For plural categorical values of a first attribute, more relevant categorical values of a second attribute are selected from among candidate categorical values of the second attribute, where the selecting uses a relevance determination process that considers frequencies of occurrence of respective pairs of the categorical values of the first and second attributes. A visualization that includes groups of cells corresponding to the respective pairs of categorical values of the first and second attributes is generated. At least one of the groups includes cells assigned visual indicators based on values of a third attribute.