Make that at least 7 Degrees of Separation

An interesting study by two Microsoft researchers (Eric Horvitz and Jure Leskovec) crunched the records of 30 billion electronic conversations among 180 million people from around the world, and found that any two people on average are separated by…..drumroll please….

6.6 degrees of separation. That means it would take 7 people or less to connect 78% of the pairs in their sample.

What the study doesn’t seem to address is that *6 degrees of separation* was meant to be a maximum (i.e., all people are connected by 6 or fewer links) not an average and the fact that the 180 million people using Microsoft’s IM Messenger are likely more connected than the most socially isolated individuals in the world. So on both fronts, I’d expect that the maximum chain length is longer than the 7 degrees of separation they found. Balancing this on the other side, it is very possible that if more individuals were included beyond the 180 million they included that one would find shorter social paths that went outside this group of 180 million individuals. The researchers note that just in their database, some of the 180 million individuals took as many as 29 links to connect.

The researchers considered individuals to be acquaintances if they had sent one another a text message.

The database they used was anonymized but covered all of the Microsoft Messenger instant-messaging network in June 2006, or roughly half the world’s instant-messaging traffic at that time.

See an earlier post on the 6 degrees of separation issue here (which includes some background on the “6 degrees of separation” idea and where it came from).

Researchers claimed that this research could aid political organizations, charity efforts, natural disaster relief and missing-person searches.”They could create large meshes of people who could be mobilized with the touch of a return key,” Horvitz said.

View the paper, “Planetary-Scale Views on a Large Instant-Messaging Network” here.

And see Bill Sherman‘s interesting comment below.


One response to “Make that at least 7 Degrees of Separation

  1. Thomas, this is an absolutely fascinating study, and I spent last night and this morning considering the implications.

    Three aspects really surprised me.

    1) MSN tops out at 600 “buddies” unlike human soical graphs that can contain many more first-level “weak ties.” I’m thinking that this artificial constraint would make it harder to have short connections.

    2) The study was focused on a communications graph:

    “We created an undirected communication network from the data where each user is represented by a node and an edge is placed between users if they exchanged at least one
    message during the month of observation.”

    So, if you used MSN during June 2006, you were, on-average, 6.6 contacts away from any other MSN user within the social graph. So, the Lekovec and Horvitz study seems to examine a communication network through the limited lens of recent contacts.

    Milgram’s “Small World” experiment allowed participants to leverage anyone within their network–not just people they’d contacted in the last month.

    We all have good friends (past colleagues, college friends, friends from other cities) who we stay in touch with but don’t contact monthly (let alone monthly through IM).

    Leskovec and Horvitz provide a snapshot of an active communication graph at a moment in time (the month of June 2006). But they seem to be measuring something different than what Milgram measured, but the findings are really very interesting.

    If Milgram had limited his participants simlilarly, I wonder what the results would have been. Imagine if Milgram’s letter said participants could only forward the letter to recent contacts (people they had interacted with in the last month).

    My instinctive guess would be that it would have taken many more jumps for the average letter to get between Omaha and Boston in the 1960’s. I also expect there would have been many more “broken chains” of letters that never reached the target recipient.

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