Visitors contribute to rise in the crime rates of cities

“When we look at crime rates, we forget that people move, that people are visitors of other areas all the time,” said Boivin, himself an “outsider” to Montreal (he lives on the city’s South Shore and commutes to work at the university) and also an “insider” with the city’s police force (he worked there as an analyst until 2012 while doing his Ph.D.).

“Our new study is unique in two ways,” Boivin said. “The first is that we had very detailed data from the police; having the location of crime incidences is not rare, but having the home address of offenders is. The second is we use transportation data, which is something that’s not widely available; only four other Canadian cites collect it.”

What did they learn?

“Our main finding, if I had to just sum up in one sentence, is that visitors matter. We need to know more about visitors to better understand crime, and the good news is that we are learning more, from social media and other sources. Visitor data is increasingly available, and our paper is just one of the first on the subject.”

“A boom in criminology”
One other surprising finding: Not only do parts of the city with high numbers of visitors also have higher crime rates by both visitors and residents, there’s also more violent crime in areas that have what Boivin calls “an unstable population,” places where there’s a high number of recent arrivals, over the last five years or less.

Violent crimes include homicide, sexual and non-sexual assault, robbery and kidnapping; property crimes include breaking and entering, various forms of theft, and fraud. Most violent crimes have a high “clearance rate,” meaning a suspect is charged or identified; in Montreal, the rate in 2011 was 63 percent. Property crimes, by contrast are rarely cleared: in Montreal in 2011, the rate was only 12 percent. Boivin anticipates “there will be a boom in criminology as new data become available,” and hopes that more research will buttress his finding that mobility is just as important for property and violent crime as the usual factors related to “social disadvantage” in cities: how many single-parent families live in an area, how many visible minorities, how many recent arrivals, how many low-income households.

Twitter data coming next
Two further studies are coming this year from Boivin and colleagues at UdeM:

— The first, co-authored with Patricia Obartel, looks at the relationship between visitor inflows to Montreal and the police’s use of force between 2008 and 2011. The paper has been accepted for publication in the CJCCJ.

— The second involves Twitter. Boivin and criminologist Francis Fortin are looking at where tweets are sent from and how they might relate to crime trends; the scholars plan to submit their findings for publication this summer.

The Twitter data, all publicly available, could prove to particularly rich in information.

“Transportation survey data is not that specific; we don’t really know precisely where people are, just where they say they’ve been,” said Boivin. “Twitter data is something else entirely. They have x/y coordinates, so we can know exactly where people are, as close to five meters away. We can look at the content and see if and how it relates to patterns in crime.”

— Read more in Rémi Boivin and Marcus Felson, “Crimes by Visitors Versus Crimes by Residents: The Influence of Visitor Inflows,” Journal of Quantitative Criminology (2017) (DOI: 10.1007/s10940-017-9341-1)