A 2005 study led by Larry Bennett, a professor of social work at the University of Illinois at Chicago and an expert on batterer intervention programs, found that of the 30 batterer intervention programs in Cook County, Illinois, 15 percent of batterers who completed the programs were rearrested for domestic violence, compared with 37 percent of those who dropped out of the programs. However, Bennett said the studies are largely meaningless because they lacked a proper control group. He added that participants who complete domestic violence programs are likely to be more motivated than others to improve behavior and would be less inclined to offend again.