Facebook has overestimated how
much video people have watched
for the last two years, the firm has admitted. One advertiser suggested that, in
some cases, video viewing statistics
had been overestimated by up to
80%. Facebook's analytics are an important
tool for advertisers, who use them to
work out how much of their video
content is being watched. The social network said the error had
been fixed and had not changed how
much advertisers paid the site. 'Unacceptable' behaviour The error affected a Facebook metric
called "average duration of video
viewed", which was supposed to tell
publishers for how long, on average,
people had watched a video. However, the metric did not include
viewers who had watched for less
than three seconds in the count. Discounting the shorter views -
including people who had ignored a
video in their news feed - inflated the
average viewing times for each video. In a statement, Facebook said: "We
recently discovered an error in the
way we calculate one of our video
metrics. "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," it added. The video-watching metric has now
been renamed to more accurately
reflect what it measures, the company
said. The metric is now called "average
watch time" and Facebook started
using this to gather statistics on video
consumption late last month. The statement also said the video-
viewing metric was one among many
that ad firms use to work out if their
content is being watched. The Wall Street Journal quoted ad-
buying firm Publicis as saying that
Facebook's misreporting was
"unacceptable". Publicis said it showed the need for
third-party verification of statistics
gathered by Facebook. The social network has previously been criticised for counting a video as being "viewed" after three
seconds.