Senior analyst at Pivotal Research, Brian Wieser, has issued a report pointing out that Facebook has been claiming to reach more people than U.S. Census data says exist. Facebook has been promoting itself as reaching 41 million adults between the ages of 18 and 24.

However, Census data says there are just 31 million. And Facebook also says it reaches 60 million people between the ages of 25 and 34, while the U.S. Census estimates that total to be 35 million. Wieser says he began his own inquiry into the data situation after Australia’s AdNews found discrepancies between Facebook claims and Census data in that country. A Facebook spokesperson says the estimates the platform uses “are not designed to match population or census estimates.” Instead they are “designed to estimate how many people in a given area are eligible to see an ad a business might run.”

WHY THIS MATTERS: However it tries to justify use of the faulty numbers, Facebook will not ingratiate itself to advertisers for offering up misleading data. Wieser told The New York Times, “The buyers and marketers I talked to were unaware of this and they are using [the Facebook data] for planning purposes. Buyers are still going to buy from them and plan for them, but this is something that doesn’t need to be an error and puts every other metric they might provide into question.”