(Phoenix) April 5, 2017 - One of the most hotly contested debates today involves the recent uptick in violent crime and the extent to which increases in violence may be explained by the "Ferguson effect," whereby the increased scrutiny of police since the 2014 Ferguson unrest has been hypothesized to lead police officers to become more hesitant and less aggressive. Chicago is an epicenter for much of this controversy, and on numerous occasions President Trump has threatened to "send in the feds."

In an article published today in Significance, the official magazine and website of the Royal Statistical Society (RSS) and the American Statistical Association (ASA), Arizona State University professors Sherry Towers and Michael D. White examine violence in Chicago and test whether the trends are consistent with the "Ferguson effect." They also test a competing claim proposed by Former NYPD Commissioner William Bratton that much of the recent violence in Chicago is tied to the proliferation of guns in that city.

Towers and White found no evidence of a Ferguson effect in Chicago.

"Murders and gun assaults in Chicago began increasing before Michael Brown's death in Ferguson," says Towers, a research professor in the Simon A. Levin Mathematical and Computational Modeling Sciences Center at Arizona State University in Tempe.

They did find a strong association between firearms availability and gun violence in Chicago, supporting Commissioner Bratton's argument.

"Our analysis highlights the importance of including measures of firearms proliferation when studying trends in violence in Chicago and elsewhere," says White, a policing expert and professor in the ASU School of Criminology and Criminal Justice in Phoenix.

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