See page #27: https://portal.chicagopolice.o...
It's also important to remember that not all inner city gun violence is officially "gang-related" (as in, involved someone who was ACTUALLY a member of MS-13 or some other Gang (capital "G") that's being followed by the researchers). Here in the Baltimore Metro area, the rate of handgun violence is orders of magnitude higher in the city compared to the surrounding suburbs, and the motives are almost always drug-related (even if those involved weren't actually part of an official "gang"). Of course, both Chicago and Baltimore have some of the strictest gun laws in the country . . . clearly the answer is to tighten those even further and ignore the root causes of the violence.
The only possible interpretation of any research whatever in the `social sciences' is: some do, some don't. -- Ernest Rutherford