Methods and systems for predicting out-of-stock occurrences and for assigning root causes to out-of-stock occurrences are described. In one implementation, inventory data and point of sale data are collected. An expected lost sales value is determined. A true demand is determined based on the point-of-sale data and the expected lost sales value. A probability of an out-of-stock occurrence is determined based on the inventory data. In another implementation, an out-of-stock occurrence is identified. The out-of-stock occurrence is classified, and one or more root causes are assigned to the out-of-stock occurrence.