1. A method comprising: identifying, by a system having a processor, concepts in a plurality of clusters of documents; identifying, by the system for a first one of the plurality of clusters, groups of connected concepts of the first cluster; computing, by the system, at least one interestingness measure for each of the groups of connected concepts in the first cluster; and deriving, by the system, an interestingness measure for the first cluster based on the interestingness measures for the corresponding groups of connected concepts.