Facebook will provide credit to a small proportion of advertisers it overcharged for the number of click-throughs reported on mobile web video advertising, AdNews can reveal.
The social media giant says the glitch is relatively minor in terms of scale and cost, but, significantly, it represents the first time Facebook’s misreporting has had a material effect on billings.
After a standard review, the social media network discovered it had inflated the number paid click throughs on its mobile web video carousel ad function.
The glitch, which affects 0.04% of Facebook ad impressions, had overcharged advertisers a median amount of $10 over a year. It does not affect mobile app or desktop, the two main interfaces that users view Facebook.
What went wrong
When users click on a video carousel ad unit, the video expands to full screen viewing. At the bottom of the video there is a link click ad that users can click on, redirecting them to an advertiser’s website (see below).
Advertisers can choose to buy on the basis of link click ads rather than impressions. However, the glitch meant that for users on mobile web, Facebook was incorrectly attributing carousel video views as link clicks. This bug has affected advertisers billed link clicks since March 2016.
AdNews understands Facebook has reached out to media agency groups in Australia to inform them they are reviewing local clients who may be affected.
Confidence in the robustness of Facebook’s metrics was questioned last August when it emerged video views had been over-reported by as much as 80% for two years.
Facebook carried out a comprehensive review and found several more cases of metrics misreporting affecting video views, the time spent on Instant Articles, organic reach counts discrepancies in video completions and app referrals.
The social media network has taken measures it believes will offer more transparency “clarity and confidence” in its metrics, including opening up its metrics to a level of third party verification. Facebook tells AdNews it operates a policy to report any cases of misreporting it comes across as soon as it is discovered.
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