14. The system of claim 13 , the instructions further comprising a search engine module configured to process a query to identify item listings, among the plurality of item listings, that satisfy the query.
14. The system of claim 13 , the instructions further comprising a search engine module configured to process a query to identify item listings, among the plurality of item listings, that satisfy the query. 15. The system of claim 14 , the instructions further comprising a ranking score module configured to determine, for each of the item listings that satisfies the query, a ranking score based, a least in part, on the weighted sums of the predicted listing quality score and the observed listing quality score for the item listing.