Facebook overestimates video viewing figures to advertisers' anger

In some cases, statistics for viewing figures were inflated by as much as 80%.

The error by the Facebook metric centred around its average viewing time figures, which did not include those who viewed the ad for three seconds or less. This process allowed the network to boast considerably higher statistics, in the process misleading advertisers about the number of people their product was reaching.

Facebook said that they have corrected the error in a statement.

"We recently discovered an error in the way we calculate one of our video metrics," Facebook said. "This error has been fixed, it did not impact billing, and we have notified our partners both through our product dashboards and via sales and publisher outreach."

WSJ quoted one of Facebook's advertising partners Publicis as saying the incident was "unacceptable".

"This once again illuminates the absolute need to have 3rd party tagging and verification on Facebook’s platform," the note from Publicis read. "Two years of reporting inflated performance numbers is unacceptable."

Advertising revenue makes up the vast majority of Facebook's income, with its second quarter this year showing a 63% increase compared with the same period last year, increasing to $6.2bn.