Latest GRIEVANCE Publications

Modelling the spatial decision making of terrorists: The discrete choice approach

Zoe Marchment and Paul Gill


 Collectively, rational choice perspectives, routine activity theory and crime pattern theory suggest offenders actively select areas and targets in a way that minimises effort and risks and maximises rewards. Research suggests that a multistage hierarchical process in decision making occurs, whereby offenders select an area that is deemed suitable for the offence, before selecting the specific target. It is assumed the offender chooses the alternative that offers the best perceived utility, based on expected rewards, risks and effort.


 The discrete choice approach models target selection by considering multiple factors at the same time, and enables an impedance measure of distance to be treated as an explanatory variable. As well as the location that was selected for an attack, the model also allows for areas that were not chosen to be examined simultaneously, as well as also considering the origin of offender, and other defined factors that may affect decision making. This study used the discrete choice approach to analyse 150 attacks by 127 members of the Provisional Irish Republican Army (PIRA), living in the city of Belfast, Northern Ireland, in the period 1969–1989.


The findings provide further support that terrorists behave similarly to ‘traditional’ criminals in terms of spatial decision making when selecting targets. The results demonstrate the characteristics of target areas as well as the properties of their likely journey to the target influenced the location of PIRA attacks.

The model indicated that three of the variables affected the likelihood of an area being chosen as a target.

-       An increase in distance from the home location decreased the likelihood that the SA would be chosen.

- The presence of a major road increased the likelihood that an area would be selected.

-The presence of a military base or police station increased the likelihood that an area would be selected.

 The results provide support that decisions made by terrorists are guided by rationality, are similar to those made by traditional criminals, and are affected by associated risks and rewards.

 Full citation: Marchment, Z., & Gill, P. (2019). Modelling the spatial decision making of terrorists: The discrete choice approach. Applied Geography, 104, 21-31.Chicago        

Domestic extremist criminal damage events: behaving like criminals or terrorists?

Arlene Robinson, Zoe Marchment and Paul Gill


Localised activities of domestic extremism (DE) typically consist of activities, such as the destruction of property, that would constitute ‘criminal damage’ offences. These activities fall under a broad DE strategy of ‘direct action’, designed to cause operational difficulties, damage to reputation, and/or financial losses for the target. Property damage is a ubiquitous criminal direct action tactic perpetrated by left-wing extremists in Bristol to advance a variety of causes.

Like other extremist events, direct action acts committed by UK DEs are used to convey a message. As such, the offenders may have a limited choice set of targets that will be relevant to their ideology to choose from. The lack of an ideological basis guiding non-DE criminal damage events means that they may be taking different factors into consideration when selecting targets. For DEs, the selected targets are more likely to be of a symbolic nature, relevant to their ideology. Therefore, committing acts in more ‘public’ places may be necessary, and carried out regardless of SCP measures.


Using police data and online claims of responsibility, this study quantitatively analysed the target locations of 95 ‘direct action’ property damage incidents by left-wing extremists in Bristol. We compared these crimes with 95 conventional property damage incidents in the same area, to identify ways in which they differ. The variables related to situational factors providing guardianship at a target location, and were as follows: the presence of (a) capable guardians, (b) fencing, (c) lighting and (d) CCTV; the degree of target visibility; the target type (public/private building); whether the crime involved the use of an instrument.


The results suggest that left-wing extremists do not behave in the same manner as conventional criminals as they fail to conform to theoretical expectations regarding the effect of guardianship on target selection decisions. Instead, DEs appear to adhere to decision-making schemas more commonly associated with terrorists.

The perceived presence of a capable guardian did not have a significant effect on DE target selection compared to the non-DE sample. However, the presence of lighting and CCTV at a target location were significantly associated with DE events. DE events were more likely to occur in places where fencing was present when compared with non-DE criminal damage events, and were significantly more likely to occur in public places.

The different locations in which criminal damage offences plays could be indicative of a different behavioural underpinning. The lack of an ideological basis guiding non-DE criminal damage events means that they may be taking different factors into consideration when selecting targets. For DEs, where the selected targets are more likely to be of a symbolic nature, they may believe the potential rewards are worth the associated risks.

