELS AND DELIVERY RATES IN VENDORMANAGED INVENTORY PROGRAMS

Using the latest information technology, powerful retailers like Wal‐Mart have taken the lead in forging shorter replenishment‐cycles, automated supply systems with suppliers. With the objective to reduce cost, these retailers are directing suppliers to take full responsibility for managing stocks and deliveries. Suppliers' performance is measured according to how often inventory is shipped to the retailer, and how often customers are unable to purchase the product because it is out of stock. This emerging trend also implies that suppliers are absorbing a large part of the inventory and delivery costs and, therefore, must plan delivery programs including delivery frequency to ensure that the inherent costs are minimized. With the idea to incorporate this shift in focus, this paper looks at the problem facing the supplier who wants quicker replenishment at lower cost. In particular, we present a model that seeks the best trade‐off among inventory investment, delivery rates, and permitting shortages to occur, given some random demand pattern for the product. The process generating demand consists of two components: one is deterministic and the other is random. The random part is assumed to follow a compound Poisson process. Furthermore, we assume that the supplier may fail to meet uniform shipping schedules, and, therefore, uncertainty is present in delivery times. The solution to this transportationinventory problem requires determining jointly delivery rates and stock levels that will minimize transportation, inventory, and shortage costs. Several numerical results are presented to give a feel of the optimal policy's general behavior.     

NEW PRODUCT ANNOUNCEMENTS AND STOCK PRICES

The final test of any management decision is its effect on the value of the firm's securities. This paper examines the subsequent impact of the publication of new product announcements on stock returns. A distinguishing feature of this presentation is the integration of decision making in the marketing and finance functional areas.     

INVENTORY RATIONING AND SHIPMENT FLEXIBILITY ALTERNATIVES FOR DIRECT MARKET FIRMS

This paper investigates inventory‐rationing policies of interest to firms operating in a direct market channel. We model a single product with two demand classes, where one class requests a lower order fulfillment lead time but pays a higher price. Demand for each class follows a Poisson process. Inventory is fed by a production system with exponentially distributed build times. We study rationing policies in which the firm either blocks or backlogs orders for the lower priority customers when inventory drops below a certain level. We compare the performance of these rationing policies with a pure first‐come, first‐serve policy under various scenarios for customer response to delay: lost sales, backlog, and a combination of lost sales and backlog.     

CAMPBELL SOUP'S CONTINUOUS REPLENISHMENT PROGRAM: EVALUATION AND ENHANCED INVENTORY DECISION RULES

Campbell Soup's continuous replenishment (CR) program is a novel innovation designed to improve the efficiency of inventory management throughout the supply chain. With CR (1) retailers pay a constant wholesale price but continue to participate in consumer promotions, (2) retailers transmit to the supplier daily inventory information via electronic data interchange (EDI), and (3) the supplier assumes responsibility for managing retailer inventories, i.e., vendor managed inventories (VMI). We develop simple inventory management rules to operate CR, and we test these rules with a simulation using actual demand data provided by Campbell Soup. On this sample we find that retailer inventories were reduced on average by 66% while maintaining or increasing average fill rates. This improvementreduces a retailer's cost of goods sold by 1.2%, which is significant in the low profitmargin grocery industry. Furthermore, these savings could have been achieved without VMI.     

CONTROLLING EMPLOYEE THEFT THROUGH TIME AND PRODUCT IDENTIFICATION

No abstract available for this article.     

DECENTRALIZED MULTIECHELON INVENTORY CONTROL

This paper considers a model for decentralized control of an inventory system consisting of 1 central warehouse and a number of retailers. The cost structure includes holding costs at both echelons and shortage costs proportional to the time until delivery at the retailers. We analyze a procedure for coordinated but still decentralized control of the system. The procedure is based on a simple approximation, in which the stochastic lead times perceived by the retailers are replaced by their correct averages. The approximation enables us to decompose the considered multiechelon inventory problem into a number of single echelon problems, 1 for each installation. The information about how a certain decision at the warehouse affects the retailers is conveyed through the marginal cost increase with respect to a change of the expected lead time. This information about the retailer costs is used as a shortage cost at the warehouse. We show that a coordination procedure based on this information can be used for finding near-optimal reorder points for the system and provide bounds for the approximation errors.     

INVENTORY DECISIONS UNDER INFLATIONARY CONDITIONS

The standard approach to inventory policy ignores the effect of inflation. This paper investigates a model that includes both inflationary trends and time discounting. The paper compares this model with the standard EOQ model and the analysis for a one-time change, found in previous literature.     

