27. The system of claim 25 , wherein the system further comprises: a data communication network coupled to the server device; and a data processing device programmed to transmit the search query over the data communication network to the server device.
27. The system of claim 25 , wherein the system further comprises: a data communication network coupled to the server device; and a data processing device programmed to transmit the search query over the data communication network to the server device. 31. The system of claim 27 , wherein estimating the breadth of the search query comprises estimating the breadth of the search query based on differences in relevances of documents in the result set.