An example apparatus includes a data parser to extract an identifier and a cookie identifier from a message received at a first server of a first Internet domain from a client device, the cookie identifier associated with the first Internet domain, the identifier identifying at least one of the client device or a user of the client device to a second server in a second Internet domain outside the first Internet domain, a memory to store the identifier in association with the cookie identifier in an identifier-to-cookie map, a processor to associate demographic information corresponding to the identifier with an impression logged at the first server in association with the cookie identifier, the associating based on accessing the memory to identify that the cookie map stores the identifier with the cookie identifier, and a report generator to send the demographic information to the second server.