Among other things, a degree is determined to which values of a feature that characterizes cases correctly predict classes to which cases belong, the degree depending on a combination of at least two factors that include: (a) uncertainty about the values that the feature will have depending on knowledge about classes to which cases belong, and (b) comparison of one or more first values of the feature that are associated with cases that belong to a first class with one or more second values of the feature associated with cases belonging to a second class.