Blattman, C, Green, D, Ortega, D, Tobón, S, 2018. Hotspots interventions at scale: the direct and spillover effects of policing and city services on crime in Bogotá, 3ie Grantee Final Report. New Delhi: International Initiative for Impact Evaluation (3ie).
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This study investigates whether intensive policing and municipal services improved security on targeted hotspots, and whether these place-based strategies displaced crimes to nearby streets.
In Bogotá, one of Latin America’s largest cities, 59 per cent of residents report feeling insecure. Newly elected Mayor, Enrique Penalosa, has made reducing crime and violence one of the central aims of his term, which runs from January 2016 to December 2019. However, there is little evidence on how the city government and police can reduce crime and build legitimacy cost-effectively. The results of the current study are expected to help the city redeploy police and resources.
The evaluation answers the following questions:
- What is the relative and combined effectiveness of intensified policing and municipal services on citizens’ perception of risk of crime and the actual incidence of crime?
- What are the positive and negative spillovers of these interventions onto the rest of the city?
The study included two place-based security interventions. In the first intervention, which lasted for eight months, police increased the daily dosage of patrolling time from 92 to 168 minutes in 756 targeted street segments. Patrols occurred mainly during the day, though in hotspots located near bars and nightclubs, patrols were evenly distributed between the day and night. Apart from spending more time in these streets, the police didn’t alter any of their usual behaviour or activities.
For the second intervention, in 201 street segments that showed signs of physical disorder, municipal maintenance crews were deployed to diagnose which services were needed, and deliver the appropriate services to these streets. The maintenance teams repaired streetlights and collected garbage every few weeks.
A sub-set of street segments received both intensive policing and intensified municipal services.
Theory of change
The first intervention, hotspot policing, increases police presence in hotspots through the reallocation of police presence from street segments with less crime to those with more. Potential criminals and the community will then become aware of the increased police presence in these streets. The increased time police patrols spend in these segments increases the likeliness of apprehension and punishment. Because potential criminals are more likely to get caught, the expected cost of engaging in criminal activities in these areas rises. For some individuals, these higher costs will now outweigh the benefits of committing the crime, so they will no longer commit the crime, leading to a decrease in crime.
The second intervention aims to reduce street disorder and create an environment of lawfulness. Potential criminals will become aware of the improved physical environment and believe that police presence and other enforcement efforts are stronger at these locations. Therefore, the subjective perception of apprehension and punishment will rise, increasing the cost of engaging in criminal activity and thus decreasing crime.
The study used a randomised controlled trial design where 1919 highest crime street segments were randomly assigned to one of the four groups: (1) intensive policing; (2) intensive municipal services; (3) intensive policing and municipal services and (4) control.
The evaluation also estimated whether the treatments had any direct and indirect (spillover) effects. This was done by segregating the street segments into groups based on proximity to the treated hotspots: within 250 meters, 250 – 500 meters and beyond 500 meters from the treated hotspots.
To measure the impact of these interventions, researchers used police administrative data on reported crimes, a survey of 24,000 citizens and the location of each police patrol in the city every 30 seconds. The citizens survey measured self-reported crimes, perceptions of security, and attitudes towards the police and the local government. To measure the effects on neighbouring blocks, researchers used administrative crime data from the entire city (over 138,000 street blocks). They also collected survey data both from the experimental crime hotspots and from a representative sample of 480 street segments in the non-experimental sample.
The authors found a decrease in the number of reported crimes of about 12.6 per cent in streets targeted with intensive policing, and 10.2 per cent in streets targeted with municipal services. These differences, however, were statistically insignificant. On its own, intensive policing and municipal services did not lead to increases in security in hotspots.
The study did find that intensification of both forms of state presence simultaneously had large and statistically significant impacts on security. The results suggest there was a decrease of about 45.6 per cent in the number of reported crimes in streets targeted with both intensive policing and municipal services simultaneously. The combined effects of both interventions were largest on the highest crime hotspots.
An assessment of the displacement effects of the interventions revealed that the total crime deterred in targeted hotspots was modest and the results suggest that crime may have slightly increased in each of the (more than) 77,000 streets located within 250 meters of treated hotspot segments. When these displacement effects were added together, the study could not rule out the possibility that all directly deterred crimes were displaced to other neighbouring streets.
Implications for policy and practice
The authors conclude that intensive policing and municipal services alone do not lead to large or statistically significant increases in security around crime hotspots. However, the intensification of both forms of state presence simultaneously led to large positive impacts in security. Policymakers must make these place-based security interventions more effective on directly treated streets, for example, through more intensive state presence or less predictable policing. There is also a need to reduce the chances of adverse spillovers through various mechanisms, such as increasing general police presence, targeting crime clusters rather than individual segments, or combining place-based interventions with ones that target high-risk people and behaviours.