Friday, June 8, 2018

Predictive policing to deter crime

From the Economist Technology Quarterly,
Crime does not occur randomly across cities; it tends to cluster. In Seattle, for instance, police found that half of the city’s crime over a 14-year period occurred on less than 5% of the city’s streets. The red squares in Foothill district cluster around streets near junctions to main roads—the better to burgle and run while homeowners are at work—as well as around businesses with car parks (lots of inventory, empty at night) and railway stations. Burglars who hit one house on a quiet street often return the next day to hit another, hence the red squares.
The reference is to PredPol, a leading crime prediction software, which is used in Foothill and other districts across the LAPD, and each red square represents 2.3 hectare.  

Such algorithmic applications have two use cases - one to monitor the policeman's performance by measuring arrests and other specific actions, and second to deter crime by increasing surveillance and patrolling in high-risk areas. 

It may be the second use case that carries greater relevance for police districts in developing countries. Instead of focusing on punitive actions and personnel performance management, supervisory officials could focus attention on whether resources are being deployed in line with the diagnosis generated by the algorithms so as to deter crime. While the counter-factual of crime prevented is not easy to comprehend or communicate, this is a more sustainable and appropriate approach to using such applications, especially in the early stages.

I am reminded of the story of the Municipal Commissioner who used a similar approach to get the public health staff to keep the city clean. Sanitation in cities is critically dependent on night-sweeping of main roads and early morning garbage lifting, and cleaning of roads and open drains. It is therefore a practice for good Municipal Commissioners to make early dawn surprise rounds of the city streets. Though the Commissioner rarely ventures out of his car during the couple of hours of morning rounds, the likelihood of a surprise round by the Commissioner (or his/her easily recognisable car) has a powerful effect in keeping the public health workers on their toes.

Some of the more enterprising Commissioners, instead of waking up early in the morning, would send out just their vehicles with instructions to the driver to randomly cover a few streets! The galvanising effect was just as same! The same could apply to Police Commissioners making surprise night patrols. Anecdotally at least, in weak capacity systems, one could argue that Commissioners (Municipal and Police) who make shirking and non-compliance costly are among the most effective officers.

Signalling and deterrence are powerful forces in disciplining weak capacity systems and keeping order.

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