These units can be individual suspects or offenders, people, places, neighborhoods, times of day, gangs, or even police officers or judges.
Some date the start of experimental criminology to the Cambridge Somerville Youth Study in Massachusetts in the 1930s, when 506 boys aged 5 to 13 were paired and randomly assigned to receive a multi-year program of support.
The policy impact and scientific attention given to the Minneapolis Domestic Violence Experiment and its five replications, while subject to controversy, is described by Australian Member of Parliament Andrew Leigh in his 2018 Yale University Press book entitled RANDOMISTAS: HOW RADICAL RESEARCHERS CHANGED OUR WORLD.
Sherman went on to lead or design over 40 randomized experiments with police in the US, Australia and UK, and to found the Academy of Experimental Criminology in 1998 as its first President.
The field of experimental criminology grew significantly during the 1990s and early 2000s, resulting in the establishment of the Crime and Justice Group of the Campbell Collaboration and other influential organizations, such as the societies of Evidence-based policing in five countries.