A systematic increase or decrease in the mean demand of a time series is referred to as a seasonal pattern. random variation. a trend. a cyclical pattern. Demand forecasts are generally more accurate for an individual product than a product family. when a firm focuses only on internal sources of information and not external sources of information. when there are fewer product choices. for a longer term than a shorter term. Which of the following costs is least likely to decrease following quality improvements? Training costs Rework costs Scrap costs Warranty costs