Facebook has been overestimating the time users have spent watching videos over the last two years, the company has admitted to advertisers.
The error could possibly affect marketing spend of ads on the social networking platform. The measurement was artificially increased as it only counted videos as viewed if they have been watched for more than three seconds. This did not take into account shorter viewings, according to a posting by Facebook on its Business page.
"We had previously *defined* the Average Duration of Video Viewed as "total time spent watching a video divided by the total number of people who have played the video." But we erroneously had *calculated* the Average Duration of Video Viewed as the total time spent watching a video divided by *only* the number of people who have viewed a video for three or more seconds," the company said on its blog, first published a few weeks ago.
But advertisers asked for further clarification of the matter. According to a report from the Wall Street Journal yesterday, the overestimation was between 60% and 80%. The publication received a letter that Facebook sent to an advertiser which stated the figures. Facebook's shares fell more than 1.5% following publication of the report.
In a statement to the media, Facebook said that the error "has been fixed, it did not impact billing, and we have notified many of our partners both through our product dashboards and via sales and publisher outreach".
Facebook has now implemented a new metric called "Average Watch Time", which now measure video viewings of any duration and not just ones for longer than three seconds.
But ad company Publicis said in a memo to clients (and reported in the WSJ) that "in an effort to distance themselves from the incorrect metrics, Facebook is deprecating [the old metrics] and introducing new' metrics in September. Essentially, they're coming up with new names for what they were meant to measure in the first place".
