1. A method to determine audience duplication in cross-media campaigns, the method comprising: determining a first duplicated audience reach between a total television audience and an internet publisher audience for a demographic group, the total television audience representative of audience members across a plurality of television networks, and the internet publisher audience representative of audience members across one of a plurality of internet publishers; determining a second duplicated audience reach between the total television audience and the internet publisher audience for a media campaign based on the first duplicated audience reach; determining a third duplicated audience reach between a television network audience and the internet publisher audience for the media campaign based on the second duplicated audience reach, the television network audience representative of audience members exposed to the media campaign via one of the plurality of television networks; determining a fourth duplicated audience reach between the total television audience and a total internet audience for the demographic group, the total internet audience representative of audience members exposed to the media campaign via the plurality of internet publishers, the fourth duplicated audience reach is determined based on a television-to-internet universe based exposure correlation value (ρ (TV — AnyInternet) ) according to: ρ ( TV_AnyInternet ) = { ρ ( CPH ) ⁢ p 1 ⁢ ( CPH ) ⁢ p 2 ⁢ ( CPH ) ⁡ [ 1 - p 1 ⁢ ( TV ) ] ⁡ [ 1 - p 2 ⁢ ( Online ) ] [ 1 - p 1 ⁢ ( CPH ) ] ⁡ [ 1 - p 2 ⁢ ( CPH ) ] ⁢ p 1 ⁢ ( TV ) ⁢ p 2 ⁢ ( Online ) p 1 ⁢ ( CPH ) ≤ p 1 ⁢ ( TV ) p 2 ⁢ ( CPH ) ≤ p 2 ⁢ ( Online ) ρ ( CPH ) ⁢ p 1 ⁢ ( CPH ) ⁡ [ 1 - p 2 ⁢ ( CPH ) ] ⁡ [ 1 - p 1 ⁢ ( TV ) ] ⁢ p 2 ⁢ ( Online ) [ 1 - p 1 ⁢ ( CPH ) ] ⁢ p 2 ⁢ ( CPH ) ⁢ p 1 ⁢ ( TV ) ⁡ [ 1 - p 2 ⁢ ( Online ) ] p 1 ⁢ ( CPH ) ≤ p 1 ⁢ ( TV ) p 2 ⁢ ( CPH ) > p 2 ⁢ ( Online ) ρ ( CPH ) ⁢ [ 1 - p 1 ⁢ ( CPH ) ] ⁢ p 2 ⁢ ( CPH ) ⁢ p 1 ⁢ ( TV ) ⁡ [ 1 - p 2 ⁢ ( Online ) ] p 1 ⁢ ( CPH ) ⁡ [ 1 - p 2 ⁢ ( CPH ) ] ⁡ [ 1 - p 1 ⁢ ( TV ) ] ⁢ p 2 ⁢ ( Online ) p 1 ⁢ ( CPH ) > p 1 ⁢ ( TV ) p 2 ⁢ ( CPH ) ≤ p 2 ⁢ ( Online ) ρ ( CPH ) ⁢ [ 1 - p 1 ⁢ ( CPH ) ] ⁡ [ 1 - p 2 ⁢ ( CPH ) ] ⁢ p 1 ⁢ ( TV ) ⁢ p 2 ⁢ ( Online ) p 1 ⁢ ( CPH ) ⁢ p 2 ⁢ ( CPH ) ⁡ [ 1 - p 1 ⁢ ( TV ) ] ⁡ [ 1 - p 2 ⁢ ( Online ) ] p 1 ⁢ ( CPH ) > p 1 ⁢ ( TV ) p 2 ⁢ ( CPH ) > p 2 ⁢ ( Online ) wherein the value ρ (CPH) is a cross-platform home audience universe based television-internet media exposure correlation, wherein the value p 1(CPH) is a cross-platform home audience universe based television reach, wherein the value p 2(CPH) is a cross-platform home audience universe based internet reach, wherein the value p 1(TV) is a television universe media reach, and wherein the value p 2(Online) is an internet universe media reach; and using the fourth duplicated audience reach to determine the first duplicated audience reach between the total television audience and the internet publisher audience for the demographic group.