Papachristos constructs a social network—not a virtual one in the Facebook sense, but a real one of social connections between people—by looking at arrestees who have been arrested together. That turns out to be a lot of people in raw numbers, almost 170,000 people with a “co-offending tie” to one another, with an average age of 25.7 years, 78.6 percent male and 69.5 percent black. It’s also a large percentage of all the individuals arrested: 40 percent of all the individuals arrested during that period.Within the entire group, the largest component of that whole co-offender group has 107,740 people.
Within the timeframe—from 2006 to 2010—70 percent of all shootings in Chicago, or about 7,500 out of over 10,000, are contained within all the co-offending networks. And 89 percent of those shootings are within the largest component.
Or, to put another way: the rate of gunshot victimization (nonfatal + fatal) in Chicago is 62.1 per 100k. Within a co-offending network, it’s 740.5—more than 10 times higher.
This sounds very similar to his research on murders: being part of a particular social network dramatically increases the risk of being part of a shooting. One implication is gun crime in Chicago isn’t simply about being in a disadvantaged neighborhood or in the wrong place at the wrong time; it is about how you are tied to other people.
The article goes on to an interesting interview where Papachristos talks about data issues (collecting the right data, being able to put it into network form) and translating findings such as these into policy choices.