The decades’ old overreliance on secondary sources of information is a long-standing problem in research on terrorism. Still, such data forms the basis on which the large majority of studies are built. Using secondary sources, such as newspaper articles or existing studies, poses several problems. Newspaper pieces or media sources more generally present problems of reliability and accuracy. Too frequently, such material contains factual errors or is to a greater or lesser extent distorted by the political preferences of journalist and editors or the simple wish to attract a readership through sensationalist reporting. Relying on academic publications should make these issues far less pronounced, yet raises the risk that the author is essentially recycling existing data and insights without adding anything of substance.

The ‘data problem’ is one of the reasons why terrorism expert Marc Sageman recently described research on the subject as being in a state of ‘stagnation’. Considering the large amount of funding that has poured into terrorism research since 9/11 and the fact that the number of books and articles on terrorism has skyrocketed since those fateful days in September 2001, Sageman’s critique is all the more deserving of our attention. Obviously this is an issue for which there is no quick or easy fix. There are, however, encouraging signs that the study of terrorism is moving away from its near-exclusive focus on secondary sources and literature-review based methodologies. One way of contributing to this ‘primary-sources turn’ in terrorism research is to critically re-examine well-known cases using newly available first-hand data.

A recently published article (anyone without access to the journal may request a complimentary copy by emailing the author) on the Dutch ‘Hofstadgroup’ takes precisely such an approach. By thoroughly revisiting what has been called a ‘quintessential’ example of homegrown jihadist terrorism using unique primary-sources based data, the authors make the case for a more nuanced reappraisal. On closer examination, the Hofstadgroup does not appear to have been as quintessential or even as clearly a ‘homegrown jihadist network’ as has been claimed. Beyond contributing to our understanding of this particular case, the findings underline the continuing deleterious effects of an overreliance on secondary sources on terrorism research.