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  This module is a resource for lecturers  

 

Systematic reviews

 

Systematic reviews summarize and evaluate the best available research on specific programmes and interventions (Campbell Collaboration, 2018). The results from multiple high-quality studies are synthesized to produce the best possible evidence. The summaries below provide an indication of the types of crime and justice systematic reviews produced by the Campbell Collaboration. Further reviews are available on the Campbell Collaboration website.

 

The Effectiveness of Neighbourhood Watch

 
  • Authors: Trevor Bennett, David Farrington, Katy Holloway
  • Published Date: 31 December 2008
  • Background: The concept of Neighbourhood Watch emerged from a shift in societal perceptions about crime prevention. Since the 1980s, criminal justice institutions began to think differently about crime control and prevention (Garland, 2001). Crime was no longer the responsibility of only the State and its institutions, rather, ordinary citizens were seen to hold some level of responsibility to actively prevent the occurrence of crime and ensure their personal safety. Neighbourhood Watch schemes vary between areas but, in essence, they encourage citizens to be aware of activities that occur in their own neighbourhoods. If citizens come across suspicious activities, they should report this to the police. In theory, Neighbourhood Watch schemes should have the effect of reducing crime because the opportunities to commit crime have reduced and police detection is enhanced.
  • Objectives:
    • Assess the effectiveness of Neighbourhood Watch style schemes in reducing crime.
  • Selection/Exclusion Criteria:
    • Studies had to include a watch scheme, as opposed to some of the other elements that come with Neighbourhood Watch schemes, such as; property marking and security surveys.
    • The methodology had to include either RCTs or a pre- and post-test design with an appropriate comparison area.
  • Data Collection and Analysis: A search of eleven electronic databases found 19 eligible studies. The 19 studies covered 43 Neighbourhood Watch schemes, and they formed the basis of the narrative review. A meta-analysis was done on twelve of the eligible studies, which covered 18 Neighbourhood Watch schemes.
  • Results: The narrative review found that most of the Neighbourhood Watch schemes effectively reduced crime. The meta-analysis found that the weighted mean odds ratio for all studies was 1.19 using used the fixed effects model and 1.36 using the random effects model. The 1.19 result from the fixed effects model means that crime increased by 19% in the control areas compared to the treatment areas or decreased by 16% in the treatment areas compared to the control areas. The 1.36 result from the random effects model means that crime increased by 36% in the control areas compared to the treatment areas or decreased by 26% in the treatment areas compared to the control areas.
  • Conclusions: The authors concluded that Neighbourhood Watch schemes were positively associated with a reduction in crime.
  • Limitations: This study is prone to common limitations, i.e. included studies were conducted in Western countries only, there was a lack of high quality studies, and there were significant differences between the studies. Some of the original studies also compared the treatment area with a vastly non-equivalent control area. Other studies only used the raw number of reported crimes to measure effectiveness as opposed to using a reported crime rate per 100,000 population.

Furthermore, the studies used in the narrative review differed greatly to those that were included in the meta-analysis. Studies included in the meta-analysis were more likely to result in a positive correlation between Neighbourhood Watch schemes and reduced crime rates in comparison to the excluded studies. If all eligible studies were included in the meta-analysis, the end result would have been more modest.

 

Effects of closed circuit television surveillance on crime

 
  • Authors: Brandon Welsh, David Farrington
  • Published Date: 2 December 2008
  • Background: Closed circuit television (CCTV) surveillance cameras are used in numerous public and private spaces, often with the purpose of deterring criminal activity. However, the implementation and maintenance of extensive CCTV systems represent significant costs to the State, and ultimately the taxpayer. Thus, it is important to evaluate the effectiveness of CCTV cameras in the prevention of crime and whether the expense can be justified. Limited public resources imply that the crime prevention strategies implemented should be the ones that result in the greatest utility for the community.
  • Objectives:
    • Assess the available evidence on the effects of CCTV cameras on crime in public spaces.
    • In what settings are CCTV cameras most effective at preventing crime? E.g. city centres or car parks.
    • Which types of crimes are CCTV cameras most effective at preventing?
    • Under what conditions does CCTV cameras operate most effectively at preventing crime?
  • Selection/Exclusion Criteria:
    • Studies had to have an evaluation design that involved before and after measure of crime in both treatment and control areas.
    • Studies had to focus on CCTV intervention on crime, studies that included more than one type of intervention must have CCTV as the main intervention to be eligible.
    • Each area must have had a minimum of 20 incidences of crime prior to the CCTV intervention.
    • Studies must have included one treatment area and one reasonably comparable control area.
  • Data Collection and Analysis: 44 studies met the inclusion criteria for this review. 41 of the 44 studies were used in the meta-analysis. Three studies were excluded from the meta-analysis because they did not report crime numbers in their study and thus effect sizes could not be calculated. The 44 studies were categorized by the setting in which they were conducted, the majority fell into one of the following four categories; city and town centres, public transport, public housing and car parks. Two of the studies were conducted in residential areas and one was conducted in a hospital. In addition to the above objectives, displacement of crime and diffusion benefits of CCTV cameras were also evaluated.
  • Results: CCTV surveillance has a modest effect on personal property crime but not on levels of violent crime. CCTV surveillance is most effective in reducing crime in car parks and reducing vehicle related crimes within car parks. The evidence also indicates CCTV surveillance is more effective in the United Kingdom than other Western countries. The evidence did not indicate whether CCTV bears displacement or diffusion effects.
  • Conclusions: The authors concluded that CCTV cameras should continue to be used as a crime prevention strategy in public spaces, but using a targeted approach rather than the universal approach in place at the time of the study. They also confirmed the need for continual high-quality evaluations of CCTV schemes with long follow-up periods.
  • Limitations: Although the findings indicated CCTV was more effective in the United Kingdom, 36 of the 44 eligible studies were originally conducted in the United Kingdom. Five of the studies were conducted in the United States, and one study was conducted in each of the following countries: Canada, Norway and Sweden. 

