CNN's headquarters in Atlanta. AP Photo/Ric Feld,File CNN conflated two statistics this week to falsely suggest that its ratings were equivalent to Fox News' during last week's coverage of President Donald Trump's inauguration.

The episode started when Trump on Tuesday congratulated Fox News on Twitter for "being number one in the inauguration ratings."

"They were many times higher than FAKE NEWS @CNN," he wrote.

CNN's public relations team responded to Trump's tweet, citing cumulative numbers from Nielsen Media Research. Cumulative numbers measure audience reach, while ratings — the statistic Trump referred to — measure the average number of people watching a given program.

"According to Nielsen cumulative numbers, 34 million people watched CNN's inauguration day coverage on television. 34 million watched Fox News," the CNN communications account said in a tweet, which was shared thousands of times and became the basis of several news stories.

On Wednesday, CNN host Chris Cuomo doubled down on the claim:

The cumulative number is technically correct. (CNN, however, rounded it. The precise numbers show Fox News with 34.4 million viewers and CNN with 34.2 million.) But it's a statistic that's rarely, if ever, used in the cable news industry, according to experts.

"It's a factual statistic, but I literally never used cumulative ratings once when I edited TVNewser," Brian Flood, a media reporter at TheWrap, told Business Insider in an email. "Not once."

Instead, it's most common for networks to provide ratings for a specific hour or program to boast about their audiences. That's the spot where Fox News handily outpaced CNN throughout Inauguration Day.

Take a look at some of the numbers from Nielsen:

Noon to 12:30 p.m. (oath of office and inaugural address):

CNN: 3.375 million total viewers

Fox News: 11.768 million total viewers

11 a.m. to 1 p.m.

CNN: 3.047 million total viewers

Fox News: 10.483 million total viewers

1 p.m. to 5 p.m.

CNN: 2.326 million total viewers

Fox News: 7.901 million total viewers

Primetime (8 p.m. to 11 p.m.)

CNN: 4.528 million total viewers

Fox News: 6.958 million total viewers

Those numbers make it clear that Fox News easily outpaced CNN in inauguration ratings, almost tripling CNN's numbers at some points in the day.

Before it engaged in a fight with Trump, CNN conceded in a press release that it came in second to Fox News.

"CNN ranked a strong #2 in cable news during the Inauguration of President Donald Trump yesterday, January 20th," the release said.

Erik Wemple, a media critic for The Washington Post, said that he had "seen some of the silliness" over the ratings and that cable news networks often engage in "puerile spats" over such things. But he said that this time, CNN perhaps escalated it further than normal.

"When there's a fact-check of the president, it moves away from the realm of standard cable-news bickering," he told Business Insider in an email.

A CNN spokesperson declined to comment.