Facebook exaggerated video viewing times for two years

Facebook's all-encompassing video strategy could be about to take a hit after the company revealed it had overestimated the average viewing times for videos on its site for two years.

Despite confirming the error several weeks ago, a new report now claims the inflated metrics were much higher than Facebook initially let on.

Facebook confirmed the "discrepancy" last month in a post on its Advertiser Help Center: "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."

To sum it up, Facebook had been ignoring video views that lasted less than three seconds when calculating its average viewing times. As a result, the figures it provided to marketers were higher (and therefore more attractive) than they would have been if those shorter viewing times had been included. Facebook added that it was introducing a new metric to fix the issue.

Facebook did not, however, publicly elaborate on the scale of the error. Consequently, a number of ad agencies decided to press the issue, asking Facebook for more information on the so-called "discrepancy."

In response to a particular request from ad buying agency Publicis Media, Facebook provided a response in which it addressed its miscalculation in more detail. According to the Wall Street Journal -- which obtained a copy of a letter sent to clients by Publicis Media -- Facebook inflated its earlier average video viewing times by between 60-80 percent.

As of now, it is unclear whether Facebook will be impacted by the blunder. The company is downplaying the error, but the sheer size of its platform means even one botched metric could have amounted to a massive figure. Whether marketers will take this into consideration when buying Facebook ads remains to be seen. A decrease in video advertising would inevitably impede Facebook's larger video strategy.

Publicis wrote in its letter that Facebook should permit third-party verification of its ad insights. The company signed off with a statement that may indicate the wider sentiment within the marketing industry: "Two years of reporting inflated performance numbers is unacceptable."