Additionally, there were six studies of CCTV in car park settings and none of their interventions consisted solely of CCTV cameras. Other crime prevention measures, such as; better lighting, extra security guards and fencing were implemented along with the CCTV intervention. Thus, the positive effects of CCTV surveillance in car parks may be overstated. It is not possible to determine the extent of each component in its contribution to the overall reduction in crime.

 

Effects of improved street lighting on crime

 
  • Authors: Brandon Welsh, David Farrington
  • Published Date: 25 September 2008
  • Background: Street lighting in public spaces are a public good that serves a multitude of purposes. It aids both pedestrian and traffic safety, as well as serving a potential role in crime prevention. In theory, street lighting can prevent crime by increasing the surveillance or visibility of what occurs in public spaces. It decreases the opportunity for potential offenders to commit crimes because they can be easily seen by others. People are also more likely to use public spaces that are well lit, which furthermore increases the ability to survey the activity that occurs in the public space. Another theory explains that improved street lighting has the effect of reducing crime because it signals community investment in an area, which then leads to increased community pride, cohesiveness and informal social control.
  • Objectives:
    • Assess the available evidence on the effects of improved street lighting on crime in public spaces.
    • In what settings is improved street lighting most effective at preventing crime?
    • Which types of crimes are improved street lighting most effective at preventing?
    • Under what conditions does improved street lighting operate most effectively at preventing crime?
  • Selection/Exclusion Criteria:
    • Studies had to have an evaluation design that involved a before and after measure of crime in both treatment and control areas.
    • Studies had to focus on improved street lighting or lighting and, to be eligible, studies that included more than one type of intervention must have lighting as the main intervention.
    • Each area must have had a minimum of 20 incidences of crime prior to the implementation of improved street lighting.
    • Studies must have included one treatment area and one reasonably comparable control area.
  • Data Collection and Analysis: Database searches found 32 studies on improved street lighting. 19 of these did not meet the inclusion criteria and were thus excluded. 16 of those studies were excluded because they did not include a comparable control area. Ultimately, 13 studies were included for both narrative and meta-analysis.
  • Results:
    • Improved street lighting significantly reduces crime and, similarly to the review on CCTV surveillance, it is more effective in preventing crime in the United Kingdom compared to the United States. Furthermore, in areas with improved street lighting, night time crimes did not decline at a greater rate compared to daytime crimes.
    • The findings from the narrative analysis revealed that four of the eight studies conducted in the United States indicated street lighting was effective in reducing crime. Two of those studies showed that some displacement of crime had occurred and one study speculated that it was possible that displacement had occurred. In all five studies conducted in the United Kingdom, street lighting was effective in reducing crime.
    • The findings from the meta-analysis revealed that street lighting had a desirable effect on crime, with a weighted relative effect size of 1.27 - meaning that crimes increased by 27% in control areas in comparison to the treatment areas, or that crimes decreased by 21% in experimental areas in comparison to the control areas.
  • Conclusions: The authors concluded that improved street lighting should be continued to be used as a crime prevention measure in public spaces.
  • Limitations: Again, the findings from this systematic review are limited by similar factors outlined in the above reviews. This review only included studies conducted in the United States (eight) and United Kingdom (five). The generalizability of outcomes from developed Western nations need to be taken into consideration when utilizing this review to support the implementation of street lighting as a crime prevention measure in alternative contexts.

Furthermore, more research needs to be conducted to determine the mechanisms that enable street lighting to be either effective or ineffective in reducing crime. The fact that, in areas of improved street lighting, night time crime did not decline more than day time crimes indicates that community pride may be the explanatory mechanism at work, as opposed to increased visibility and surveillance.

 
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