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Demand Forecasting

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CHAPTER? DEMAND FORECASTING IN A S UPPLY CHAIN ~ Learning Objectives After reading this chapter, you will be able to: 1. Understand the role of forecasting for both an enterprise and a supply chain. 2. Identify the components of a demand forecast. 3. Forecast demand in a supply chain given historical demand data using time-series methodologies. 4. Analyze demand forecasts to estimate forecast error. F 7.1 orecasts of future demand are essential for making supply chain decisions. In this chapter, we explain how historical demand information can be used to forecast future demand and how these forecasts affect the supply chain. We describe several methods to forecast demand and estimate a forecast 's accuracy. We …show more content…

1 I i 7.2 CHARACTERISTICS OF FORECASTS Companies and supply chain managers should be aware of the following characteris­ tics of forecasts. 1. Forecasts are always wrong and should thus include both the expected value of the forecast and a measure of forecast error. To understand the importance of forecast error, consider two car dealers. One of them expects sales to range between 100 and 1,900 units, whereas the other expects sales to range between 900 and 1,100 units. Even though both dealers anticipate average sales of 1,000, the sourcing policies for each dealer should be very different given the difference in forecast accuracy. Thus, the fore­ cast error (or demand uncertainty) must be a key input into most supply chain deci­ sions. Unfortunately, most firms do not maintain any estimate of forecast error. 2. Long-term forecasts are usually less accurate than short-term forecasts; that is, long­ term forecasts have a larger standard deviation of error relative to the mean than short-term forecasts. Seven-Eleven Japan has exploited this key property to improve its performance. The company has instituted a replenishment process that enables it to respond to an order within hours. For example, if a store manager places an order by 10 A.M., the order is delivered by 7 P.M. the same day. Therefore, the manager only has to forecast what will sell that night less than 12 hours before the actual sale. The short lead time allows a manager to

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