Christakis and Fowler’s “Connected” explains the power of social networks

When I began thinking about social network analysis, the “Six Degrees of Kevin Bacon” game was the first mental association I made.  The object of that game is to pick an actor and trace their connection to Kevin Bacon through movie co-stars.  The folklore of the game is that every actor can be associated to Kevin Bacon by looking at chains of shared co-stars.

The shortest path between Emma Watson and Kevin Bacon is 2, since both starred with John Cleese
(c) Randy Olson

The game was created over 20 years ago, before websites like IMDB made it easy to track even the most obscure roles.  The advent of the internet has allowed people to create more detailed, intricate pictures of how actors are connected to Kevin Bacon, as well as to all other actors.  In an article for Business Insider, Randy Olson used IMDB to determine that actor Eric Roberts was connected to more actors than Kevin Bacon.  He found that 88% of all actors could be connected to Eric Roberts in three degrees or less, compared to 82% who could be connected to Kevin Bacon in the same amount.

Christakis and Fowler (2009) mentioned the Kevin Bacon game in their book Connected: How Your Friends’ Friends’ Friends’ Affect Everything You Feel, Think, and Do.  This book walks the reader through social network theory – the science of understanding the ways that people are connected.  Christakis and Fowler explained that relationships with people in our lives shape our attitudes, behaviors, and even health statuses. This assertion in and of itself was not groundbreaking. Christakis and Fowler went on to explain, however, that these parts of our lives are also impacted by people we may not even know – the friends of our friends’ friends.  The strongest influencers in our lives are those within three degrees of us in our social networks.

Happiness is contagious!!
Your kindergarten teacher was right – happiness is contagious.

The authors cited research and real world experiences to support social network theory.   They gave examples of how health issues, such as obesity and STDs, spread through social networks.  Even though STDs are communicable and obesity is not, the social network patterns were remarkably similar.  These patterns also showed up in happiness levels, voting behaviors, and how people found partners and jobs.

Technology has changed how we form networks.  It has increased the number of people with whom we can connect.  Christakis and Fowler found, however, that our offline and online networks tend to be similarly sized.  They point to evolution and genetics as factors that guide the size of our networks.  Sites such as Facebook increase the complexity of our social networks, but they do not replace our in-person networks.  The same rules apply in all social networks – we are all connected to each other, our behaviors and norms influence each other, and the most significant influences come from people within three degrees of separation.

Your friends’ friends’ friends


2 thoughts on “Christakis and Fowler’s “Connected” explains the power of social networks

    • September 10, 2017 at 8:41 pm

      Yes – I was struck by both the consistency and messiness of network patterns. The “real life” large group networks were much more complicated than what I ever imagined. I also about how slight changes can result in vastly different networks. Someone who serves as a broker role in between two networks has a tremendous amount of power – if their relationship disintegrates with the person they are linked to then the two networks separate. However, if the relationship grows stronger then the networks could become closer. The ability for networks move and grow and shrink is astounding.


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