UCL Department of Security and Crime Science

The police targeting of stop and search

Dates: 2005 and 2006, and to 2012 (date of NPIA publications)

Staff: Spencer Chainey

The research was conducted in two parts - further details below. Some of the main results of the work are captured in these two publications:

Chainey, S.P. and McDonald, I. (2012). Stop and search, the use of intelligence

and geographic targeting. Full report. London: National Policing Improvement Agency.

Chainey, S.P. and McDonald, I. (2012). Stop and search, the use of intelligence

and geographic targeting. Briefing note. London: National Policing Improvement Agency.

We also carried out research into the following and hope to publish separately on these in 2013:

• A local level spatial comparison of stop and search and its impact on arrests
• The application of geographical analysis techniques for comparing spatial distibutions of stop and search, and the crime they relate to
• The use and impact of Section 60 stop and search notices on crime
• The relationship between stop and search and pedestrian flows

Core Research

This research explored the geographic and temporal targeting of search activity.  It explored patterns of search activity at the local level to answer the following main questions,

• Are searches geographically and temporally concentrated?
• What effect does the geographical and temporal targeting of search activity have on its effectiveness and how it impacts on crime?
• Is the geographic targeting of searches applied proportionately (in relation to crime levels and other intelligence, and by demography)?

The research used recorded crime, incidents, and stop and search data from five police forces (Cheshire, Hertfordshire, Merseyside, the Metropolitan Police and West Midlands).  These data was subject to an extensive data cleaning process before the research commenced in order to make them fit for purpose for the analytical tasks conducted.

The research not only explored the use of stop and search under PACE, Misuse of Drugs Act and Firearms Act, but also in relation to Section 60 Criminal Justice and Public Order Act 1994 (as amended by s8 of the Knives Act 1997),  and the Terrorism Act 2000.

Developmental Research (conducted in partnership with Intelligent Space)

The Developmental Research into the police targeting of stop and search provided the first large-scale study on the relationship between pedestrian flows and the levels of searches and crimes. This study analysed searches and specific crime types in order to explore the relationship between search activity, crimes and on-street pedestrian levels.  Crime types that were selected and aggregated into a ‘crime’ dataset were drugs offences, robbery, theft from the person, and weapons offences.  These crime types were consistent with offence groups analysed in the Core Research.

Temporal and spatial analyses of searches, crimes and pedestrian flows were carried out for the police Basic Commands Units (BCUs) of Lambeth and Westminster in central London. A large resource of pedestrian flow counts was used to create a database that linked 60,000 searches, 7200 crimes, and 266 flow count locations onto 8700 streets.

Temporal models of pedestrian flows were used to calculate annual movement volumes for all linked streets and enable direct comparisons between streets. More comprehensive analysis of 24 hour movement was undertaken for several locations where continuous flow counts were available, to identify additional temporal variations.