Facebook has been accused of inflating its ad reach by millions compared to US census data, once again bringing into question the metrics that Facebook uses to calculate its offering.

The social network’s Ads Manager claims to have potential a potential reach of 41m 18 to 24-year olds and 60m 25 to 34-year olds in the US. However, Pivotal Research analyst Brian Weiser has taken aim at these figures because census data shows there are only 31m and 45m in each age bracket respectively.

“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,” said Wieser, according to Reuters.

Facebook fired back at the claims in a statement, saying that its audience estimates did not match census data because the numbers “are designed to estimate how many people in a given area are eligible to see an add a business might run. They are not designed to match population or census estimates.”

The statement from the social network suggests that its estimates also account for those visiting the US at any given time, due to the company’s use of location data. In addition, age data on Facebook may vary from census data because not everybody on Facebook uses their real age.

The latest accusations follow the misreporting issues that rocked Facebook last year, and led to it agreeing to be audited by the Media Rating Council (MRC) earlier this year.