Full Citation:

Robinson, A., Marchment, Z., & Gill, P. (2018). Domestic extremist criminal damage events: behaving like criminals or terrorists?. Security Journal, 1-15.

Lone Actor Terrorists: A Residence-to-Crime Approach

Zoe Marchment, Noémie Bouhana and Paul Gill


As an individual navigates their city or town, travelling to and from their daily activity nodes (such as place of work or education, places of socializing or recreation) they will become more familiar with some areas than others. This increased familiarity increases the likelihood that these individuals will offend within that space, as they are more aware of criminal opportunities, as well as associated risks (such as chances of detection and interdiction). An offender’s journey-to-crime will typically demonstrate the distance decay effect, whereby the chances of offending and frequency of offences will decrease as the distance from the individual’s home increases. Where an individual has several equally attractive alternatives, they generally prefer the one that is closest to them.


Using a unique dataset of 122 attacks committed by 70 lone actor terrorists, we investigated the spatial decision making of lone actor terrorists in Europe and the United States. Journey-to-attack distances were computed for each attack using the home and target locations using Euclidean straight-line distance (the shortest distance between two points). Target choices were coded as either iconic, symbolic, or arbitrary.


The distance decay function that is evident for traditional crimes was replicated for lone actors - with the results demonstrating that frequency of attacks decreases as distance from home locations increases. Collectively, the statistical analyses and illustrative examples suggested that distance can be put forward as a constraining factor that governs the selection of targets. We conclude that lone actor target selection is a result of a confluence of distance and appropriate targets, whereby a target will be chosen where it is a) in the individual’s awareness space, b) within close proximity to the individual’s home location, and c) relevant to the individual’s ideology.

·      Lone actors tend to travel short distances to commit their attacks. 70% of attacks in Europe occurred within 5 miles of the offender’s home.

·      Individuals with links to a wider network travelled much further than those without. Those who had face-to-face interactions were over four times more likely to travel further than 10 miles.

·      The constraining effects of distance are different for the U.S. and Europe. The results for both continents demonstrate the distance decay pattern, but to a different degree, with individuals in the U.S. travelling further than those in Europe.

·      Individuals travelled further for iconic targets than symbolic or arbitrary targets, and further for symbolic targets than arbitrary targets. They also travelled much further for attacks where a symbolic building was present when compared with symbolic people. This suggests that a consideration of costs vs. benefits may take place in decision making regarding target selection, and that there is a trade-off between distance to the target and the representative value of the target.

·      Islamist and right-wing lone actors may behave in a similar way to “traditional” criminals in terms of spatial decision making when selecting targets. However, single-issue actors do not seem to be constrained by distance in the same way, possibly as many of this subgroup have a limited choice set of targets to choose from. For example, anti-abortionists in the U.S. may be forced to travel to different states due to the varying legality of abortions in different states.

Case Study:

Benjamin Nathaniel Smith was a right-wing extremist who killed 2 individuals and injured 10 in targeted attacks on ethnic minorities over a 3-day period in 1999. Smith began his attacks in the neighbourhoods surrounding his childhood home in Wilmette, where he had recently returned to live. These neighbourhoods were predominantly populated by Orthodox Jews as well as large numbers of immigrants. The following day, attacks took place at the first university he attended as well as two of the closest towns to the university by direct route. Finally, on the Sunday, he waited outside a Korean Methodist church near the second university he attended, before killing a graduate student as the congregation emerged. Smith had just finished his third year of college at this university, and was living in student accommodation less than half a mile away from this campus until a few months before his attacks.

This case highlights the importance of considering all locations in the individual’s awareness space, including previous addresses, places of work and education, as well as the areas surrounding their home.

Full citation:

Marchment, Z., Bouhana, N., & Gill, P. (2018). Lone Actor Terrorists: A Residence-to-Crime Approach. Terrorism and Political Violence, 1-26.