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Statisticians Calculate Probability of Another 9/11 Attack

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Twin Towers

Researchers estimate there is a 50% chance of another devastating terrorist attack, like the 9/11 attacks that destroyed the Twin Towers, within the next decade.


There is a 50 percent chance of another devastating terrorist attack within the next decade, according to statistics compiled by the Santa Fe Institute's Aaron Clauset and the Swiss Federal Institute of Technology's Ryan Woodward.

The researchers employed a dataset of more than 13,000 terrorist incidents between 1969 and 2007 to estimate the probability of an attack with a death toll equal to or higher than 9/11. Clauset and Woodward generated three calculations based on various possible distributions, and the 50 percent estimation of a likely catastrophic attack within the next 10 years assumes that the number of annual terrorist events remains the same as it is now—about 2,000 per year—if the power law distribution model is followed. The same model calculates 95 percent certainty that such an attack would result in more deaths than 9/11. It also can be argued that stabilization in Iraq and Afghanistan reduces the likelihood of a 9/11-scale attack in the next decade to between 5 percent and 10 percent.

Clauset and Woodward also estimated that the odds of at least one 9/11 event happening at any time in the last 40 years are between 11 percent and 35 percent, which means that 9/11 itself was quite probable in view of the pattern of terrorist activity that led up to it.

From Technology Review
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Abstracts Copyright © 2012 Information Inc., Bethesda, Maryland, USA 


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