12. The method of claim 1 , wherein determining the score comprises: determining a first count of clicks on content items that were associated with single word keywords derived from the past query that included the word; and determining a second count of clicks on content items that were associated with single word keywords derived from the past query that did not include the word.
12. The method of claim 1 , wherein determining the score comprises: determining a first count of clicks on content items that were associated with single word keywords derived from the past query that included the word; and determining a second count of clicks on content items that were associated with single word keywords derived from the past query that did not include the word. 13. The method of claim 12 , wherein determining the score further comprises determining a ratio of the first count to the second count.