Case: When HP checked printer sales at a major retailer, they found that the retailer's sales fluctuated over time. When they checked the retailer's orders, they found that the orders fluctuated more than other retailers. Sales fluctuate even more. What surprised them even more was that the orders provided by the company's printer production department to the material supply department fluctuated more than the previous two. This is the so-called "bullwhip" effect. The "bullwhip" effect occurs because demand information is constantly misinterpreted as it travels up the supply chain. The company's product delivery falls victim to orders that are inflated by retailers; in turn it further inflates orders to suppliers. The “bullwhip” effect leads to excess inventory in the supply chain. Research shows that across the entire supply chain, from the time a product leaves a manufacturer's production line until it reaches a retailer's shelf, the average product inventory time is more than 100 days. Distorted demand information causes each individual in the supply chain to increase inventory accordingly. Relevant reports estimate that more than $30 billion is deposited in the food supply chain in the United States, and the situation in other industries is similar. The "bullwhip" effect also leads to poor corporate production forecasts. The inability to process the backlog of orders in a timely manner increases the uncertainty of the production plan, such as excessive revisions to the plan, increased costs of remedial measures, overtime costs and expedited transportation costs, etc.