According to some data brokers, I’m a married woman in her mid-50s with a master’s degree earning enough money to make a solid down payment on a nice townhouse in New York City. Ad buyers who purchase data blindly will be sad to find out that I’m not a fancy lady; I’m just a millennial dude who relies on ad tech swag for a third of my wardrobe.

Data aggregators collect so much information on so many people that their predictions are bound to misfire periodically. But according to a May 2018 survey conducted by Lotame, most US marketers have confidence in the third-party data they purchase.

About two-thirds of respondents were somewhat confident in the demographic data they buy. However, just one-fifth were very confident in this data.

The confidence marketers have in demographic data indicates that they believe it has value, but they realize it is far from foolproof. The same survey found that 25% of marketers would pay 10% or more for their data if it was higher quality. The most common demographic data that marketers purchase is information about consumers' ages. Three-fourths of the surveyed marketers said they use that data in their ad campaigns.