11. The apparatus of claim 10 , the at least one storage device further comprising instructions that, when executed, cause the at least one processor to: for each of the at least one candidate entity, determine a ranking for the candidate entity based on the corresponding similarity between the first document set characterization and the second document set characterization.
10. An apparatus comprising: at least one processor; and at least one storage device comprising instructions that, when executed, cause the at least one processor to: retrieve a first set of documents from a document repository based on a query, the first set of documents having first metadata values corresponding to a plurality of metadata attributes; characterize the first set of documents based on the first metadata values to provide a first document set characterization; store the first document set characterization to provide a stored first document set characterization; determine at least one candidate entity based on the first set of documents; for each of the at least one candidate entity, retrieve a second set of documents from the document repository based on the query and the candidate entity, the second set of documents having second metadata values corresponding to the plurality of metadata attributes; for each of the at least one candidate entity, characterize the second set of documents based on the second metadata values to provide a second document set characterization; and for each of the at least one candidate entity, compare the second document set characterization with the first stored document set characterization to determine a corresponding degree of similarity between the first document set characterization and the second document set characterization.