Understanding how terrorist groups operate is hard, not least because of a severe lack of information about how they recruit, organize, and plan their activities. So it’s no surprise, then, that working out how best to stop these organizations is tricky.

Now Aaron Clauset from the Santa Fe Institute, in New Mexico, and his pal Kristian Skrede Gleditsch say that they’ve found an important new insight into terrorist activity that could help solve this problem.

The analysis is based on the one set of reliable data that we do have: the number and severity of terrorist attacks and a rough idea of the size and age of the groups that carried them out (researchers looked at the data from 1998 to 2005). Clauset and Gleditsch say that a simple analysis of this data shows that the frequency of attacks increases over time in a pattern that is common to all groups: the time between attacks plotted against the group’s experience decreases according to a power law.

That can be explained in two ways. First, terrorist groups are born clumsy and increase their attack rate primarily because their members learn to be more efficient. In the manufacturing industry, this kind of organizational learning is called learning by doing and is widely studied.

Second, the terrorist groups are born small and increase their attack rate by recruiting new, replaceable members–a process called organization growth that is, again, well studied by economists.

Perhaps economics can help. “In this light, terrorist groups may best be understood as firms whose principal product is political violence, and whose production rates depend largely on organizational growth and the availability of low-skill labor,” say Clauset and Gleditsch.

That may well be an important insight because it implies that certain kinds of easily accessible organizations, such as nonprofit companies and groups of political activists, might be good models of terrorist groups from which additional insights can be gained. For example, it may be possible to determine whether the activity in a group is best reduced by limiting its growth or by disrupting its organization.

But there is a puzzle in this data, say Clauset and Gleditsch. The severity of terrorist attacks is independent of the size and experience of the organization. So contrary to what you might expect, young and old terrorist groups are equally likely to carry out extremely severe attacks. “Internal factors seem to play a marginal role in the severity of any particular attack,” say Clauset and Gleditsch.

Here’s one explanation. Similar kinds of power laws are common in the real world: in the size of stock-market crashes, the number of deaths in wars, and the severity of forest fires. In these cases, the size of the conflagration has nothing to do with the size of the event that triggered it, but everything to do with the network in which the event took place.

Perhaps the same is true with terrorist attacks: the severity of the attack has more to do with the properties of the system being attacked than with the organization doing the attacking.

Ref: arxiv.org/abs/0906.3287: The Developmental Dynamics of Terrorist Organizations