13. The method of claim 12 , wherein obtaining an initial separation of documents into the two or more subsets comprises: separating the documents into the two or more subsets based on their quality score.
14. The method of claim 13 , wherein separating the documents into the two or more subsets comprises: placing a predetermined number of documents having higher relative quality scores in the first subset of related documents and placing documents having lower relative quality scores in a second subset of related documents.