Despite the importance of identifying the hierarchy of product attributes that drive judgment and choice, the many available methods remain limited regarding their convergent validity and test-retest reliability. To increase the validity and reliability of attribute-importance measurement, we focus on the central antecedent of the importance of product attributes in judgment and choice: consumers' valuation curve of an attribute - the idiosyncratic valuation of an attribute at different attribute levels relative to consumers' reference points. We propose two new attribute-importance measures that reflect the determinance and the relevance of an attribute respectively, and show that accounting for the effects of reference points increases the predictive validity of attribute-determinance measures