You may have heard statistic facts from a friend and believed them to be true. However, what happens if a friend tells you face-to-face that those facts are false. Who do you believe?
Social psychologists are familiar with this effect, sometimes called "the man who" effect.
If you hear that, "Ninety percent of the people who try this drug receive benefit from it." While your friend says, "I know a man who tried it and nothing happened!"
Somehow the face-to-face testimony of one person seems more convincing than any amount of statistics.