1. A computer-implemented method comprising: receiving focus information descriptive of a search engine advertising campaign from an advertising campaign manager, the focus information comprising two or more keyword search strings, each keyword search string paired with at least one bid parameter, an importance of each keyword search string characterized by the at least one bid parameter; accessing a respective consumption history of each of a plurality of entities in a storage; identifying, at an audience selection system, a set of entities from the storage by examining each of the respective consumption histories for one or more proxy events, each proxy event comprising a keyword search matching at least one of the two or more keyword search strings described in the focus information; weighting each proxy event according to the at least one bid parameter paired with each proxy event's keyword search string; creating a training set by selecting entities from the set of entities for inclusion in a training set based on the proxy event weights of the one or more proxy events found in each entity's respective consumption history; building a behavioral model based on the training set; receiving a specified entity's consumption history; and assessing the suitability of the specific entity for selection by applying the behavioral model to the specified entity's consumption history.