6. The method of claim 5 , wherein the predicting the average position comprises: calculating a historical average position in which the individual advertisement is displayed in other search return lists generated by the search engine in response to other search queries that include the keyword; and applying one or more regression models to the historical average position.
5. The method of claim 2 , wherein the evaluating further comprises predicting an average position in which an individual advertisement from an individual keyword-advertiser relationship will be displayed in a search return list generated by a search engine in response to a search query which includes the keyword, the search return list being generated during the period of time.