Abstract: A set of preliminary search results is retrieved based on a search query, the set of search results including a plurality of pay-per-click listings. A normalized click-through rate is calculated for each pay-per-click listing in the set of preliminary search results, the normalized click-through rate being based on an actual click-through rate that is adjusted according to one or more positions in which the pay-per-click listing was previously provided in one or more sets of final search results. The plurality of pay-per-click listings is ordered based on the calculated normalized click-through rates.

Abstract: At least one listing is retrieved based on a search query, the query including at least one parameter associated with an element of a hierarchical index A determination of a normalized click-through rate for each of the at least one listings is made, the normalized click-through rate for a listing being based on a click-through rate for the listing that is adjusted according to one or more positions in which the listing has been displayed in each of a plurality of sets of search results. A determination is made of a position for the at least one listing in a set of search results based at least in part on an aggregation of the aggregate normalized click-through rates associated with at least one level of a hierarchical index.

Abstract: A plurality of pay-per-click listings is retrieved based on a search query. For each pay-per-click listing, a rank value is calculated that is based at least in part on a performance score and a maximum bid, thereby generating a calculated rank value. The plurality of pay-per-click listings is ordered based at least in part on the calculated rank value. A cost is determined associated with each of the plurality of pay-per-click listings.