An example includes a segment collector to: access impression records indicative of media access segments, the media access segments including start times and end times corresponding to media accessed by a panelist; and determine ones of the impression records that include a watermark corresponding to a first media platform presenting the media; a segment classifier to convert a first one of the impression records including the watermark to a converted impression record; and combine the converted impression record corresponding to the first media platform and a second impression record corresponding to a second media platform; and a media creditor to generate audience measurement metrics based on the combined impression records.