Did you watch NBC's "Nightly News" last week — or the "Nitely News"?

The little misspelling could make a huge difference. Advertising rates are based on ratings compiled by Nielsen Holdings, so if networks could figure out how to keep the good ratings and somehow delete the bad ratings — well, ka-ching!

That is apparently what one network was recently nabbed trying to do. "Mediaite first noticed in June that an episode of NBC News' 'Nightly News' set to air the Friday before Memorial Day (typically a slow news day) was retitled 'Nitely News.' As a result, Nielsen's automated system treated the Friday show as if it were another show entirely," the Free Beacon reported.

The deception worked: NBC's news program topped ABC's World News Tonight, which suffered from weak ratings on its properly-spelled Friday newscast.

But ABC has tried the trick before, too, the Wall Street Journal reported, airing seven episodes of Wrld New Tonite. And CBS has aired 12 episodes of Evening Nws.

Nielsen, apparently, does allow such deceptions, but they're reserved for special circumstances, like on Christmas Day or when a scheduled broadcast is moved to accommodate a special sporting event.

"If we find a network working in contrast to this agreed-upon policy, we address the issue in a direct fashion as a way to maintain fairness and balance for all of our clients and the industry as a whole," Nielsen told the Journal.

The war between the networks has been growing tighter in recent months, with NBC and ABC battling for the top spot, Mediaite reported.

Nightly News is dangerously close to losing the season to ABC in total viewers for the first time in 21 years. During the last season before David Muir became anchor (2013-14), World News Tonight lost the season by an average of more than 1 million viewers per night. Three years later, World News Tonight has closed this viewer deficit gap and is currently leading the season for the first time in 21 years since Peter Jennings was anchor. ...

According to research available at the time of publishing, had Nightly News‘ ratings average been based on the full five days of last week — as was ABC’s — and did not retitle Friday’s program — then World News Tonight would have won the week by roughly 37,000 viewers head-to-head. But the shrewd manner by which NBC retitled Friday’s show dropped their lowest-rated day of the average which pulled NBC’s program ahead of ABC’s by 264,000. Oddly, had ABC also retitled their Friday show (dropping the least viewed day out of their weekly average) NBC would have also won the week. Got it? ...

This isn’t the first time NBC has displayed aggressive tactics. In 2015 they secretly aired Nightly News overnight in several markets to increase viewership and count two viewership numbers in these cities instead of one. And a cursory search of ‘Nitely News‘ suggests that this isn’t the first time that ‘Nitely News‘ has boosted their ratings.