According to Korolova, she discovered that despite her turning off her location tracking, Facebook still managed to serve up ads based on her location. To Facebook’s credit, they never really hid how they went about collecting your location data, although it wasn’t necessarily in the most obvious of places as Korolova found more information in a page called “How Facebook ads work”, where Facebook claims that it gathers data from other sources such as where you use your internet and where you use your phone.
Facebook details this further to advertisers where they say that they rely on other features like your IP address, WiFi, and Bluetooth data. In response to Korolova’s article and paper, Facebook released a statement to Gizmodo which more or less confirms it, going as far as claiming that there is no way for users to completely opt out of using location for ads entirely.
According to the statement, “There is no way for people to opt out of using location for ads entirely. We use city and zip level location which we collect from IP addresses and other information such as check-ins and current city from your profile to ensure we are providing people with a good service—from ensuring they see Facebook in the right language, to making sure that they are shown nearby events and ads for businesses that are local to them.”