The Friendship Paradox and Systematic Biases in Perceptions and Social Norms

The friendship paradox (first noted by Feld in 1991) refers to the fact that, on average, people have strictly fewer friends than their friends have. I show that this oversampling of more popular people can lead people to perceive more engagement than exists in the overall population. This feeds back to amplify engagement in behaviors that involve complementarities. Also, people with the greatest proclivity for a behavior choose to interact the most, leading to further feedback and amplification. These results are consistent with studies finding overestimation of peer consumption of alcohol, cigarettes, and drugs and with resulting high levels of drug and alcohol consumption.