Expert Commentary

Structural diversity in social contagion: Studying Facebook

2012 study in Proceedings of the National Academy of Sciences on the mechanisms that explain people joining and engaging with Facebook.

The social networking site Facebook is fast approaching 1 billion users, but there are still 6 billion people who have not joined the site and only about 360 million of Facebook’s 860 million registered users visit the site at least six days a week. Research has found that 20% to 30% of those on Facebook are “power users” who are much more active on the site than the average user. Who is likely to join Facebook and actively engage on the site once they’ve joined?

A 2012 study by Cornell University and Facebook published in the Proceedings of the National Academy of Sciences, “Structural Diversity in Social Contagion,” identifies Facebook recruitment and engagement patterns by examining the interconnectedness of a user’s friends on Facebook both before and after that person joins. The researchers studied approximately 10 million Facebook users who signed up during 2010 and had cultivated friend “neighborhoods” consisting of 10, 20, 30, 40, or 50 friends one week after registration and who were actively engaged on the site three months after joining.

The study’s findings include:

  • A person is much more likely to join Facebook if that person has friends on Facebook who do not know each other — a structurally diverse network — than if that person’s friends are all connected on the site. “The number of distinct social contexts represented on Facebook … predicts the probability of joining.”
  • An invitation to join Facebook that listed four unrelated site users sent to a potential user was more than twice as likely to prompt the individual to join than an invitation that listed four connected users. “It is not the number of people who have invited you, nor the number of links among them, but instead the number of connected components they form that captures your probability of accepting the invitation.”
  • Once a user joins Facebook, the structural diversity of his or her network also impacts the level of engagement: more active Facebook users have friends on the site spanning numerous social circles. “Simply counting connected components leads to a muddled view of predicted engagement…. However, extending the notion of diversity according to any of the definitions above suffices to provide positive predictors of future long-term engagement.”

The researchers conclude that “these findings suggest an alternate perspective for recruitment to political causes, the promotion of health practices and marketing; to convince individuals to change their behavior, it may be less important that they receive many endorsements than that they receive the message from multiple directions.”

Tags: Facebook

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