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Understand GPD


The Global Policing Database (GPD) is a world-first repository of policing evaluation research, developed specifically to support police practitioners and policy makers to translate research into evidence-based policing.

Evidence-based policing is an approach that brings together law enforcement knowledge and training with empirical research evidence, enabling fair and just reforms in policing that maximise efficiency. By accessing the best available research evidence on police and policing practices and interventions, police are better equipped to make decisions based on evidence of ‘what works,’ increasing the likelihood of fair and effective outcomes.

Globally, police organizations address a wide range of challenging problems. Local and global events create public scrutiny of policing, casusing a mounting push for evidence-based policies and policing practices. Evidence-based (and led) policing reform is now at the forefront of societal demands globally. Our communities call for policing agencies to use fair and evidence-based best-practice approaches, driving the need for police and policy makers to access a comprehensive and robust repository about what works in policing.

Ad hoc and online searches for policing-related research can generate huge amounts of information. Finding a reliable, consistent and easy to access repository of high-quality, impact evaluations of police and policing is like finding a needle in the haystack. Standard search engine queries lack scrutiny and assessments of relevance and quality. Academic database searches offer highly valuable full-text academic publications that often require pay-per-view access. Practitioner-led studies are even harder to locate sometimes found in the “grey literature” on government websites. All of these existing databases (e.g., ProQuest, EBSCO, Wiley online etc), search engines (e.g., Google Scholar) and grey literature sources (e.g., Crime & Justice Research Alliance, UK Ministry of Justice) contain very valuable information. The GPD uses all of these sources to bring together a comprehensive repository of high-quality police and policing evaluation studies.

The GPD offers a global resource to connect police policy makers and practitioners with high-quality evaluation research to help guide development and implementation of evidence-based policing. 



The GPD is a web-based searchable bibliographic database, capturing published and unpublished experiments, quasi-experiments and reviews of police and policing interventions conducted since 1950. The GPD is unique because it has NO restrictions on the type of policing technique, type of outcome measure, and language for a study to be included in the GPD. The GPD captures evaluation research where police are implementers of an intervention (such as implementing organizational reforms, tactics focused on problem places or people, or police using new, innovative police technologies); or when police are participants in the research (such as testing new training programs); or when police are intervention partners (such as working with communities and other agencies). Measures of intervention effectiveness extend beyond crime and disorder outcomes to include all possible outcomes, including (but not limited to): citizen perceptions of police, fear of crime, police biopsychosocial wellbeing, organizational effectiveness, use of force, complaints and much more.

Every single harvested document in the GPD since 1950 is systematically screened to determine its relevance to police and policing and to ensure that it is a high quality impact evaluation of a police or policing intervention.

The GPD takes the hard work out of finding and accessing policing evaluation research. We have spent more than 10 years meticulously harvesting and searching 88 academic databases across multiple disciplines (criminal justice, psychology, economics, public health, medicine), 89 grey literature sources (mainly government websites from across the world) and 20 hand search sources (including harvesting all cited references from eligible evaluation studies). We are confident that the GPD eligible studies include a full and complete repository of high-quality impact evaluations from around the globe.


Many documents (media reports, academic articles, books, government reports, commissioned reports, theses) produced around the world refer to police and policing. But only a small portion contain high-quality research evidence evaluating police and policing interventions. The GPD team (comprising over 100 trained and paid staff as well as volunteer students) have followed a comprehensive searching and detailed screening methodology to carefully review nearly 300,000 harvested documents gathered since 1950 to the present time. Only evaluation research that meets our screening criteria make it into the repository of GPD eligible studies accessed via the GPD Website Portal.

What does “high quality” mean for research studies in the GPD?

  • Peer-reviewed papers
  • High quality non-peer reviewed, ‘grey literature’ reports
  • The study must contain a policing intervention (something police could actually implement or change, or is provided to police) — the intervention could be conducted in the field, in the lab or as a vignette in a survey
  • The study must contain a quantitative evaluation of the policing intervention(s) with a numerical measure of the impact when the intervention is present compared to when the intervention is not present (counterfactual).

