MODIFYING RANKING DATA BASED ON DOCUMENT CHANGES

Methods, systems, and apparatus, including computer programs encoded on computer storage media for determining a weighted overall quality of result statistic for a document. One method includes receiving quality of result data for a query and a plurality of versions of a document, determining a weighted overall quality of result statistic for the document with respect to the query including weighting each version specific quality of result statistic and combining the weighted version-specific quality of result statistics, wherein each quality of result statistic is weighted by a weight determined from at least a difference between content of a reference version of the document and content of the version of the document corresponding to the version specific quality of result statistic, and storing the weighted overall quality of result statistic and data associating the query and the document with the weighted overall quality of result statistic.