Researchers have long known that bigger cities disproportionately generate more crime. Now a new study from Northwestern University and the Santa Fe Institute explains why: It’s easier for criminals to find collaborators.
“In a big city, you have the potential to meet more distinct people each day,” said Northwestern’s Dr. Daniel Abrams, senior author of the study. “You’re more likely to find an appropriate partner to start a business or invent something. But perhaps you’re also more likely to find the partner you need to commit a burglary.”
The study was published on September 17 in the journal Physical Review E.
As cities grow, crime grows even faster. And certain types of crime — such as robbery, car theft and murder — exponentially outpace the population.
To learn why, Dr. Abrams and Dr. V. Chuqiao Yang collaborated with Northwestern sociology professor, Dr. Andrew Papachristos, who studies social networks in urban neighborhoods. The researchers developed a new mathematical model that predicted the number of crimes as a function of social interactions.
To do this, they used data from the FBI, Chicago Police Department and the National Incident-Based Reporting System. The team was specifically interested in co-arrest records — or records in which multiple people were arrested for the same crime — across seven categories: robbery, motor vehicle theft, murder, aggravated assault, burglary, larceny-theft and rape. Of these categories, only rape grew linearly, at roughly the same pace as a city’s population. The other crimes are more “social” in nature and often require a team effort.Friday Letter Submission, Publish on September 27