How are the GPD eligible studies relevant to contemporary challenges in policing?

  • The publications contain information about a policing intervention and a measure of their impact (i.e. whether they have or have not ‘worked’)
  • The GPD eligible studies contain a variety of research on a wide range of topics, providing a basis for generating new ideas and responses to common crime and policing problems
  • The high quality of research evidence provides a justifiable basis for future decisions and plans
  • Studies in the GPD are all coded to include information about the country where the intervention was undertaken, the research design, type of intervention implemented and the outcome measures assessed.


Please click here to access the GPD methodology including information about our harvesting and screening methods.

Policing Intervention Categories

Interventions included in the GPD repository of eligible studies fall within one of these five categories.


Policing Practices

These include police-initiated activities, or interventions where the police are ‘doing the intervening.’ Also includes police as intervention partners, where the police seek to co-produce crime control by working with citizens, other public sectors, or private industry. These interventions examine policing practices such as hot-spot policing, problem-oriented policing (POP), order-maintenance policing, focussed deterrence, third-party policing (TPP) and community policing.

Investigative Techniques

These include different techniques police use to collect, study and evaluate crime evidence and information, including investigative interviewing, interrogation and forensic evidence gathering.

Police organizations, staffing, and training

These include activities relating to police staffing and features of policing organizations, such as employment, training, role capability, organizational structure, learning, and development. Studies in this category evaluate things like the impact of police department size on crime outcomes, human resource policies and their impact on officer wellbeing, and the health outcomes for police deployed on different shift rosters.

Police technologies and equipment

These include interventions testing tools, technologies and equipment commonly used by police such as technology or equipment used for the purpose of police protection and safety. This category of studies also includes Body Worn Cameras, Tasers, and police apparel (e.g., uniforms, or protective gear).

Legislative, regulatory, or policy reforms or changes

This category includes laws and legislation made and enforced by governments that dictate what police must do. This may include legislative, regulatory or policy reforms/changes affecting police powers.

Policing Intervention Glossary

Here are some of the policing interventions most commonly found in GPD repository of eligible studies.

Amber alerts / missing persons

Amber alerts and other missing persons alerts are police-initiated actions (generally, communications) that engage the public (or other agencies) to garner extended support in looking for missing persons.

Arrest - not further specified

Arrest is used as an independent variable in the study, and no further information or specification is given about the type or nature of arrest to sufficiently categorise it elsewhere.

Arrest - response to specific crime or event

Arrest is used as an independent variable, with specifications around the context, purpose (i.e. crime targeted) and/or type of arrests conducted.

Body-worn cameras

Body-worn cameras (BWCs) or body-worn videos are recording devices worn by police to capture events and interactions from the police’s viewpoint. They are deployed in a variety of ways (e.g., automatically and manually) and use can be mandated or encouraged by a range of stakeholders (e.g., policy, government, within-agency, other municipal groups).

Broken windows policing

An approach that prioritises the maintenance of neighbourhood order, and environmental factors, to reduce the potential for the environment to reflect a low standard of societal cohesion (as it is theorised that this encourages criminal activity).

Diversion, cautions or warnings

Police strategies to divert (potential) offenders from arrest, court, prison, offending, and recidivism.

Communication systems

Communication systems and channels used by police in the course of their regular work. Refers to systems used for communication between police and other professionals, not police-to-public. Includes police radio systems, interagency communications, triage protocols, etc. – e.g., TETRA (Terrestrial Trunked Radio Telecommunication systems). Does not include police-to-public communication (i.e. social media) or pedagogical approaches (e.g., the way training materials are ‘communicated’).

Community engagement

Includes police interactions and/or collaboration with community groups and subgroups, supporting civilian involvement in the regulation and enhancement of local areas.

Community policing

Policing strategies that prioritise police-community engagement and partnership, for collaborative solutions to problems.


Short for ‘Computer Statistics’, CompStat “is a performance management system” that uses jurisdiction-specific crime mapping to monitor police performance and delegate their efforts.

Crime mapping technology

Technologies and software used to analyse the location and characteristics of crime events to make predictions about the spatial nature of crimes and guide the development of targeted enforcement/intervention efforts.

