10. The non-transitory computer-readable memory device of claim 8 , where the one or more instructions to select the particular subsequent search query further cause the one or more processors to: select a particular cluster, of the first cluster or the different, second cluster; and select one of the refinements, from the selected particular cluster, that was received a quantity of times after the particular search query and identified as a refinement of the particular search query, based on the quantity of times being greater than a quantity of times that other one of the refinements, of the selected particular cluster, were received after the particular search query and identified as refinements of the particular search query.
8. A non-transitory computer-readable memory device storing instructions, the instructions comprising: one or more instructions which, when executed by one or more processors, cause the one or more processors to: identify a plurality of subsequent search queries that were received after a particular search query, as refinements of the particular search query; identify a first set of documents that is associated with a first subsequent search query, of the plurality of subsequent search queries; identify a second set of documents that is associated with a second subsequent search query, of the plurality of subsequent search queries; generate a first term vector for the first subsequent search query based on the identified first set of documents, and a second term vector for the second subsequent search query based on the identified second set of documents; cluster, based on the generated first term vector and the generated second term vector, the first subsequent search query into a first cluster and the second subsequent search query into a different, second cluster; select a particular subsequent search query from one or more of the first cluster or the different, second cluster; receive an indication that a client device has submitted a search query that includes the particular search query; and provide, to the client device, the selected particular subsequent search query from the one or more of the first cluster or the different, second cluster, as a refinement of the search query submitted by the client device.