METHODS AND APPARATUS TO CORRELATE CENSUS MEASUREMENT DATA WITH PANEL DATA

Methods, apparatus, systems and articles of manufacture are disclosed to correlate census measurement data with panel data. An example method disclosed herein includes instructing, via a first computing device of a monitoring entity, a media provider to embed a tag in media, the tag to cause a device accessing the media to send a message to the monitoring entity when the media is accessed by the device, the message to identify a geographic location of the device. The example method also includes accessing the message with a second computing device of the monitoring entity. The example method also includes identifying, with the second computing device of the monitoring entity, a panelist identifier based on the geographic location of the device. The example method also includes associating media identifying information included in the message with panelist data associated with the panelist identifier.