This CREST report provides an evaluative overview of risk assessment tools and methods used internationally to counter extremism

This report is primarily based on academic literature from 2017 onwards. To help address the limitations of this research it draws on some literature from outside this period, grey literature, and work from comparable fields, including risk assessments of violent offenders and sex offenders. The research included is international in scope, with an emphasis on work undertaken in the United States, the Netherlands and the UK.

The evidence base underpinning extremist risk assessments is not yet established. While risk factors associated with criminality have been extensively researched, those relating to extremism require a stronger empirical foundation. There has been little evaluation of the accuracy of risk assessment instruments specific to extremism, nor are there recognised standards for comparing their effectiveness. Further research is also needed to understand how these frameworks and tools are used in practice.

Key findings  

Although there is broad consensus on the risk factors associated with violent extremism, in most cases they have not been properly evaluated. Few studies compare the prevalence of risk factors in the general population with extremists or potential terrorists. This makes it difficult to know how reliable the risk factors identified in the literature are. 

Structured Professional Judgment (SPJ) has become the principal method for carrying out extremist risk assessments. SPJ provides assessors with empirically-based frameworks and tools to help support and organise their knowledge and inform risk assessment processes, including identifying opportunities for interventions or managing risk. SPJ involves some flexibility and supports, rather than supersedes, professional judgement.  

Risk assessment tools or instruments should not be considered complete solutions to the difficulties associated with interpreting risk. However, they can help identify and structure relevant information and make assessments as informed and consistent as possible.

Even with specialist tools, the knowledge, experience, and expertise of assessors remain critical. Whilst some SPJ frameworks contain ‘relevance ratings’ that highlight particularly significant factors, assessors must have the skills to weigh risk factors and put them in context as well as the confidence to apply discretion when using risk assessment instruments.  

Effective staff training is vital. Those conducting risk assessments need to be trained and supported to ensure tools are used accurately and consistently.

The predictive ability of risk assessment methods has not yet been fully evaluated. The comparatively low number of terrorism offences makes predictive risk assessment difficult. 

Measuring changes in dynamic risk factors, or those that vary over time or in response to treatment, is a complex process. Doing so requires multiple assessments that can be compared over time. Research from non-terrorism related offending highlights that risk assessments should be carried out frequently to strengthen their capacity to accurately predict future risks, something known as predictive validity. 

Further research is needed to understand how risk assessment tools are used in practice and how they can best be integrated and combined in the evaluation and decision-making process. Guidance about how to integrate different tools would help support practitioners and avoid inconsistencies in how assessments are carried out. 

Read more
  • Clemmow, C., Schumann, S., Salman, N, and Gill, P. (2020). The Base Rate Study: Developing Base Rates for Risk Factors and Indicators for Engagement in Violent Extremism. Journal of Forensic Sciences, 65:3, 865-881.
  • Geurts, R., Anders Granhag, P., Ask, K. and Vrij, A. (2017). Assessing threats of violence: Professional skill or common sense? Journal of Investigative Psychology and Offender Profiling, 14:3, 246–259.
  • Lloyd, M. (2019). Extremism Risk Assessments: A Directory. Centre for Research and Evidence on Security Threats report.
  • Logan, C. (2017). Reporting Structured Professional Judgement, in S. Brown, E. Bowen and D. Prescott (eds.), The Forensic Psychologist’s Report Writing Guide, London: Routledge, 82–93.
  • Van der Heide, L., Van der Zwan, M. and Van Leyenhorst, M. (2017). The Practitioner’s Guide to the Galaxy – A Comparison of Risk Assessment Tools for Violent Extremism. International Centre for Counter-Terrorism report.
  • Vergani, M., Iqbal, M., Ilbahar, E. and Barton, G. (2018). The Three Ps of Radicalization: Push, Pull and Personal. A Systematic Scoping Review of the Scientific Evidence about Radicalization into Violent Extremism, Studies in Conflict & Terrorism, DOI: 10.1080/1057610X.2018.1505686