The numbers men of LA
March 31, 2013
The city’s police have found a way to spot trouble before it starts, writes Nick O’Malley.
The morning watch at the LosAngeles Police Department’s Foothill division begins at 6am, when the shift’s officers gather for roll-call and a briefing.
The dozen or so officers file into the roll-call room and find space on the benches. They are briefed on incidents from the previous shift, and on any offenders or vehicles they might be looking for. Then, before they hit the streets, each team is a handed a simple A4 map, warm from an office printer.
It doesn’t look like much, but the maps are the result of more than half a decade’s work by anthropologists and pure and applied mathematicians from two leading American universities, funded by supporters including the US Army and Navy.
Marked on the maps are a series of little red boxes outlining 150-metre-long squares superimposed over the streets they will patrol through the shift. The boxes indicate, with spooky accuracy, where the division’s most common crimes are most likely to be committed during the 12-hour shift.
The Predictive Policing project, or Pred Pol, as it has become known, has been so successful in cutting crime rates since it was tested in Foothill in 2011 that it has spread to seven other LA police divisions, with more to come. Another 20 or so police departments across the US have signed on, as have departments in Britain.
It is understood at least one Australian force is in talks to sign up, though its creators decline to discuss potential customers.
One of the driving forces behind Pred Pol is Dr Jeff Brantingham, an anthropologist at the University of California, Los Angeles (UCLA), who struggled bravely to find simple-enough language to describe the science behind the technology.
Crime prediction is not a new field. All street cops know the crime hot spots on their beat, and larger police forces have been employing crime analysts and software to assist them for years. It has been successful, too. The standard measure of accuracy for crime prediction is multiplications of random. Current techniques are usually effective about three times random. Pred Pol is twice as effective, accurate to six times random. And it is likely to improve.
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