Experimental criminology is a field within criminology that uses scientific experiments to answer questions about crime: its prevention, punishment and harm. These experiments are primarily conducted in real-life settings, rather than in laboratories. From policing to prosecution to probation, prisons and parole, these field experiments compare similar units with different practices for dealing with crime and responses to crime. These units can be individual suspects or offenders, people, places, neighborhoods, times of day, gangs, or even police officers or judges. The experiments often use random assignment to create similar units in both a "treatment" and a "control" group, with the "control" sometimes consisting of the current way of dealing with crime and the "treatment" a new way of