Filtering system for providing personalized information in the absence of negative data

Systems and methods are provided for personalizing advertising for a user. In accordance with certain implementations, information is accessed indicating which documents were selected by a user and which documents were not selected by a user. At least one positive word vector is generated using words contained in at least one of the selected documents, and at least one negative word vector is generated using words contained in at least one of the unselected documents. Document word vectors are generated, and a document rank order is established based on a vector space relationship analysis. Categories associated with the documents are ranked based on the document rank order, and the ranked categories are sent to an ad server. Advertising material associated with the ranked categories may then be received from the ad server in a selected context.