Increasing police patrols over large geographic areas, such as neighbourhoods, districts or force areas, to reduce crime.
This summary is part of the Crime Reduction Toolkit, which presents the best available evidence on what works to reduce crime.
Focus of the intervention
This intervention focuses on increasing police patrols over large areas, such as neighbourhoods, districts and force areas, with the aim of reducing crime in those areas.
Patrols can be increased reactively (as a response to an increase in crime), proactively (to prevent a predicted increase in crime rate), randomly, or as a result of internal policing factors (such as an increase in police officers) or because of external factors (such as highly publicised events).
The strategy of increasing patrols over large areas contrasts with hot spots policing, which involves increasing patrols in small areas with persistently high levels of crime and disorder. Hot spots policing has been shown to be an effective way of using patrols to reduce crime.
This summary is based on one meta-analytic review covering 17 studies, which focuses on the effect of increasing patrols over large areas on:
- overall crime rates (17 studies)
- violent crime (13 studies)
- property crime (11 studies)
- drug/disorder offences (three studies)
The results of these studies were pooled in a meta-analysis, which yielded 90 tests of the intervention.
The review also investigated whether crime was displaced to neighbouring areas following the increase in police patrols (four studies yielding 34 effects).
Of these studies, 15 were from the USA, one from the UK and one from Uruguay.
Effect – how effective is it?
The evidence suggests that increasing patrols over large areas has, overall, reduced crime. The meta-analysis found that increasing police patrol over large areas led to an overall reduction in crime compared to areas where police patrol remained the same. Crime decreased by 9% in areas with increased police patrol.
The meta-analysis which used a general outcome measure reported both increases and decreases in crime within the individual studies it included.
The four studies that looked at crime displacement found no evidence that increasing police patrols over large areas had caused crime to move elsewhere.
How strong is the evidence?
The review was sufficiently systematic that most forms of bias that could influence the study conclusions can be ruled out.
The review considered many elements of validity, conducting relevant statistical analyses and using multiple coders to ensure the accuracy of information. It also considered the possibility of publication bias. However, the review included studies that used a wide range of research methods: unmatched control group designs, matched control group designs and Randomised Controlled Trials (RCTs), introducing variability which was not controlled for.
Mechanism – how does it work?
Increasing police patrol across large areas is assumed to reduce crime by increasing the visibility of the police. Increased visibility is thought to deter crime by increasing the perceived risk of apprehension among potential offenders, and decrease the opportunities that they have to commit crime. However, these assumptions were not empirically tested, as the original studies included in the meta-analysis did not provide the necessary information to do so.
Moderators – in which contexts does it work best?
There is evidence that the effects of increasing police patrols over large areas vary by context. The review analysed whether the amount of additional policing patrols, crime type and area size influenced the effects of police patrols.
Moderator analysis found that, as the police patrol time increased, so did the crime reduction effect. A 100% increase in patrols led to a statistically significant 14% decrease in crime.
The crime reduction effect of increased police patrols also varied by crime type:
- Property crime: an 18% relative decrease in crime (based on 11 studies). The difference was statistically significant.
- Violent offences: 11% relative decrease in crime (based on 13 studies). The difference was statistically significant.
- Drug and disorder offences: a 23% increase in crime (based on 3 three studies). The difference was not statistically significant.
The review also analysed the effects of area size on crime reduction. This analysis compared increases in police patrols at a beat level with those across larger areas, such as neighbourhoods, districts or divisions. Police patrols resulted in a statistically significant reduction in crime when increased across beats (a 12% reduction) but not when increased across larger areas (an 7% reduction). However, the difference in crime reduction between beats and the larger areas was not statistically significant, meaning it was not possible to conclude that area size made a difference to outcomes.
Implementation – what can be said about implementing this initiative?
The review found that the more police patrols were increased over large areas, the bigger the decrease in crime rates.
The review also made the following policy recommendations. These were not empirically tested, as the original studies did not provide the necessary information to do so:
- Police patrols should be increased in large areas with high crime, rather than in random areas. Officers should be provided in-depth information on the crime types present in their patrol area.
- Hot spots policing is likely to lead to higher reductions in crime than increasing patrol over large areas at random. The review speculated that a hybrid approach that increased patrols in hot spots over large areas, might be cost-effective.
Economic considerations – how much might it cost?
The review did not mention the costs or benefits of increasing police patrols over large areas, and no formal economic analysis was provided.
General considerations
- The majority of studies (15 out of 17) were conducted in the USA. Only one study was conducted in the UK, so the findings may not translate to a UK context.
- The review included studies that varied in their evaluation designs and outcome measures. Evaluation designs included unmatched and matched control designs and RCTs, and outcome measures included police recorded crime and public calls for service. These differences were not considered in the meta-analysis.
- Previous studies suggest that the initial crime-reducing effects of increasing the numbers of police patrol reduce over time. However, this was not tested in the current review.
Summary
The evidence suggested that an increase in police patrols over large areas reduced crime rates overall, with the most significant reductions being for property crimes and violent offences. The review found no significant decrease in drug and disorder offences. Increasing police patrol over large geographical areas also does not appear to displace crime to surrounding areas.
Larger increases in patrols were linked to larger decreases in crime. The review also suggested that any increase in police patrol across large areas should focus on higher crime areas, and could be combined with hot spot policing.
There was no difference between beats and larger areas in terms of the effect of increased patrols on crime.
Reviews
Review one
Reference
Weisburd D and others. 2024. ‘Can increasing preventive patrol in large geographic areas reduce crime? A systematic review and meta-analysis(opens an external website in the same tab)’, Criminology and Public Policy, 23(3), pp 721–743.
The review authors were contacted to provide further detail for clarification on the statistical analyses.