Although data can be a powerful tool in the argument over policies to address gun violence, approaches to collecting and using data across local police departments are inconsistent.
A call to the Erie Police Department comes back with the number of guns taken off the streets in the last few years. The Philadelphia Police Department releases annual reports on its website that show the number of shooting victims and homicide by firearm. In Reading, they're focusing on the locations of verified shots fired in the city.
Each police force collects a lot of the same information, but they can highlight specialized information that they think gives the best picture of what's going on in their respective communities. That's not uniform across municipalities.
The only place for detailed picture data on crime in the United States is the FBI's Uniform Crime Reporting system, or UCR. However, some say it's not the best system, because each state and municipality has its own standards for reporting crimes (making it, in fact, not so uniform). For example, an aggravated assault in one jurisdiction might be called a simple assault in another.
In Lancaster, Lieutenant Todd Umstead started keeping a running total on a notepad by his desk of the number of people actually hurt in shootings, because that wasn't clear just by looking at the UCR. Umstead said he realized this after a reporter came looking for statistics on shootings in the city, and the number recorded seemed much too high.
"If someone shoots a gun towards a car that has four occupants in a car and nobody's hit, nobody's injured, that counts as four aggravated assault [with a] firearm," Umstead explained. "I don't really consider that a shooting. I don't think the average person would consider that a shooting, because no one was actually shot."