From a more qualitative perspective, we clearly saw the benefit of the filtering mechanism in the example in Section 3.3 (Tables 2 and 3): when a gen-eration component is used to describe the contents of clusters, the inclusion of author-specific words is uninformative and even confusing.
this gives an overall measure of how well the cluster represents the newsgroup, taking into account the 'correctness' of the cluster (precision) and how much of the newsgroup it accounts for (recall the F-score is then calculated as have been calculated, we choose for each cluster the best newsgroup assignment, i.e.