Did Facebook Fudge Its Audience Reach by 25 Million People?

Facebook is an advertising behemoth, combining with Google to account for 85 percent of all growth in online advertising. But even the social network isn’t able to reach 25 million more people than the U.S. census lists, according to one skeptical analyst.

Facebook’s ad data caught the eye of Brian Wieser, an analyst with Pivotal Research Group. In a now widely publicized memo that he sent to clients on Tuesday, he noted Facebook’s ad program said the site can reach 41 million 18-to-24 year-olds and 60 million 25-to-34 year olds in the U.S. The red flag for Wieser? The U.S. Census shows there’s only 31 million 18-to-24 year olds and 45 million 25-to-34 year olds in the country — making for a drastic 25 million person discrepancy.

Wieser said this could be an issue for the social network moving forward, just as it starts to establish itself as a destination for original content.

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“Conversations with agency executives on this topic indicate to us that the gap between Facebook and census figures is not widely known,” said Wieser in his note. “While Facebook’s measurement issues won’t necessarily deter advertisers from spending money with Facebook, they will help traditional TV sellers justify existing budget shares and could restrain Facebook’s growth in video ad sales on the margins.”

But according to Facebook, the gap is simply a misunderstanding.

“Reach estimations are based on a number of factors, including Facebook user behaviors, user demographics, and location data from devices,” a Facebook spokesperson told TheWrap. “They are designed to estimate how many people in a given area are eligible to see an ad a business might run. They are not designed to match population or census estimates.”

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In layman terms: Facebook’s numbers can account for more than simply U.S. citizens — it can also include visitors or even undocumented individuals in the region. But does that really account for the whopping 25 million discrepancy?

The Facebook spokesperson added its ad program is an “estimator and campaign planning tool,” not specifically used to bill its clients. Facebook’s advertising partners may be swayed to use the platform differently, if they misread the data, but they’re not being charged for it.

Another factor that may have contributed to the mixup: Users self-report their age on Facebook, unlike the U.S. Census.