Wash criteria and the analytic hierarchy process

In the application of the analytic hierarchy process, a wash criterion is one where all alternatives are equally preferred with respect to that criterion. In the case where the wash criterion is a subcriterion, we address the effect of removing it from the hierarchy. Eliminating an important subcriterion may affect the importance of the criterion of which it was a part. If a wash subcriterion is eliminated, the pairwise comparisons with respect to the criteria must be reassessed. After reassessment, the overall rank order of objects may or may not be affected by excluding wash subcriteria. If the criteria are not reassessed, we argue that wash subcriteria should not be eliminated.