An Epidemiological Approach to Crime

October, 2015

A good friend of mine who is quite familiar with crime and criminal justice alerted me to this article that appeared in the October, 2015 issue of “Scientific American.” 

While I am more familiar with Deming’s system-thinking, data-based decisions, and continuous improvement than evidence-based policing, I can assure you that some hybridization with these principles will be part and parcel of 21st century policing. 

  • Professionals have a body of knowledge, it’s about time policing did, too!

The Article in Brief

  • An epidemiological approach of data analysis can reveal the root causes of violence and the best steps to curtail it.
  • In Cali, Colombia, the method reduced homicides from 124 per 100,000 inhabitants to 86 in just three years. In Bogotá, the rate dropped from 80 to 20 over nine years.
  • Changes in gun and alcohol laws were crucial. So were increasing police presence and giving youth social activities and jobs.
  • Today numerous cities across the Americas hold regular meetings of all crime agencies to analyze data, plan interventions and evaluate them.


    An Antidote to Murder: Exploiting Science to Reduce Homicide

    By Rodrigo Guerrero Velasco

“Violence is a big problem in modern society and in cities in particular. Homicides were rampant in my hometown of Cali, Colombia, when I became mayor in 1992. Few people saw murder as a pressing health problem, but I did—probably because I had earned a Ph.D. in epidemiology at the Harvard School of Public Health. I decided to apply the statistical methods used by public health experts to identify the sources of homicide and to reveal social and policy changes that might make a difference.

“At the beginning of my first term, the people of Cali and all of Colombia generally believed, mistakenly, that little could be done because we Colombians were ‘genetically violent.’ Other skeptics maintained that violent crime would not diminish unless profound changes were made on socioeconomic issues such as unemployment and educational levels. My administration and I proved all these people wrong.

“We developed an epidemiological database about the many societal factors that significantly raised the risk that a homicide would happen. These included sometimes subtle aspects of human behavior, such as the desire to carry guns in certain places or the tendency to drink alcohol on certain days. This exhaustive and fine-grained information led to new laws and policies built on data, not politics.

“The method worked. In 1994 annual homicides in my city, then home to nearly 1.8 million, dropped from 124 per 100,000 residents to 86 in just three years after the leading causes were found and policies were applied. An even larger decline took place over nine years in Bogotá, after our capital city adopted the same methods. And when I was elected mayor of Cali for a second time, in late 2011, after being out of office for almost 18 years, the same approach reduced homicide rates again. Let me tell you the story of how big data and scientific analysis can help solve entrenched social problems…

“Using an epidemiological strategy to help solve a social issue may seem straightforward, but it is not. The first lesson I can espouse is that such a move takes strong political will because the strategy frequently requires public officers to do things they would rather not do, such as making necessary but unpopular decisions to close bars or ban firearms. Making crime data public can also be uncomfortable, but it is essential, just as economists releasing unemployment and gross domestic product numbers is essential to formulating economic strategy. Data on social issues such as violence and education are now published periodically for various Colombian cities by nonprofit groups called ‘Bogotá How Are We Doing’, ‘Cali How Are We Doing,’ and so on. The information makes public officials and mayors accountable in their communities.

“The second lesson is that there is no one-size-fits-all approach in applying epidemiological methods to social issues because cities and countries have different risk factors. Data-driven observation is needed in each context to guide public officials.

“The process also requires perseverance and patience. Certain risk factors can be controlled rapidly—for example, by banning firearms or restricting bar hours—but other measures, such as improving the reach of police and judiciary services, take longer. Steps such as correcting social inequalities or establishing healthy child-rearing practices need not only time and patience but also considerable resources.

“Urban violence is socially regressive because it mostly affects the poor, and fighting crime devours a portion of the public budget, which could instead be invested to eradicate poverty. Violence prevention must therefore be a priority for humanity.”

Read the full article HERE.



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