Facebook massively miscalculated video viewing figures for two years

The social networking giant has managed to attract the ire of advertisers after it revealed that it overestimated video viewing figures for two years. A flaw in the tool used to measure the number of views meant that figures relating to video viewing times were inflated by between 60 and 80 percent.

Just how long people spend watching videos is important information for advertisers, but Facebook managed to miscalculate average viewing times by ignoring views lasting under three seconds. With so much of Facebook's incoming revenue derived from advertising, and the importance the company places on video, the snafu is an embarrassing one that advertisers will take some time to forget.

While Facebook says the miscalculation in no way affects advertisers' bills, it does still mean that the social network has been providing incorrect -- and therefore far less useful -- data to its ad partners. The company issued a statement saying: "We recently discovered an error in the way we calculate one of our video metric. 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. We also renamed the metric to make it clearer what we measure. This metric is one of many our partners use to assess their video campaigns".

Facebook also made an announcement on its Advertiser Help Center explaining a little about the problem:

NOTE: We recently discovered a discrepancy between the definition of Average Duration of Video Viewed and its calculation.

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".

Facebook advises that two new metrics will now be used to "help you better evaluate your ad performance":

Video Average Watch Time: the total watch time for your video, divided by the total number of video plays. This includes plays that start automatically and on click. This will replace the Average Duration of Video Viewed metric.

Video Percentage Watched: reflects the percentage of your video somebody watches per session, averaged across all sessions of your video where the video auto-played or was clicked to play. This will replace the Average % Video Viewed metric.

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