Henry H. Willis and Brian Michael Jenkins
Vacationers considering trips to Belgium, France, London or other destinations in Europe may find themselves asking: Is it safe to travel there?
This anxiety is understandable, given deadly terrorist attacks in Brussels and Paris and, more recently, possible terrorist involvement in the crash of an EgyptAir plane out of Paris. In some cases the anxiety is reinforced by official travel warnings and security advisories reminding people to exercise vigilance. But an examination of the historical record of terrorism in the United States and Europe from 1970 to 2013 suggests that the threat of terrorism need not affect individuals' behavior and travel decisions — not even in the wake of significant attacks like those in Brussels and Paris.
Inherent in the concern expressed by travelers is the presumption that such attacks come in clusters, that a major terrorist attack somehow increases the likelihood that another one will soon occur. But is that really true?
Our analysis found that the distribution of small but fatal terrorism events (those killing at least one but less than three people) appears not to have been random in Europe and the United States between 1970 and 2002, but it does appear random between 2003 and 2013. In the earlier period, events were more inclined to occur in clusters, but not so for the most recent years.
We also found that larger events that kill three or more people, like those in Brussels and Paris, were not necessarily followed by additional attacks within the month that follows. From 1970 to 1993, trigger events did produce statistically significant clustering in their wake. But between 1994 and 2002, occurrences of small events did not significantly relate to trigger events. Again, in the most recent years, there was no statistical clustering of the kind that might indicate a surge in terrorist activity or the occurrence of deadly copycat attacks.
The article's full-text is available here.
