10. The method of claim 1 , comprising: computing a distribution of labels in the pre-existing relevance ranking; and relabeling a label associated with the query/URL pairs in the click relevance ranking according to the distribution of labels in the pre-existing relevance ranking, the labels decreasing with respect to click relevance.
10. The method of claim 1 , comprising: computing a distribution of labels in the pre-existing relevance ranking; and relabeling a label associated with the query/URL pairs in the click relevance ranking according to the distribution of labels in the pre-existing relevance ranking, the labels decreasing with respect to click relevance. 11. The method of claim 10 , comprising: increasing a value of the label associated with a most relevant query/URL pair when the click rate exceeds a specified threshold.