Why is a true experimental design the strongest method for conducting impact evaluations?

Question

What will be an ideal response?

Answer 1

Problem-oriented policing strategies are increasingly used by urban jurisdictions to reduce crime in these high-activity crime places. Problem-oriented policing challenges officers to identify and analyse the causes of problems behind a string of criminal incidents. Once the underlying conditions that give rise to crime problems are known, police officers can then develop and implement appropriate responses. One of the only true experiments to examine the efficacy of problem-oriented policing was conducted by Anthony Braga and his colleagues (1999), and it still remains a model evaluation study today. These researchers created a novel field experiment to determine the effectiveness of problem-oriented policing in decreasing the rate of violent street crime in Jersey City, New Jersey. Recall from Chapter 6 that a true experiment allows researchers to assume that the only systematic difference between a control and an experimental group is the presence of the intervention, in this case, the presence or absence of problem-oriented policing strategies.
To determine which places would receive the problem-oriented strategies and which places would not, 56 neighborhoods were matched into 28 pairs with equal levels of crime, which were then randomly assigned to receive the problem-oriented policing treatment (experimental places). Remember that a key feature of true experimental designs is this random assignment. The places that were not selected from the flip in each pair did not receive the new policing strategies (control places).
Random assignment ia procedure by which each experimental and control group subjects are placed in a group randomly.
In each of the experimental places, police officers from the Violent Crime Unit (VCU) of the Jersey City Police Department established networks consistent with problem-oriented policing. For example, community members were used as information sources to discuss the nature of the problems the community faced, the possible effectiveness of proposed responses, and the assessment of implemented responses. In most places, the VCU officers believed that the violence that distinguished these places from other areas of the city was closely related to the disorder of the place. Although specific tactics varied from place to place, most attempts to control violence in these places were actually targeted at the social disorder problems. For example, some tactics included cleaning up the environment of the place through aggressive order maintenance and making physical improvements such as securing vacant lots or removing trash from the street. The independent variable or treatment, then, was the use of problem-oriented policing, which comprised a number of specific tactics implemented by police officers to control the physical and social disorder at experimental violent places. In contrast, control places did not receive these problem-solving efforts; they received traditional policing strategies such as arbitrary patrol interventions and routine follow-up investigations by detectives. No problem-oriented strategies were employed.