Social networks can be part of more nefarious activities: sociologist Andrew Papachristos looked at two high-crime Chicago neighborhoods and found that a majority of the murders involved a small percentage of the population.

Papachristos looked at murders that occurred between 2005 and 2010 in West Garfield Park and North Lawndale, two low-income West Side neighborhoods. Over that period, Papachristos found that 191 people in those neighborhoods were killed.

Murder occasionally is random, but, more often, he found, the victims have links either to their killers or to others linked to the killers. Seventy percent of the killings he studied occurred within what Papachristos determined was a social network of only about 1,600 people — out of a population in those neighborhoods of about 80,000.

Each person in that network of 1,600 people had been arrested at some point with at least one other person in the same network.

For those inside the network, the risk of being murdered, Papachristos found, was about 30 out of 1,000. In contrast, the risk of getting killed for others in those neighborhoods was less than one in 1,000.

On one hand, this isn’t too surprising, especially considering the prevalence of gangs. At the same time, these numbers of striking: if a resident is in this small network, their risk of being murdered jumps 3000%.

I would be interested to know how closely the Chicago Police have mapped social networks like these. Do they use special social network software that helps them visualize the network and see nodes? Indeed, the article suggests the police are doing something like this:

Now, he wants to tap the same social networking analysis techniques that Papachristos, the Yale sociologist, developed to identify potential shooting victims, only McCarthy wants to use it to identify potential killers.

Police brass will cross-reference murder victims and killers with their known associates — the people projected as most likely to be involved in future shootings.

“Hot people,” McCarthy calls them.

Those deemed most likely to commit violence will be targeted first: parolees and people who have outstanding arrest warrants.

McCarthy said his staff estimates there are 26,000 “hot people” living in Chicago.

It would also be worthwhile to see how effective such strategies are. This isn’t the first time that organizations/agencies have tried to identify at-risk individuals. So how effective is it in the long run?