Example methods disclosed herein include associating a first data pattern obtained from a first sequence of watermarks detected by a first media monitor at a first time with a first transmission of first media when the first sequence of watermarks include a first identifier associated with the first media. Disclosed example methods also include associating a second data pattern obtained from a second sequence of watermarks detected by the first media monitor at a second time with a second transmission of the first media when the second sequence of watermarks include the first identifier associated with the first media. Disclosed example methods further include comparing a third data pattern obtained from a third sequence of watermarks detected by a second media monitor with the first and second data patterns to determine whether the second media monitor monitored the first transmission or the second transmission of the first media.