Demand forecasting is part of a company’s overall inventory control activities. Inventory control is the process of ensuring your firm has an adequate supply of products and a wide enough assortment of them meet your customers’ needs. One of the goals of inventory management is to avoid stockouts. A stockout occurs when you run out of a product a customer wants to buy. Customers will simply look elsewhere to buy the product—a process the Internet has made easier than ever
When the attack on the World Trade Center occurred, many Americans rushed to the store to buy batteries, flashlights, American flags, canned goods, and other products in the event that the emergency signaled a much bigger attack. Target sold out of many items and could not replenish them for several days, partly because its inventory tracking system only counted up what was needed at the end of the day. Walmart, on the other hand, took count of what was needed every five minutes. Before the end of the day, Walmart had purchased enough American flags, for example, to meet demand and in so doing, completely locked up all their vendors’ flags. Meanwhile, Target was out of flags and out of luck—there were no more to be had.
To help avoid stockouts, most companies keep a certain amount of safety stock on hand. Safety stock is backup inventory that serves as a buffer in case the demand for a product surges or the supply of it drops off for some reason. Maintaining too much inventory, though, ties up money that could be spent other ways—perhaps on marketing promotions. Inventory also has to be insured, and in some cases, taxes must be paid on it. Products in inventory can also become obsolete, deteriorate, spoil, or “shrink.” Shrinkage is a term used to describe a reduction or loss in inventory due to shoplifting, employee theft, paperwork errors, or supplier fraud. 1
When the economy went into its most recent slide, many firms found themselves between a rock and a hard place in terms of their inventory levels. On the one hand, because sales were low, firms were reluctant to hold much safety stock. Many companies, including Walmart, cut the number of brands they sold in addition to holding a smaller amount of inventory. On the other hand, because they didn’t know when business would pick up, they ran the risk of running out of products. Many firms dealt with the problem by maintaining larger amounts of key products. Companies also watched their supply chain partners struggle to survive. Forty-five percent of firms responding to one survey about the downturn reported providing financial help to their critical supply chain partners—often in the form of credit and revised payment schedules. 2