It’s often difficult to certify whether gun violence is directly related to gang retaliation, although police can draw conclusions on the circumstantial basis of the victim’s history and the neighborhood where the crime occurred, cautions James Alan Fox, a criminology professor at Northeastern University in Boston.
“It’s speculation,” Mr. Fox says. “But what we can do is identify neighborhoods where homicides occur as those that tend to be where gangs flourish. Not all these homicides are gang-related, but it’s clear some of them are.”
For example, a killing that starts with a teenage argument over a girlfriend is often categorized, mistakenly, as gang-related because one of the teens happens to be in a gang. Youth homicide is often “in the gray zone when you have a lot of gang-affiliated youth who are having teenage disputes,” says Harold Pollack, a co-director of the University of Chicago crime lab, which analyzes crime data for the police and for research.
At least 200 homicides took place in Chicago since the first of the year, a jump from the 134 in 2011 during the same period. Police data show that shootings are also up 14 percent over last year: 851 so far in 2012 compared with 747 in 2011 through late May.
Comparisons of homicide statistics at midyear are often problematic, because they don't account for factors such as weather, says Fox. Comparing current year data with a previous year's data can also be misleading, especially if the previous year reflected a dip in the rate of violence.
Assessing whether Chicago's new strategies are working is a long-term prospect, mostly because homicide statistics are prone to short-term variability, says Mr. Pollack.
“There are going to be periodic fluctuations in homicides that don’t really tell us these policies are working or not. The question will be the quality of execution and whether the size or complexity of Chicago means some of these strategies have to be modified to fit our conditions,” Pollack says. “We have to approach this in the long run rather than the short run.”