Facebook claims its ads have the potential to reach more people than recent U.S. census data shows exist, and that's troublesome for one analyst, who thinks third-party measurement services stand to benefit. From a report: Recently, Pivotal Research Group analyst Brian Wieser was intrigued by a trade publication study in Australia that said Facebook was claiming to reach 1.7 million more 16- to 39-year olds than actually existed in the country, according to Australian census data. In reproducing the study for the U.S., Wieser said Facebook's Ads Manager claims it can potentially reach 41 million 18- to 24-year-olds, 60 million 25- to 34-year-olds, and 61 million 35- to 49-year-olds. The problem arises when Wieser pulls up U.S. Census data from a year ago, showing 31 million 18- to 24-year-olds, 45 million 25- to 34-year-olds, and 61 million 35- to 49-year-olds. The upshot: Where is Facebook getting the extra 25 million 18- to 34-year-olds that the U.S. census did not count? "Conversations with agency executives on this topic indicate to us that the gap between Facebook and census figures is not widely known," Wieser said. "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."