 The motivation for the measure is highly similar to the "information gain" measure introduced by Quinlan for decision tree learning.It has previously been shown that the CU for feature-based classification is the same as the mutual information between the feature variables and the class variable (Gluck & Corter, 1985; Corter & Gluck, 1992), and since this measure is much better known, we proceed here with mutual information as the measure of category "goodness".What we wish to evaluate is the overall utility of grouping the objects into a particular hierarchical categorization structure.