American Terrorism and Extremist Crime Data Sources and Selectivity Bias: An Investigation Focusing on Homicide Events Committed by Far-Right Extremists

Abstract

This paper examines the reliability of the methods used to capture homicide events committed by far-right extremists in a number of open source terrorism data sources. Although the number of research studies that use open source data to examine terrorism has grown dramatically in the last 10 years, there has yet to be a study that examines issues related to selectivity bias. After reviewing limitations of existing terrorism studies and the major sources of data on terrorism and violent extremist criminal activity, we compare the estimates of these homicide events from 10 sources used to create the United States Extremist Crime Database (ECDB). We document incidents that sources either incorrectly exclude or include based upon their inclusion criteria. We use a “catchment-re-catchment” analysis and find that the inclusion of additional sources result in decreasing numbers of target events not identified in previous sources and a steadily increasing number of events that were identified in any of the previous data sources. This finding indicates that collectively the sources are approaching capturing the universe of eligible events. Next, we assess the effects of procedural differences on these estimates. We find considerable variation in the number of events captured by sources. Sources include some events that are contrary to their inclusion criteria and exclude others that meet their criteria. Importantly, though, the attributes of victim, suspect, and incident characteristics are generally similar across data source. This finding supports the notion that scholars using open-source data are using data that is representative of the larger universe they are interested in. The implications for terrorism and open source research are discussed.

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Notes

  1. 1.

    The ECDB has received funding to expand its focus to include far-left and Al Qaeda inspired violent criminal activities and financial crimes by far-rightists and Al Qaeda inspired offenders. Since the focus of the analysis is on the far-right homicides, these data will not be discussed.

  2. 2.

    This study operationalizes the far-right as individuals or groups that subscribe to aspects of the following ideals: They are fiercely nationalistic (as opposed to universal and international in orientation), anti-global, suspicious of centralized federal authority, reverent of individual liberty (especially their right to own guns, be free of taxes), believe in conspiracy theories that involve a grave threat to national sovereignty and/or personal liberty and a belief that one’s personal and/or national “way of life” is under attack and is either already lost or that the threat is imminent (sometimes such beliefs are amorphous and vague, but for some the threat is from a specific ethnic, racial, or religious group), and a belief in the need to be prepared for an attack either by participating in or supporting the need for paramilitary preparations and training or survivalism. Importantly, the mainstream conservative movement and the mainstream Christian right are not included.

  3. 3.

    We attempted to review an 11th source, the Bureau of Justice Assistance (BJA) and Department of Defense (DOD) funded Institute for the Study of Violent Groups (ISVG) that tracks crimes committed by political extremists since 2002. Our requests for a listing of far-right homicides committed in the U.S. went unanswered.

  4. 4.

    We excluded the National Counterterrorism Center’s Worldwide Incidents Tracking System (WITS) database that includes terrorist acts committed since 2005 in our analysis because it only contained one far-right related homicide event. This homicide was included in the other sources we examined.

  5. 5.

    Six of the sources we used only included acts committed to further a “political” or “ideological” objective. These sources assume that ideologically motivated crimes are committed for a higher purpose and are different than routine crimes committed to further personal interests. The ADL, SPLC, the media and our coders focused however, on crimes committed by extremist suspects as opposed to events. Thus, these sources are interested in all homicides committed by far-rightists (both ideological and non-ideological). Our study assumes that the ECDB categorization of a homicide event as either ideologically motivated or non-ideologically motivated is accurate. In this sense, we are privileging the ECDB. For example, if the ECDB categorizes homicide X as ideologically motivated, while the FBI or GTD categorize it as non-ideological we code that event as ideologically motivated. While we appreciate critiques that question why the ECDB is treated as the ground truth, we make this determination for a few reasons. Again, the ECDB’s ongoing data collection efforts focus almost exclusively on homicides committed by far-rightists and other extremists in the United States. Further, the ECDB systematically searched through a series of open sources to identify these events twice. Conversely, most other data collection efforts focus on a much larger geographic universe and have a much larger N.

  6. 6.

