A short story by Hungarian author Frigyes Karinthy first brought us the concept of “six degrees of separation”. It was later popularized in 1990 by the John Guare play and the subsequent motion picture.
In 1967, Stanley Milgram’s “small world experiment” drew on 296 volunteers and pegged the average number of people separating two indviduals at 5.2 or six “hops”.
Now, Facebook and the University of Milan have announced they have determined that the average number of people who separate any two individuals in the world is actually 4.74. Facebook’s Findings were extrapolated during the course of a month from all of Facebook’s 721 million active users, more than 10 percent of the world’s population.
“Using state-of-the-art algorithms developed at the Laboratory for
Web Algorithmics of the Università degli Studi di Milano, we were able to
approximate the number of hops between all pairs of individuals on Facebook. We
found that six degrees actually overstates the number of links between typical
pairs of users: While 99.6% of all pairs of users are connected by paths with 5
degrees (6 hops), 92% are connected by only four degrees (5 hops).
The average falls to 3 when focusing on a single country researchers found.
“And as Facebook has grown over the years, representing an ever larger fraction of the global population, it has become steadily more connected,” the network said in a blog announcing its finding. “The average distance in 2008 was 5.28 hops, while now it is 4.74.”
However, Facebook concedes differences in its study and the one conducted by Milgram.
“It is important to note that while Milgram was motivated by the same
question (how many individuals separate any two people), these numbers are not
directly comparable; his subjects only had limited knowledge of the social
network, while we have a nearly complete representation of the entire thing. Our
measurements essentially describe the shortest possible routes that his subjects
could have found.”