If you have been relying heavily on Facebook’s average duration of video viewed metric, you’ve likely been using some inaccurate stats. Facebook has officially announced that the metric has bee over-reported due to a miscalculation. Along with the announcement came an apology for the misinformation from David Fisher, VP of Advertising & Global operations at Facebook.
In a lengthy Facebook post, Mr. Fischer chalked the error up to do an invalid equation that generated the metric. The metric should have been calculated by diving the total time spent watching a video by the total number of people that played the video. Instead it used a formula that divided the total time spent watching a video divided by the number of “views” of a video. Basically, instead of dividing by number of plays, it was divided by the number of “views” (when the video was played for three or more seconds). This error has now been fixed.
Of course this math led to over-inflated stats for the “average duration of video viewed” metric. Thankfully, this math error had no impact on any other reporting and it has had no impact on numbers that Facebook has shared in the past. For marketers, if you have been relying on the average duration of video viewed metric, you may brace yourself as lower numbers are imminent. Thankfully, all other metrics are unscathed.
For the apology and explanation behind the error, please see the full Facebook post from Mr. Fisher.