Evidence vs. Professional Judgment in Ranking “Power Few” Crime Targets: a Comparative Analysis

How accurately can local police officers use professional judgement to identify the highest-crime street locations and offenders with the most crime and harm, in comparison to an evidence-based rank-ordering of all possible locations and names derived from police force records? A face-to-face survey was conducted in groups with a purposive convenience sample of 123 operational police officers to ask their professional judgement for selecting the ten most crime-prone streets and suspected offenders in their command areas. Separate rankings by crime harm were also requested. Cambridgeshire Constabulary crime and confirmed suspect reports were analysed to create the same lists the officers were asked to provide. The study compared results of surveys of police officers asked to name the top 10 streets and offenders for volume and harm of crimes committed in each policing area to the top ten lists generated by comprehensive and systematic analysis of reported crimes. The top ten lists generated by officers were highly inaccurate compared to the lists produced by comprehensive analysis of crime and charging records. Officers surveyed were 91% inaccurate in naming the most prolific suspected offenders in their areas and 95% inaccurate in naming the most harmful suspected offenders. Officers were slightly less inaccurate in naming the streets in their areas with the highest frequency of crimes (77% incorrect) and the greatest severity of crimes (74% incorrect). Officers in urban areas (N = 42) were substantially more accurate than officers working in semi-rural areas (N = 30) in identifying streets with the highest crime frequency (Cohen’s d = 0.9; p = .00) and highest total harm (Cohen’s d = 1.3; p = .00), but urban officers still failed to name about two-thirds of the most harmful streets. Police officers can benefit from evidence-based targeting analysis to help them decide where their proactive and preventive work can be deployed with the greatest benefit.