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10 March 2009

Twitter and the strength of weak ties

The following is in regards to:

Social networks that matter: Twitter under the microscope
by Bernardo A. Huberman, Daniel M. Romero, and Fang Wu
First Monday, Volume 14, Number 1 - 5 January 2009

The best thing about this study, for me at least, is that it encouraged me to finally read Mark S. Granovetter's The Strength of Weak Ties, and The Strength of Weak Ties: A Network Theory Revisited.

As for Twitter, the study is interesting both for its methodology and its findings, though the latter are not surprising:

• The number of posts (or tweets) increases as the number of people following a Twitter user increase, but only to a point, beyond which the level of tweets saturates.
• The number of posts increases as the number of friends increases, with no saturation point being reached. Friends in this case being defined as people who direct messages to each other (as opposed to messages that are broadcast to all the users followers).
• The number of friends is very small compared to the number of followers.
• The total number of friends reaches a saturation point, presumably due to the effort required to maintain a friendship, while the number of followees can continue to increase due to the lack of effort required to add one.
• Friendship tends to be reciprocated even though the study's definition of friend does not require reciprocity.

Where I take issue with the study is in the authors' declaration that "the social network that matters" is the smaller network of reciprocal friendship ties. Having invoked Granovetter in the second paragraph, no further use is made of his work, and that's unfortunate, because it sheds light on the issue of which ties matter, when, and why.

At the risk of over-simplification, weak ties, particularly what Granovetter calls bridging weak ties, are what bind more dense networks characterized by strong ties. Weak ties make a community out of small, otherwise disparate networks based on strong ties. The difference between the warp and the weft in woven fabric makes a good analogy. The warp is the stronger thread, held tight in the loom, while the weft can be made of weaker thread because it is not held under pressure. Nevertheless, it is the "weaker" weft that binds the warp threads together to make whole cloth.

Whether weak or strong ties matter is not characteristic of the network itself, but rather something that the researcher imposes on the network, based on the question(s) they seek to answer. For example:

• If I am studying adherence to a particular form of Islamic extremism, the weak ties are what interest me, because they represent the lines of communication along which the ideology spreads.

• If I am seeking to identify groups of adherents to that ideology, people who may be willing and able to engage in violent activities, the strong ties become more important, because a small, dense network of strong ties is more likely in my estimation to result in an effective terrorist cell.

And finally, something that is implicit in strength of weak ties theory: under stress, strong ties will become stronger, and weak ties weaker, resulting the breakup of the community of extremists. The weft fails and the fabric frays.

See also:

The Strength of Weak Ties, Mark S. Granovetter, The American Journal of Sociology, Vol. 78, No. 6 (May, 1973), pp. 1360-1380, The University of Chicago Press, http://www.jstor.org/stable/2776392.

The Strength of Weak Ties: A Network Theory Revisited, Mark S. Granovetter, Sociological Theory, Volume 1 (1983), pp 201-233.

Posted on 10 March 2009 @ 18:22

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