‘Focused deterrence’ holds promise for reducing serious violence

‘Focused deterrence’ holds promise for reducing serious violence. Here, Prof. Iain Brennan and Dr Tia Simanovic from the University of Hull discuss the Youth Endowment Fund and Home Office-funded ‘Another Chance’ project, one of the most ambitious and comprehensive evaluations of focused deterrence ever undertaken.

Reducing violence in communities has become a topic of extensive research in recent years. Various interventions have been developed, each addressing different aspects of the problem. Some interventions, like cognitive behavioural therapy, focus on changing people’s thinking patterns and providing non-violent solutions to life’s challenges. Others aim to address inequalities and missed opportunities by offering skills training and occupational support. Hot spots policing disrupts violence by creating obstacles to offending, while diversion programmes use critical moments in a person’s life, such as arrests or hospitalisation, to introduce opportunities for desistance. One particularly promising approach to reducing violence is called focused deterrence.

What is focused deterrence?

This multi-faceted intervention typically targets groups of males in urban centres, often in their late adolescence or early adulthood, who are involved in serious violence. It involves three main components: enforcement, support, and community influence. Participants are informed that their involvement in violence has drawn attention from law enforcement and other agencies, and they are offered support to help them make the decision to stop engaging in violence. Community leaders also express the unacceptability of violence through various channels, including face-to-face ‘call-in’ events. Focused deterrence interventions in different places vary in the emphasis they put on enforcement or support, or group vs individual responses, but they are usually carried out in collaboration with police, local statutory agencies, community/voluntary sector organisations and community members.

What is the evidence base?

While focused deterrence interventions have been implemented in many cities worldwide, particularly in the US, it is important to consider the limitations of the evidence base around their effectiveness. For example, some evaluations of these interventions lacked rigorous study designs, making it challenging to determine causal effects. Additionally, the extreme levels of violence in some cities where these interventions were implemented may have affected the outcomes through a process known as ‘regression to the mean’. In other words, very high levels of crime are likely to be temporary and to naturally move back towards the average, or the “mean”, when measured again. Also, differing contexts mean that US evidence and programmes do not always replicate well in the UK. For example, US evaluations have primarily focused on extreme outcomes, such as firearm incidents and homicides, which may not translate well to violence in other contexts like the UK, where knife crime is more prevalent than gun crime.

Efforts to implement focused deterrence in the UK have had limited success and encountered implementation challenges. Evaluations of previous interventions in Glasgow, London and Northampton produced inconclusive results or faced significant implementation challenges leaving several questions about how it could work in the UK.

YEF’s Another Chance focused deterrence programme

Recognising the potential of different intervention types and the need for stronger evidence, the Youth Endowment Fund (YEF) launched its Agency Collaboration Fund in 2021, co-funded by the Home Office, as part of its place-based grant rounds. This fund aims to build a stronger evidence base for multi-agency collaborations in violence prevention. It seeks to answer crucial questions about partnership models, local conditions and contexts, and effective agency collaboration activities. Focused deterrence is one of the interventions explored within this funding round.

To implement the focused deterrence programme, Violence Reduction Units and Police and Crime Commissioners were invited to apply for funding to run and evaluate the programme in a defined geographic area. Successful sites were asked to develop interventions aligned with six core principles of focused deterrence:

1. Identification
2. Eligibility
3. Contact and initial engagement
4. Services and Community Support
5. Enforcement
6. Exiting the programme

This approach allowed for flexibility within a framework, ensuring that the programmes were acceptable to local communities and stakeholders. It also provided insights into how focused deterrence interventions could be developed and implemented in England and Wales.

After extensive collaboration and discussions between the delivery teams, evaluators and the YEF, a multi-site, randomised controlled trial was developed across five cities in England: Manchester, Leicester, Nottingham, Coventry, and Wolverhampton.

Evaluating the Programme: Challenges and Solutions

The YEF’s and the Home Office’s goal is to prevent young people from getting involved in violence, relying on rigorous evidence to determine what interventions are effective. One commonly used method to assess the impact of an intervention is a randomised controlled trial (RCT), where participants are randomly assigned to either receive the intervention or not, and their outcomes are compared. While this approach is seen as the gold standard for evidence that something is effective, implementing RCTs can be challenging.

1) Group vs individual effects

Evaluating focused deterrence interventions using groups as the treatment unit poses specific challenges. The nature of group violence and the potential for “contamination” between groups make it difficult to determine if an intervention with one group caused a change in violence. Additionally, the sample sizes required to make a randomised controlled trial work have rarely been met in the focused deterrence literature and this would be even harder with groups. This creates a dilemma: evaluations of focused deterrence want to be group-based, rigorous and affordable, but it is challenging to achieve all three simultaneously.

To address these challenges and evaluate focused deterrence on a large scale, we have made a trade-off. Instead of using groups as the treatment unit, we are using individuals. Although focused deterrence has traditionally been delivered to groups, its components can be applied to individuals, and they operate at the individual level even when delivered to groups. While this approach allows for rigorous evaluation, the anticipated effect sizes are small, and the number of individuals available for individual trials is insufficient to achieve statistical power. To overcome this, we are pooling data from multiple sites.

2) Flexibility vs uniformity

Multisite trials assume uniformity (or homogeneity) in programme content, intervention population and evaluation design. However, the need for flexibility to account for local contexts presents a challenge. The interventions and their implementation vary across sites, including the context of violence, partnerships, community buy-in and resources. We will document these differences as part of the formative evaluation and examine the assumption of homogeneity. If the sites cannot be grouped into a single trial due to major differences in how they work, we will use meta-analysis techniques (where we combine the results of multiple studies), although they may suffer from limited statistical power.

3) Spillover

Another challenge we face is known technically as ‘stable unit treatment value assumption (SUTVA)’. In simple terms, it is the assumption that the individuals getting the intervention don’t affect the individuals not getting the intervention, and vice versa; or, that the effects don’t ‘spill over’ from one group to the other.

In this case, since violence involves interactions between individuals, preventing one person from being violent may deprive another person of a target. This inherent threat to SUTVA is an unavoidable cost of randomising violence prevention interventions at the individual level. We will, however, explore potential spillover effects between the intervention and control groups through interviews with participants and the delivery team. Understanding the role of peers and the plausibility of enforcement targeted at individuals will provide valuable insights.

An ambitious design

Adopting a ‘realist’ approach to our evaluation, we go beyond average treatment effects. This means that we aim to understand how the intervention works, for whom and in what context. This involves extensive observation of engagement and enforcement activities, interviews with stakeholders and the delivery team, and most importantly, with the programme participants themselves. Their experiences and impressions will provide crucial insights into the intervention’s effectiveness and potential unintended consequences. To support this effort, we have established local evaluation reference groups in each city, allowing us to tap into their knowledge and expertise on day to day lives in their cities so that we can interpret the results of the study correctly.

This evaluation is the most ambitious and comprehensive evaluation of a focused deterrence framework ever undertaken and represents an exciting opportunity to further our understanding of violence prevention and develop effective strategies. By exploring different intervention models and considering local conditions, we can make meaningful progress in reducing violence and creating safer communities.

You can read more about the project, evaluation design and timeline here.