Reducing Violence by Transforming Neighborhoods: A Natural Experiment in Medellin, Colombia

Abstract

Neighborhood-level interventions provide an opportunity to better understand the impact that neighborhoods have on health. In 2004, municipal authorities in Medellín, Colombia, built a public transit system to connect isolated low-income neighborhoods to the city's urban center. Transit-oriented development was accompanied by municipal investment in neighborhood infrastructure. In this study, the authors examined the effects of this exogenous change in the built environment on violence. Neighborhood conditions and violence were assessed in intervention neighborhoods (n = 25) and comparable control neighborhoods (n = 23) before (2003) and after (2008) completion of the transit project, using a longitudinal sample of 466 residents and homicide records from the Office of the Public Prosecutor. Baseline differences between these groups were of the same magnitude as random assignment of neighborhoods would have generated, and differences that remained after propensity score matching closely resembled imbalances produced by paired randomization. Permutation tests were used to estimate differential change in the outcomes of interest in intervention neighborhoods versus control neighborhoods. The decline in the homicide rate was 66% greater in intervention neighborhoods than in control neighborhoods (rate ratio = 0.33, 95% confidence interval: 0.18, 0.61), and resident reports of violence decreased 75% more in intervention neighborhoods (odds ratio = 0.25, 95% confidence interval 0.11, 0.67). These results show that interventions in neighborhood physical infrastructure can reduce violence.

Using remote sensing to assess the relationship between crime and the urban layout

“…Cerdá et al (2012) found reduced violence outcomes in some neighborhoods of Medellin, Colombia, that were the focus of an urban development plan that included a transportation system and public space improvements such as additional lighting, new pedestrian bridges and street paths, a library park, and buildings for schools and recreational centers. Vegetation measures and land use diversity indices in those works were derived from remote sensing imagery, and the spatial pattern descriptors were computed from expensive and time-consuming field surveys and appraisals.…”

A Consensus-Driven Agenda for Emergency Medicine Firearm Injury Prevention Research

“…113 However, prior efficacy studies among youth at risk for violence have not led to concurrent work focused on how to prevent firearm injury among the similar populations. Further research is also needed to understand the specific impact of community-level interventions, such as improving neighborhood infrastructure 114 and community-based violence interrupter programs, [115][116][117][118] on firearm assaults and therefore on ED visits. 119 Mass Violence (Table 5) Mass firearm violence is distinct from other forms of firearm injury and death.…”

Transport engineering and reduction in crime: the Medellín case

“…This is demonstrated in a study carried out by researchers at the University of Columbia (US), published in the prestigious American Journal of Epidemiology. The article, entitled Reducing Violence by Transforming Neighborhoods: A Natural Experiment in Medellín, Colombia (Cerdá et al, 2012), compares the decline in violence between 2003 and 2008 in neighbourhoods 1 and 2 ("intervention neighbourhoods") compared with other CIT2016 -XII Congreso de Ingeniería del Transporte València, Universitat Politècnica de València, 2016. DOI: http://dx.doi.org/10.4995/CIT2016.2016 .…”