The predictability of international terrorism: A time‐series analysis

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Abstract
The study examines the predictability of international terrorism in terms of the existence of trends, seasonality, and periodicity of terrorist events. The data base used was the RAND Corporation's Chronology of International Terrorism. It contains the attributes of every case of international terrorism from 1968 to 1986 (n = 5,589). The authors applied Box‐Jenkins models for a time‐series analysis of the occurrence of terrorist events as well as their victimization rates. The analysis revealed that occurrence of terrorist events is far from being random: There is a clear trend and an almost constant periodicity of one month that can be best described by a first‐order moving average model. The fit of this model was tested both by statistical diagnostics and the accuracy of predictions based on this model compared to actual occurrence. However, the series of victimization rates did not reveal any predictability aside from the overall trend of an increasing level of victimization. The findings of the study are discussed by two approaches: the contagiousness of terrorism and the concept of media‐oriented terrorism. These two concepts, separately or combined, may explain some of the patterns revealed in the occurrence of terrorist events. However, they both highlight the part played by the mass media, either as a target for publicity‐seeking terrorists or as an influential factor in the process of contagion.