18. The medium of claim 17 , wherein the operations further comprise: applying the original query and the revised queries to the predictive model to obtain confidence measures for the revised queries based on the respective likelihood of success.
18. The medium of claim 17 , wherein the operations further comprise: applying the original query and the revised queries to the predictive model to obtain confidence measures for the revised queries based on the respective likelihood of success. 19. The medium of claim 18 , wherein the features include at least one from the group consisting of the original query, each word in original query, length of original query, a topic cluster of the original query, an information retrieval score for the original query, and the number of results for the original query.