According to a study done by data scientists at Facebook, more of your Facebook “friends” saw what you posted than the average Facebook user realizes.
On average, each post was seen by one in three Facebook “friends,” according to an analysis of 220,000 Facebook users’ posts last June. Over the course of that month, users reached an average of 61 percent of their friends.
The study also asked Facebook users about their perceptions of how many people they reached with their posts and concluded that they “consistently underestimate” their audience size. It was carried out by a Stanford University computer scientist, Michael S. Bernstein, and three members of the company’s data science team — Eytan Bakshy, Moira Burke and Brian Karrer.