10. A method of expanding a search, the method comprising: calculating a diversity index for a plurality of query terms included in a plurality of other queries associated with a query, the diversity index being a measure of diversity among the plurality of query terms, the diversity relating to differences among the plurality of query terms; comparing the diversity index to a threshold value; and expanding the query with one or more of the plurality of query terms based on the comparison.
12. The method of claim 10 , wherein the diversity index is a Simpson's diversity index.