Research by the Social Cognitive Network Academic Research Centre (SCNARC), at Rensselaer Polytechnic Institute, also showed that people tend to move in groups of friends, and that two people chosen at random at a specific event (like a concert or at a particular store) are unlikely to be friends.
"The ramifications are extremely important because if we assume that people are moving randomly, we are wrong and, therefore, we will not be prepared for what people actually do," said Boleslaw Szymanski, director of SCNARC and professor of computer science at Rensselaer.
"Where you live really matters: Most of your friends are concentrated in the place where you live, and as the distance increases, this concentration rapidly drops," added Szymanski, reported the Proceedings of the 2012 IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining.
The findings also indicate that, even in the digital age, humans still form friendships based on personal interactions, said Tommy Nguyen, Rensselaer graduate student and member of SCNARC, according to a Rensselaer statement.
"Even though, thanks to the Internet, you can be friends with anyone on the planet, the likelihood that a person will be friends with someone in a distant location chosen at random is far lower than the likelihood that this person will be friends with someone who lives in close proximity," said Nguyen.