The article discusses approaches to validation of multiattribute choice models. Commonly used validation techniques include cross-validation on holdout profiles and tests of consistency against current market conditions. The article proposes an alternative ratio-based approach to the predictive validation of multiattribute choice models. The approach compares the ratio of model-based choice shares with the ratio of actual unit sales, as exemplified in the choice modeling studies conducted at Hewlett-Packard Co. in the U.S.