Selecting score improvements

Abstract

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for selecting score improvements. In one aspect, a method includes obtaining search query data, each search query being associated user selection data that identifies which search results were selected by users; obtaining a plurality of score improvement lists, each score improvement list being an ordered list of adjusters, wherein the adjusters are serially applied to initial scores of a group of search results to determine a final scoring of the search results; testing the plurality of score improvement lists comprising: iteratively selecting pairs of score improvement lists from a pool of score improvement lists, and determining, for each pair of score improvement lists, a winning score improvement list and a losing score improvement list based on the search query data, repeating testing until ending criteria are reached; and selecting one or more score improvement lists.