Abstract: Embodiments of the present invention are directed to a search engine system, method and apparatus comprising a search engine, a participant management system, at least one storage database, a listing database and at least one feedback mechanism. The search engine accepts input data and utilizes the input data to search for information related to the search terms. Upon retrieval of relevant information, the data analysis module organizes the data related to the search terms into a search results list. To determine the placement of listings upon a search request, the data analysis module determines the probability, for each relevant listing, that the user will ultimately complete the desired action if the listing is shown, wherein the probability of action is determined by a plurality of factors. This probability is then combined with the specific CPA for the advertiser.