Facebook is going through a bit of a rough patch with its PR right now. Following criticism over how it filters news during the US presidential candidacy race, it’s now being blamed for influencing the recent US election.

Away from political soap operas, Facebook has another problem. Last month, the social giant admitted it had been overestimating the number of views its video ads generated. And now Facebook is telling us it has discovered more miscalculations in the numbers it provides advertisers.


Facebook’s metric errors

Rather than put our own spin on things, here’s what Facebook has to say on the issue:


“We’ve uncovered a bug in Page Insights. On one of our Pages dashboards, one summary number showing 7-day or 28-day organic page reach was miscalculated as a simple sum of daily reach instead of de-duplicating repeat visitors over those periods (see red circle in screenshot below).”

“However, the vast majority of reach data in the Page Insights dashboard (marked green in screenshots below) was unaffected, including all the graphs, daily and historical reach, per-post reach, exported and API reach data, and all data on the Reach tab.”


“The de-duplicated 7-day summary in the overview dashboard will be 33% lower on average and 28-day will be 55% lower; data in other fields is unaffected. This bug has been live since May; we will be fixing this in the next few weeks. It does not affect paid reach.” Facebook Business


As you can see, it’s that reach metric circled in red that’s been causing problems. Everything circled in green has been deemed accurate by Facebook and the following data on reach has been given the OK too:


Facebook also says there have been errors on the following metrics:


  • Video: Up to 35% overestimation of users who watch video ads in full
  • Instant articles: Time spent on Instant Articles was overestimated by 7-8% on average since August last year – the issue is now fixed.
  • App referrals: Overestimated by around 6%.
  • Interest Lists: Overestimated number of followers by roughly 5%.


It’s important to note that no advertisers have been overcharged due to the errors. The issue is over the reliability of information over ad performance.


Facebook working to fix issues

None of this will come as welcome news to advertisers, of course. However, Facebook says is has either fixed or is in the process of fixing each of the bugs. What’s interesting is how public Facebook is being about all of this. We’ve all questioned the accuracy of AdWords data but it seems Google is either squeaky clean or very tight-lipped about any errors.

Going back to Facebook, one of its biggest strengths (from the advertiser’s perspective) is it works with a ton of third-party data firms. Which means we’re not relying on Facebook numbers alone. Perhaps this is why the social giant is being so open about the bugs it has detected – it’s better to fess up now than let the news come out from somewhere else.

Either way, we can only speculate on details other than the numbers Facebook is giving us. In the meantime, we’ll keep you updated on any new developments so keep an eye out for new blog articles and social media posts.


Have you been affected by any of Facebook’s miscalculations? Let us know your experiences and be sure to give us a shout if you need any advice.