Nielsen’s season-to-date data includes seven days of delayed viewing, and it is there where Mr. Colbert has made up tremendous ground on Mr. Fallon, racking up big numbers in an area where nightly network talk shows are usually not a factor. Viewers are fine with catching up on a scripted comedy or drama a week after it originally aired, but who wants to watch Monday night’s talk show on a Friday when most of the jokes will have gone stale?
Primetime shows often depend on significant DVR and on-demand views to goose their numbers. The top-rated show in broadcast, “The Big Bang Theory,” sees its ratings jump 35 percent when seven days of delayed viewing is factored in. Advertisers examine three-day and seven-day delayed data when considering how much to pay for commercial time on a show.
But nightly talk shows are different.
In the 2012-13 season, for instance, David Letterman’s “The Late Show” only saw a 2 percent gain and Jay Leno got a 3 percent bump from seven days of delayed data, according to Nielsen.
By time Mr. Fallon took over “The Tonight Show” in 2014 those numbers rose: Mr. Fallon saw his delayed viewers rise by 11 percent.
Mr. Colbert has taken it to a new level. This season, Mr. Colbert has seen his numbers jump 18 percent thanks to delayed viewing. (Though gains this size are rare among broadcast networks, they are less so among cable late-night shows. Trevor Noah’s “The Daily Show,” for example, shows considerable gains through playback though his overall audience is much smaller.)
Since January, when Mr. Colbert started his weekly winning streak, his audience has jumped an average of 20 percent when seven days of delayed viewing numbers are factored in, according to Nielsen, a net of an additional 551,000 viewers. Mr. Fallon’s show added 212,000 viewers, a rise of 8 percent, and Jimmy Kimmel’s ABC show netted just an extra 81,000 viewers for 4 percent growth.
Mr. Colbert still trails Mr. Fallon in a significant statistic — the important 18-to-49-year-old demographic. Mr. Fallon has a rating point of 0.81 for the season compared to Mr. Colbert’s 0.58 and Mr. Kimmel’s 0.48.
But his growth in total viewers is a significant change in a late-night battle that had gone NBC’s way for a long time.
At the moment, just 22,000 viewers separate Mr. Colbert and Mr. Fallon on a nightly basis — Mr. Colbert is averaging 3.19 million viewers compared to Mr. Fallon’s 3.17 million. But by time the season-to-date delayed data through May 22 is tabulated — which will take several weeks — the gap between Mr. Colbert and Mr. Fallon will expand even further. The current numbers take into account shows only through the first week of May.
They do not include a May 9th show that will be a big one for Mr. Colbert. That’s when he hosted a “Daily Show” reunion of sorts with Jon Stewart, Samantha Bee, John Oliver, Ed Helms and Rob Corddry. Mr. Colbert had an audience of 3.78 million people that night — one of his biggest audiences since he took over.
But over the next three days, an additional 1.3 million people watched the show, bringing the total audience for the episode 5.1 million. That’s the biggest total audience for an episode of “The Late Show” since September 2015.
That week was good for the ratings for Mr. Colbert, who was perhaps buoyed by the attention he got when it became known that the Federal Communications Commission was looking into whether he violated the agency’s rules when he made an off-color joke about President Trump.
And this week hasn’t been too bad either. In addition to finding out that he was going to win the season ratings battle, Mr. Colbert also found out he was off the hook with the government. The F.C.C. concluded on Tuesday that no action will be taken against him.