So, remember that whole thing about Facebook mistakenly telling advertisers for two years that users were watching videos much longer than they actually were? It turns out that wasn’t the only advertising metric the social media company got wrong.

Facebook announced an update today regarding its reporting of metrics to partners and advertisers, saying that after a thorough review, conducted in the months since it first admitted overstating how long folks were watching videos on the site, it had found four other situations where it miscalculated reach.

For example, it overstated how long people spent reading Instant Articles, noting that the average time spent per article had been over-reported by 7-8% on average since August of last year.

“This was caused by a calculation error: we were calculating the average across a histogram of time spent, instead of reflecting the total time spent reading an article divided by its total views,” Facebook says, adding that the issue has been fixed.

It also overstated how many users were interacting with businesses’ Facebook Pages, as the result of a bug that has been live since May. The company says it will be fixing the issue in the next few weeks. However, the metric that measures how many people are able to see a publisher’s content on its page over the course of a week and month may shrink by an average of 33% and 55%, respectively, now that the bug has been identified.
Facebook says paid reach metrics weren’t affected, however, and neither was the metric that measures how many people see a publisher’s page on a daily basis.

This is a big deal for businesses and marketers, because they rely on how many people their content is reaching and how engaged audiences are with it, so they can decide how much money to spend on advertising. Not all mistakes were overstatements of Facebook’s reach: clients might now see the metric that measures how many people watched their whole video increase by 35% on average.

Facebook is now pledging to provide more transparency in its ad metrics reporting process, and says it will give third-party auditors like ComScore, Nielsen, and Moat more access to its data to accomplish that task.

It will also use more descriptive names to make sure metrics are clearly named, like “view content” will now be “website view of content,” and “video views” will now be “3-second video views”.

“We are committed to doing what we need to do to provide the industry with more clarity, and give the industry more confidence in our metrics,” Facebook’s advertising chief Carolyn Everson told Re/code. “We have an unwavering commitment to getting this right at any given moment, knowing that it is going to continue to evolve.”

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