Insurgent attacks follow a universal pattern of timing and casualties.
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"We found that the way in which humans do insurgent wars — that is, the number of casualties and the timing of events — is universal," says team leader Neil Johnson, a physicist at the University of Miami in Florida. "This changes the way we think insurgency works."
Johnson and his colleagues argue that the pattern arises because insurgent wars lack a coherent command network and operate more as a "soup of groups", in which cells form and disband when they sense danger, then reform in different sizes and composition. The timing of attacks, the authors say, is driven by competition between insurgent groups for media attention.
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The researchers collected data on the timing of attacks and number of casualties from more than 54,000 events across nine insurgent wars, including those fought in Iraq between 2003 and 2008 and in Sierra Leone between 1994 and 2003. By plotting the distribution of the frequency and size of events, the team found that insurgent wars follow an approximate power law, in which the frequency of attacks decreases with increasing attack size to the power of 2.5. That means that for any insurgent war, an attack with 10 casualties is 316 times more likely to occur than one with 100 casualties (316 is 10 to the power of 2.5).
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http://www.nature.com/news/2009/091216/full/462836a.htmlNote: this is a meta article; the real paper requires subscription to Nature (edit: or payment for article).