An attempt to use software to help prevent gun crime in Chicago did not save lives, according to a study.
In 2013, the city’s police began using algorithms to create a list of people deemed to be most at risk of being shot dead. But the effort had no impact on homicide rates, the report said. Rather, those on the list were more likely to face arrest themselves.
The police defended the tech saying its predictive power has since improved.
The report was carried out by the Rand Corporation, a public policy-focused research body, and was published in the Journal of Experimental Criminology.
Both the police and the software’s developer – the Illinois Institute of Technology – co-operated with Rand’s evaluation.
The so-called “predictive policing” initiative was based on the idea that potential victims of gun crime could be identified by building a social network model.
Specifically, the software calculated a person’s risk factor on the basis of two variables:
- how many times they had been arrested with others who had later themselves become gun crime victims
- the number of relationships they had to intermediaries who had been arrested with people who had become homicide victims
This resulted in a total of 426 people being identified as “high risk” in March 2013. They were placed on a register called the Strategic Subjects List (SSL).
The researchers said their analysis of the gun crime that followed indicated that being on the list made no difference to people’s chances of being shot or killed. Neither was there any impact on overall homicide levels, they added.
But they said the SSL’s members became more likely to be arrested for the shootings of others.
“The effect size was rather large… 2.88 times more likely than their matched counterparts,” the study said.