Terrorist Attacks in Spain

On Thursday, March 11 2004, during the morning traffic of people going to work in Madrid, several bombs were exploded in commuter trains as they pulled into stations. These terrorist attacks were highly coordinated, with the first at 07:39, local time, followed closely by three more nearby. A few minutes later at 07:45 and 07:55, two more. About 200 people were killed and some 1500 were injured. At 10:10 two more bombs were found by police and detonated by bomb squads. Examination of the un-detonated bombs revealed that they were designed to explode when a mobile phone in the package was called.

I was traveling in Brazil, but the local papers had detailed reports on the attacks. I was able to establish the parameters of the formal prediction for later analysis. Two other people, Per Lassen and Dick Bierman, also suggested the Madrid bombings and the anti-terrorist demonstrations the next day (12 March) should be examined; they are included as predictors in the results table.

Following precedents from other terrorist attacks, I set the period from 07:00 to 12:00 as the formal prediction (6 to 11 GMT), to include some time before the first explosion and several hours of the aftermath. The trend over this period is extreme -- but it is a negative slope, opposite to the standard prediction. The Chisquare is 17634 on 18000 df, with corresponding p-value of 0.974. The first of the two following figures shows the formal analysis.

An exploratory examination of the context is shown in the second figure, which plots the data for the whole GMT day. It is apparent that the random walk changed at about the time of the terrorist attacks, and continued in an extremely unlikely negative trend for about 10 hours. While it is not appropriate to calculate probabilities for this selected segment, it is in the extreme tail of the distribution of such analyses performed for all days in the 5.5 year database. The long-continuing trend is reminiscent of the two-day persistence of deviation following the Sept 11 2001 terrorist attacks in the US.

Terrorist Attacks in Spain

Attacks in Spain

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