Evidence-Based Policing Matrix
Micro Places – Weiss & Freels (1996)
Weiss, A., & Freels, S. (1996). The effects of aggressive policing: The Dayton traffic enforcement experiment. American Journal of Police, 15(3), 45-64.
Location in the Matrix; Methodological Rigor; Outcome:
Micro places, General, Proactive; Moderately Rigorous; No evidence of an effect
What police practice or strategy was examined?
This study tests the impact of aggressive traffic enforcement on serious offenses, arrest for serious offenses, arrests for drug, weapon and driving under the influence, and traffic accidents. Officers in the experimental areas were encouraged to write traffic citations as well as increase the number of stops. Officers were told to make the stops in locations easily visib le to other motorists and to activate their emergency lights.
How was the intervention evaluated?
Researchers asked the Dayton Police Departments to identify six to eight potential intervention areas that had a high volume arterial street with a mix of commercial and residential property; that had been relatively stable over time with regard to crime; and that had experienced substantial levels of crime and traffic accidents. The sites were also not adjacent to each other. From these potential sites, one area was randomly selected as the experimental area to receive aggressive traffic enforcement while another was randomly selected as the control area (no change in police activity). Data were gathered on treatment measures, crime incidents, arrests, and accidents. Prior to the experiment, police patrol officers in Dayton did not tally the number of traffic contacts made on each shift, so it was necessary to add a response category to the officer’s daily activity reports to record this data.
What were the key findings?
Increased traffic enforcement did not reduce the incidence of either robbery or auto theft and did not affect arrests for index offenses. In addition, increased traffic law enforcement did not have any detectable effect on reported traffic accidents when comparing the treatment with the control area. There was also a statistically significant reduction in arrests for drugs, weapons, and DUI offenses.
What were the implications for law enforcement?
This study provides no clear evidence that providing more traffic enforcement will reduce crime, contradicting two earlier studies (Sampson and Cohen, 1988; Wilson and Bolan, 1978). The authors suggest that there are three reasons why this study may have failed to detect a relationship between traffic enforcement and crime: the absence of such a relationship, insufficient level of treatment, and inadequate statistical power.
Where can I find more information about this intervention, similar types of intervention, or related studies?