An example metrics manager determines a first audience reach for a television audience, the television audience representative of audience members exposed to a media campaign via television media delivery, determine a second audience reach for a digital audience, the digital audience representative of audience members exposed to the media campaign via digital media delivery. An example deduplicator obtains an overlap multiplier based on the media campaign, the overlap multiplier is a ratio of (1) a product of a panel duplication reach and a did-not-view reach and (2) a product of a television panel reach and a digital panel reach, and determine a duplication factor for the media campaign based on the first audience reach, the second audience reach and the overlap multiplier. An example audience manager determines a total audience for the media campaign based on the first audience reach, the second audience reach and the duplication factor.