(Thomson Reuters)

For the last couple years, Facebook has talked about the massive growth of video on its platform.

It turns out Facebook may have exaggerated a key metric — the average amount of time viewers spent watching each video — to advertisers by as much as 80%, according to The Wall Street Journal.

A few weeks ago, Facebook reportedly notified advertisers that it had accidentally been excluding videos that users watched for less than 3 seconds from its "Average Duration of Video Viewed" measurement.

It's introducing a new measurement, called "Average Watch Time," that will include all videos, regardless of how long people watched them.

Publicis Media, which buys ads for clients, later heard from Facebook that the original measurement was probably exaggerated by 60% to 80%, according to a letter Publicis sent its clients, which The Journal saw.

The letter also suggested Publicis was upset with the way Facebook was spinning the mistake by introducing a new metric: "Essentially, they’re coming up with new names for what they were meant to measure in the first place,” The Journal reports Publicis saying.

A Facebook spokesperson said the error has been fixed and did not affect billing.

You can read the full story over at The Wall Street Journal»

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