1. A method comprising: accessing a corpus stored in one or more tangible media, the corpus comprising a plurality of documents, a document comprising a plurality of words; selecting one or more words of each document as one or more keywords of the each document; clustering the documents according to the keywords to yield a plurality of clusters, each cluster corresponding to a topic; generating a statistical distribution for each cluster from a subset of the words of the documents of the each cluster to yield a plurality of statistical distributions; and modeling each topic using the statistical distribution generated for the cluster corresponding to the each topic.