Methods and apparatus to generating electronic mobile measurement census data are disclosed. Example disclosed methods involve, when a panelist associated with a client device is determined to be an audience member of the media on the client device, associating demographic information of the panelist with a logged impression associated with the media. The disclosed methods also include when the panelist associated with the client device is determined not to be the audience member of the media at the client device, determining probability scores for respective household members residing in a household with the panelist, the probability scores indicative of probabilities that corresponding ones of the household members are the audience member of the media at the client device, and associating demographic information of one of the household members that has a highest probability score with the logged impression associated with the media.