Discovery Communications said today (Feb. 18) it will begin reporting results for the majority of its networks' programming based on Live + 3 ratings and delivery data.

The shift covers most programming, except live shows and specials, for Discovery's U.S. networks, including Discovery Channel, TLC, Animal Planet, Investigation Discovery, Science Channel, Destination America, American Heroes Channel, Velocity, Discovery Life Channel and Discovery Family Channel.

Explaining its rationale. Discovery noted that Q4 2014 premieres across its top networks saw an average increase of 23% in P25-54 delivery when looking at Live + 3  versus Live + Same-Day results. For the year, some series premieres were up as much as 42% (TLC's Sister Wives) in Live + 3 over Live + Same Day. Other series premieres with double-digit gains last year were Discovery Channel’s Gold Rush (up 41%) and Bering Sea Gold (up 35%), and Animal Planet’s Pit Bulls and Parolees ( up 37%).

“As time-shifted viewership continues to increase, Live + Same-Day data no longer captures an accurate picture and value of our audience, and the lift from Live + 3 for many of our top programs is significant and growing,” David Leavy, chief communications officer for Discovery Communications. “As a company – and an industry – it is critical that we adapt the way we measure and report our viewership, and have a complete representation of the full audience.”

The mid-season finale of Mad Men’s final season rang up significant Nielsen advances when gauged on live + 3 basis.

While the May 25 premiere – on the Sunday night of Memorial Day weekend – delivered 1.9 million, off significantly from its sixth-season ender, the episode entitled Waterloo tallied 3.6 million viewers on live + 3 measure. That was 87% from its live/same-day performance last Sunday.

The numbers also climbed dramatically among adults 25 to 54 – up 114% to 2.04 million of those watchers from its live/same-day level – and persons 18 to 49, where it improved 116% to 1.84 million of those viewers Madison Avenue covets most.

“It comes as little surprise to see the Mad Men audience, the most upscale audience on television and some of the most elusive live-television viewers anywhere, grow by triple digits in key demographics in just three days," said AMC president Charlie Collier. "Congratulations and thank you, as a fan, to Matthew Weiner and the entire Mad Men team for a remarkable seven episodes and a mid-season finale that is as creatively bold and emotional as a Mad Men episode can be. We'll miss you Bert. Bravo.”

Collier’s reference was to the death of Sterling, Cooper, Pryce founder and proprietor Bertram Cooper, played by Robert Morse, who died during the mid-season finale and whose ghost danced and sung “The Best Things in Life are Free” before Don Draper (Jon Hamm) in the last scene.