“One of the signals we use is how people interact with articles,” Lyons said in a follow-up email. “For example, if someone previously gave us feedback that an article was false and the article was confirmed false by a fact-checker, then we might weight that person’s future false-news feedback more than someone who indiscriminately provides false-news feedback on lots of articles, including ones that end up being rated as true.” The score is one signal among many that the company feeds into more algorithms.

Source : Facebook is rating the trustworthiness of its users on a scale from zero to 1 – The Washington Post