University Times

Crime analysis may be elementary to Sherlock Holmes, but with homicide statistics, the FBI turned to a Pitt professor for help.
One project of the Visual Information Systems Center (VISC) at Pitt’s School of Information Sciences (SIS) is the creation of a system to aid the FBI in analyzing homicide data.
“Every year, the FBI puts out a huge book recording every homicide committed in the United States called the Supplemental Homicide Report, which nobody reads, but they do it because they’re required to by Congress,” said Ken Sochats, SIS faculty member and director of VISC. “Basically, they update the tables every year, with little or no analysis.”
The information on each homicide includes hundreds of elements:
the type of crime, race, age, gender of the victim and of the offender, the relationship between the victim and the perpetrator (an intimate, an acquaintance, a stranger), the weapon or weapons, the circumstances, where the crime was committed, time of day, demographics, whether there was one or more victim, and so on.
VISC developed an information system for the FBI that allows the user to pull any or all of these elements for visual comparisons, including from different years.
“Whatever element or elements I want to look at, I can drag and drop those onto a blank screen, at the user’s choice,” Sochats said. “We view the user as an expert who knows the domain, so in essence the visualization represents a hypothesis.”
In the diagram here, Sochats selected a comparison of homicides involving either whites or blacks or both (while eliminating other races), with data from 1991, the year with the most murders per capita in U.S. history, and 2000, the year with the least number of homicides per capita.
“Let’s say my hypothesis is that most murders are either blacks killing whites or whites killing blacks,” he said. “I’ve gone in and selected white victim, white offender, black offender and black victim for the two years. The system takes each murder and plots it as a dot.”
In the blink of an eye, all the sought-after homicides are plotted as dots in a circle. The clear conclusions include that the hypothesis is incorrect, because more murders are between the same race rather than inter-racial; that murder declined significantly between the two charted years in all combinations, and that reductions in the number of murders was greater among blacks.
Incidentally, the “outlying dots” are not dirt specks; they represent murders where the race of either the offender or the victim is known, but not both, or where there were murders with multiple victims or offenders of multiple races. The individual circumstances can be determined by clicking on the dot (or any plotted dot for that matter), which takes the user to the original report of the crime.
“With just a few simple drags and the push of a button, you can explore possibilities all over the place,” Sochats said.
-Peter Hart
As Shakespeare wrote in “Hamlet,” “Murder, though it have no tongue, will speak/With most miraculous organ.”