A family of related products or items organized at various levels. For example, a certain brand of toothpaste may come in several flavors, and each flavor may be packaged in several tube sizes. The forecaster’s task is to project the volume of demand for each stock-keeping unit (sku) – a package of a specific flavor – as well as total demand for each flavor and overall demand for the brand. The forecaster should reconcile the forecasts made at each level of the hierarchy.  See reconciling forecasts.