A method for the placement of advertisements on a page to optimize the occurrence of an event associated with such advertisements. The advertisements might include, for instance, advertisements on a webpage, and the event would include a user clicking on an advertisement. Data regarding the past performance of the advertisements is stored and updated as new data is received. A user requests a page from a server associated with the system. The server uses the performance data to derive a prioritized arrangement of the advertisements on the page. The server performs a calculation regarding the likelihood that an event will occur for a given advertisement displayed to a user. The advertisements are arranged according to this calculation and returned to the user on the requested page. The likelihood can also be multiplied by a weighting factor and the advertisements arranged according to this product.