1. A method for improving relevance of web searches for a query, comprising: providing a pre-existing relevance ranking of a plurality of query/uniform resource locator (URL) pairs, respective labels being associated with the plurality of query/URL pairs; computing a click relevance ranking of the plurality of query/URL pairs based upon user log data comprising user click data; and identifying and correcting mislabeled query/URL pairs in the pre-existing relevance ranking based upon the click relevance ranking.