US Patent 9224094 Systems, methods, and articles of manufacture to measure online audiences

Methods and apparatus to monitor media content at a content display site are described. An example method includes obtaining panelist data corresponding to a plurality of panelists accessing web pages at measured locations, classifying the panelist data according to demographic information of the panelists, generating a virtual panel based on an estimate of web page access at unmeasured locations, and classifying page view data associated with the unmeasured locations based on data corresponding to the virtual panel.