Hugh Pickens writes writes "Statisticians make predictions about all kinds of phenomena governed by power laws, everything from earthquakes, forest fires and avalanches to epidemics, the volume of email and even the spread of rumors. Now "This Week" reports that two statisticians — Aaron Clauset at the Santa Fe Institute in New Mexico and Ryan Woodward at the Swiss Federal Institute of Technology — have put together a comprehensive global database including 13,274 terrorist events from 1968 to 2007 and created an algorithm to predict the odds of a large-scale terrorist attack with similar or greater consequences happening again. They estimated that the historical probability of an attack on 9/11's scale happening at anytime in the last 40 years was somewhere between 11 and 35 percent. "That's important," says Technology Review. "It means that 9/11 itself was not at all unlikely given the pattern of terrorist activity leading up to it." Assuming that the number of terrorists events per year remains roughly what it is now (2000 per year), the likelihood of another large-scale terrorist attack anywhere in the world (with a death toll greater than or equivalent to 9/11) is between 20 and 50 percent over the next decade (PDF). A 50-50 chance, the top of that range, means "a catastrophic attack is as likely as not.""