1. A method, performed by one or more server devices, the method comprising: storing, in a memory of the one or more server devices, search query-search document associations, each search query-search document association representing a one-to-one pairing of an issued search query and a search document retrieved based on the issued search query; receiving, by one or more processors of the one or more server devices, a search query; identifying, by one or more processors of the one or more server devices, a set of search result documents using the received search query; forming, by one or more processors of the one or more server devices, a plurality of clusters of search documents, of the stored search query-search document associations, that match the identified set of search result documents; selecting, by one or more processors of the one or more server devices, at least one of the plurality of clusters; computing, by one or more processors of the one or more server devices, a centroid for each of the selected at least one of the plurality of clusters; computing, by one or more processors of the one or more server devices, a score for each unique issued search query associated with a document in the selected at least one of a plurality of clusters based on the computed centroid; formulating, by one or more processors of the one or more server devices, a search query refinement suggestion based on the compound scores; and sorting, by one or more processors of the one or more server devices, the formulated search query refinement suggestion among a group of search query refinement suggestions.