AN EMPIRICAL EVALUATION OF CONSTANT AND ADAPTIVE COMPUTER FORECASTING MODELS FOR INVENTORY CONTROL

This study compares the performance of one constant model with two adaptive models. MAD and bias were used as criteria for evaluating performance. The results of testing the adaptive models with the constant model were contrary to the expected better performance of the adaptive models; no significant differences were found between the models over known horizontal, trend, and seasonal demand patterns. However, some of the practical advantages of adaptive forecasting models in business suggest their continued use.     

PRODUCT MARKET REGULATION,FIRM SELECTION,AND UNEMPLOYMENT

This paper analyzes the effect of product market regulation (PMR) on unemployment in a search model with heterogeneous multiple‐worker firms. In our setup, PMR modifies the distribution of firm productivities, thereby affecting the equilibrium rate of unemployment. We distinguish between PMR related to entry costs and PMR that generates recurrent fixed costs. We find that: (i) higher entry costs raise the rate of unemployment mainly through our novel selection effect, (ii) higher fixed costs decrease unemployment through the selection effect and increase it through the competition effect analyzed in Blanchard and Giavazzi (2003, Quarterly Journal of Economics, 118, 879–907). Firm heterogeneity magnifies the impact of both types of regulatory costs. We propose econometric evidence consistent with the unemployment effects of sunk versus recurring costs.     

INTEGRATED COMPONENT AND SUPPLIER SELECTION FOR A PRODUCT FAMILY

This paper examines the reduction in complexity of a product family through product design. By leveraging the commonalities among products in a family, the decision support methodology presented in the paper helps choose components and suppliers that minimize the sum of design, procurement, and usage costs. The problem of integrated component and supplier selection is conceptualized and formulated as an integer-programming model. Analysis of the model yields two properties, complete and continuous replacement, which form the basis of a heuristic procedure. Computational tests show that the heuristic provides results close to the optimal solution and can be used for selecting components and suppliers. Application of the model to an industrial problem is discussed.     

RETAIL INVENTORY CONTROL WITH LOST SALES,SERVICE CONSTRAINTS,AND FRACTIONAL LEAD TIMES

This paper describes a periodic review, fixed lead time, single-product, single-facility model with random demand, lost sales and service constraints that was developed for potential application at a Western Canadian retailer. The objective of this study was to determine optimal (s, S) policies for a large number of products and locations. To this end, we evaluate the long run average cost and service level for a fixed (s, S) policy and then used a search procedure to locate an optimal policy. The search procedure is based on an efficient updating scheme for the transition probability matrix of the underlying Markov chain, bounds on S and monotonicity assumptions on the cost and service level functions. A distinguishing feature of this model is that lead times are shorter than review periods so that the stationary analysis underlying computation of costs and service levels requires subtle analyses. We compared the computed policies to those currently in use on a test bed of 420 products and found that stores currently hold inventories that are 40% to 50% higher than those recommended by our model and estimate that implementing the proposed policies for the entire system would result in significant cost savings.     

MANAGING PRODUCT VARIETY: AN INTEGRATIVE REVIEW AND RESEARCH DIRECTIONS

Variety management has emerged as a crucial dimension of successful business practice. In this paper, I first provide a framework for managerial decisions about variety. Variety‐creation decisions determine the amount, type, and timing of end‐product variety, while variety‐implementation decisions focus on the design and operation of internal processes and a supply chain to support a firm's variety‐creation strategy. I organize variety‐related decisions into four key decision themes in variety creation: 1) dimensions of variety, 2) product architecture, 3) degree of customization, and 4) timing; and three key decision themes in variety implementation: 1) process capabilities, 2) points of variegation, and 3) day‐to‐day decisions. I describe each theme and review the relevant literature on each theme, with a focus on research that provides insight to problems faced in practice. Finally, I identify untapped avenues for future research that would be of value to the practicing manager, paying special attention to interdependencies among decision themes.     

QUANTIFYING THE IMPACT OF INVENTORY HOLDING COST AND REACTIVE CAPACITY ON AN APPAREL MANUFACTURER'S PROFITABILITY

This paper was motivated by the operational problems faced by Northco, a school uniform manufacturer in the Northeastern United States. Northco was facing high working capital costs while also incurring high stockout and markdown costs. This paper models the impact of inventory holding cost and reactive capacity on Northco's targeted understocking and overstocking cost and offers a solution methodology for such problems. We quantify the impact of varying inventory carrying costs (and hence, high working capital costs) on stockout costs and the value of additional capacity. Our results illustrate that apparel manufacturers with high working capital costs, and hence high inventory carrying costs, should target higher stockout costs and achieve lower capacity utilization. The results presented have application beyond Northco because high working capital cost is endemic to many supply chains.