STEVE INSKEEP, HOST:
Visit any city and people are going to tell you that some parts of town are at higher risk for crime. That's a bad neighborhood, they might say; there's more gun violence there, more assaults, more homicides. And if you look at statistics ZIP code by ZIP code, that seems to be true. But there's new research that suggests we are not really seeing what's going on. NPR's social science correspondent Shankar Vedantam joins us each week on the program. He's here with some new research about Chicago. Hi, Shankar.
SHANKAR VEDANTAM, BYLINE: Good morning, Steve.
INSKEEP: OK. So what are we missing when we think about high-crime neighborhoods?
VEDANTAM: You know, we might be missing the wood for the trees, Steve. So take Chicago, for example, in the example you just gave about the ZIP codes. If you visit the website of a newspaper, like The Chicago Tribune, it will tell you that you have a high risk of becoming a victim of violent crime if you live in a neighborhood such as Washington Park or Fuller Park. But not everyone in these neighborhoods is actually equally at risk for becoming a victim of violent crime. I spoke with Andrew Papachristos. He's a sociologist at Yale, and along with Christopher Wildeman, he found the real risk doesn't lie at the level of neighborhoods, but at the level of a network with in the neighborhood. Here he is.
ANDREW PAPACHRISTOS: What you see is that being in this network, this small network of 4 or 5 percent of the population, increases your risk of being a homicide victim by 900 percent.
INSKEEP: Nine-hundred percent? Wait a minute, OK, so a network - just a group of people who live in different places, but they're connected in some way. If you're in that network, you're at a huge risk for being a homicide victim. If you're living right next door, but not in that person's network, you're a very low risk.
VEDANTAM: That's exactly what Papachristos is saying. He's finding that 41 percent of all gun homicide victims occur within a group that's 4 percent of the population.
INSKEEP: Wow. So what puts me in the high-risk group?
VEDANTAM: Well, I should start by saying Papachristos is not talking about a network like a gang where people are actively organizing one another. He's talking about people connected through social relationships, very much like Facebook. I have friends, and I friends of friends, and I have friends of friends of friends. In Chicago, your risk of becoming a victim of homicide seems to depend on your location within a network of co-offenders. Let me explain that for just a minute. Let's say you and I commit a crime together, Steve.
INSKEEP: Sounds like fun.
VEDANTAM: That would link us in the database as being co-offenders. Now tomorrow, let's say you and David Greene were to commit a crime together. That would not only link the two of you as co-offenders; it would link me with David Greene.
INSKEEP: Even if you'd never had any contact with David Greene?
VEDANTAM: Exactly, so but in this network, I'm basically one step away from David Greene, and you're the bridge between us. What the analogy is basically suggesting is if I get killed, that not only places you at higher risk of becoming a victim of homicide, but it places David Greene at higher risk as well because he's connected to me through you.
INSKEEP: What is it that authorities can do with this information exactly?
VEDANTAM: Well, the hope is to use this information to serve public health goals. So in other words, if you think about this information as identifying the people who are at higher risk, one potential application is that you can go up and tap people on the shoulder and say, you might not recognize that you're part of this network, or you might not recognize you're at a position of this network that places you at higher risk, but we're telling you about that. And you need to take steps to protect yourself. If you think about it, Steve, this is a public health model that's very similar to the way we fight infectious diseases, and in fact Papachristos thinks that homicide not only functions very much like an infectious disease; it functions like a very particular kind of infectious disease. Here he is again.
PAPACHRISTOS: Gun violence is much more like a blood-borne pathogen. It tends to be very specific behaviors - risky behaviors - that put you in these networks. And in some ways, it becomes much more like the spread of diseases through needle sharing or unprotected sex, rather than catching a bullet from somebody sneezing.
VEDANTAM: I should say, Steve, that this research trying to find out if you can tap people on the shoulder and protect them from homicide is still in its early stages. We don't have evidence yet that it's actually going to lower the homicide rate, but down the road that's the hope.
INSKEEP: Shankar, thanks very much.
VEDANTAM: Thank you, Steve.
INSKEEP: NPR's Shankar Vedantam. You can find him on Twitter @HiddenBrain. And as always, you can find this program on Twitter at @MorningEdition, @NPRInskeep and @RachelNPR. Transcript provided by NPR, Copyright NPR.
