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.