Monday, November 20, 2006

Network Theory Meets Complex Social Systems

Complexity in the Field
By J.B. Ruhl

Some innovative research on social networks reported in last week's Science reveals some challenges for network theory's explanation of complex social collective behavior. The NewsFocus article, Tracking People's Electronic Footprints, described the results of several experiments using tracking data from massive collections of cell phone, employment, banking, and other records. Some standard tenets of network theory came under question, as social collective behavior exhibited the unpredictability of complex adaptive systems:
  • Studies based on cell phone data from 7 million users in an undisclosed European nation revealed that stronly "intimate" relationships (measured based on frequency and duration of calls) tend to move information within tightly knit communities, where, contrary to classic network theory, it dead ends unless less intimate information relationships link the information over to other communities within the larger system. Using models based on the actual data, the research found that removing the most intimate connections in the overall system tends to break down some individual community relationships, but has little effect elsewhere in the system. By contrast, removing the same fraction of the weakest connections in the system causes the entire communication network to "shatter into islands." The researchers believe this is the first empirical, large-scale study confirming Stanford Professor Mark Granovetter's 1973 theory (see The Strength of Weak Ties) that "for keeping society connected, acquaintances are more important than close friends."
  • The other study examined the New York City garment industry, long a shining example of a massive social business newtork exhibiting impressive efficiency with no "master planner" and with actors unaware of the system's operations beyond their respective local parts. The problem is that in the face of foreign competition the industry has shrunk from 300,000 workers in 3000 firms to 190 firms today. By examining data from over 700,000 business transactions since 1985, the researchers were able to conduct the first large-scale study of a massive social network in contraction. When modeled using conventional network theory, the industry should have fallen apart, but instead it has stayed as robust as before, just smaller. Using a model based on the actual network behavior, the team believes they can demonstrate that "robustness is an unintended consequence of individuals following their own self-interest based on local information." Hmmm...that sounds familiar. Did Adam Smith use a cell phone too?


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