    The FBI and databases like the GTD argue that while hate/bias-motivated crimes are related to terrorism, they are a separate phenomenon. Hate crimes are counted separately (e.g., the FBI’s UCR hate crimes report is distinct from the government’s annual terrorism reports). Non-hate crime ideologically motivated acts are thought to implicate broader political objectives that qualify as terrorist, while hate crimes do not qualify. Other sources disagree and sometimes conclude that ideologically motivated acts- anti- government or anti-minority- qualify and should be labeled terrorist. Here too we assume that the ECDB categorization of a homicide event as either a bias-motivated crime or not is accurate.

  7. 7.

    The FBI and sources that rely upon its definition (e.g., the ATS and Hewitt) conclude that acts committed by lone wolves usually do not qualify as terrorists. Groups like the IRA or Al Qaeda, 1998- 2001, are organized entities that engage in ongoing criminal activities designed to harm American interests. Conversely, lone actors usually lack the logistical support and infrastructure to conduct repeated attacks and to remain a longstanding threat to government interests. Thus, lone wolves do not implicate the same threat level and do not qualify as terrorist. Other sources conclude that ideologically motivated acts, regardless of the organizational level of the suspects who commit it, should be labeled terrorist.

  8. 8.

    The F.B.I. is charged with investigating domestic terrorism incidents and these incidents are subsequently prosecuted on the federal-level. Some sources again conclude that the jurisdiction of the prosecution is irrelevant and that what matters is whether the act is ideologically motivated.

  9. 9.

    The FBI defines terrorism as “the unlawful use of force or violence against persons or property to intimidate or coerce a government, the civilian population, or any segment thereof, in furtherance of political or social objectives” (FBI, 1997).

  10. 10.

    While Hewitt claimed to rely on the F.B.I.s definition, his precise methodology and validation scheme are unclear. He devotes only four pages, in an appendix, to his data sources and coding procedures. Further, as our analyses demonstrate Hewitt’s chronology includes lone actor, state-level and other attacks that should have been excluded under a strict application of the FBI’s guidelines.

  11. 11.

    There was the possibility that a homicide that occurred outside the time frame would be included in a source. SLATT reports legal decisions as these homicides progress through the criminal justice system. For example, it reported on the numerous appeals and court decisions related to the Oklahoma City bombing. We treated these cases as being included in the source even though they fell outside the time frame. In addition, Hewitt’s data collection ended 6/30/2004. Thus, we compare this source to the only the 1990–2004 homicides. Finally, the GTD does not include any incidents from 1993 thus we only compared this source for 1990–1992 and 1994–2008.

  12. 12.

    It is likely that a specific source relied on several of the other sources examined here to identify incidents. That is, these sources rely on other open sources, and thus the number of sources might be indicative of a single source that captured an incident, that was then used by the other sources.

  13. 13.

    We have excluded the FBI and ATS sources from these analyses because they focus only on federal cases.

  14. 14.

    All of the suspects for these incidents were male and white.

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Acknowledgments

The authors would like to thank the editors, and participants in the research seminar on methodological issues in terrorism that was convened at John Jay College of Criminal Justice in October, 2010 for helpful insights. The authors would also like to thank the reviewers and Erin Miller for their thoughtful suggestions for revision. In addition, we would like to thank Nick Corsaro and Jeremy Wilson for helping us think through the data analysis plan.

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Correspondence to Steven M. Chermak.

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This research was supported by the United States Department of Homeland Security Science and Technology Directorate’s University Program’s Division as well as its Human Factors and Behavioral Science Division both directly and through the National Consortium for the Study of Terrorism and Responses to Terrorism (START) through both research and education grants. However, any opinions, findings, and conclusions or recommendations in this document are those of the authors and do not necessarily reflect views of the U.S. Department of Homeland Security or START.

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Chermak, S.M., Freilich, J.D., Parkin, W.S. et al. American Terrorism and Extremist Crime Data Sources and Selectivity Bias: An Investigation Focusing on Homicide Events Committed by Far-Right Extremists. J Quant Criminol 28, 191–218 (2012). https://doi.org/10.1007/s10940-011-9156-4

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Keywords

  • Terrorism
  • Far-right violence
  • Selectivity bias