22. The computer program product of claim 19 , further including instructions for associating the similarity score with a scaling factor.
22. The computer program product of claim 19 , further including instructions for associating the similarity score with a scaling factor. 24. The computer program product of claim 22 , wherein the instructions for assigning the popularity score to each of the set of placed content includes instructions for multiplying the scaling factor, the respective click through rate and the respective bid value.