Data collection

Police collection of data, which may be for research or intervention purposes – e.g., a study comparing the outcomes for police agencies that surveyed the public to gather community-specific data before implementing an intervention, and agencies that did not.

Disaster response

Management of, and preparation for, public disasters and emergencies. Includes police activities in response to large-scale disasters, such as flooding, fires, terrorist events, etc. Could include resource distribution, inter-agency collaborations, police management of the public, etc.

Evidence collection and presentation

Collection and presentation of facts, information, and objects related to criminal investigations. Could include physical (e.g., forensic) evidence and testimonial evidence (e.g., witness reports, suspect interviews, etc.). Opposed to forensic techniques, although more specifically relates to the methods of collection and presentation used by police, rather than evidence analysis or evaluative techniques. May include (but not limited to): Camera perspective when videoing interviews for use in court, providing videoed or written transcripts of interviews.

Evidence-based / Risk-focused policing

A preventative policing strategy that focuses on protective factors in reducing the likelihood of offending for high-risk groups.

Foot patrol

Officers doing rounds of their beat, or a specified jurisdiction, on foot. Can be indoors or outdoors.

Forensic techniques

Scientific examination of evidence related to crimes, for investigative purposes. Encompasses a number of tools, technologies, and approaches. For example, fingerprint detection accuracy, forensic DNA testing examples, etc. May overlap with ‘Evidence collection and presentation’ in some studies, although applies specifically to the analysis of forensic (physical) evidence, and may exclusively apply to some studies comparing technologies or techniques.

Hot spots policing

Police proactively focus resources on geographic locations that have been identified as high-crime areas (i.e., hot spots).

Intelligence-led policing

A proactive policing approach that centres the use of data and intelligence in strategic decision making, and sometimes the development of specialised tactical units or teams, for more targeted and efficient crime control.


A formal or informal interview conducted by police, for the purpose of eliciting and gathering information from an individual. Does not include studies where the interview has been used solely as a research methodology for data collection, as opposed to a component of the actual policing intervention.

Interview-related factors

These include features of interview rooms, separation of interviewees prior to interview, etc.


A type of eyewitness identification, wherein a suspect and ‘fillers’ (non-suspects) stand before a witness. The witness is asked to nominate the culprit, if they believe they are present in the line-up.

Neighbourhood watch

Organised groups of civilians coordinate to monitor their local areas for crime and vandalism, in cooperation with police.

Offender profiling

Analysis of criminal offender characteristics and case information, to identify patterns and commonalities. For example, use of assessment tools often used to predict and prevent crime patterns.

Order-maintenance policing

The management of minor offences and neighbourhood disorder, in line with broken windows theory, to reduce community level crime.

Police animals

Animals that are employed to assist police in their duties and law-enforcement activities. This could include (but is not limited to) police dogs (K-9) and horses. Police animals may be the participant of the study (if so, they are treated the same as human police participants).

Police apparel, uniforms and gear

Could include police uniforms, comparisons with plain-clothed police, or police protective wear.

Police health and wellbeing

Activities targeting police physical and psychological wellbeing.

Police job characteristics

Elements of police employees’ job tasks, organisation, and requirements. Includes rostering and shift length.

Police management and/or leadership

Police roles and competencies relating to the internal management and leadership of other police within a policing organisation.

Police recruitment and onboarding

Practices, processes and features of recruitment, selection and employment of police employees – e.g., education level of police, varied recruitment strategies, onboarding trainings, etc.

Police vehicles and transportation

Interventions relating to the vehicles and transportation used by police in conducting their duties and frontline service delivery.

Police weapon use

Activities relating to police access to, training in, and use of weapons for enforcement – e.g., guns, tasers, capsicum spray, etc.

Police-to-public media communication

Police use of public-facing platforms to communicate with citizens. Includes police websites and social media.

Predictive policing

The strategic analysis of crime data sets to guide the deployment of police.

Problem-oriented policing

A proactive policing approach, in which police use analytic and experimental approaches to reduce negative outcomes by focusing on the contextual factors and antecedents that contribute to their repeated occurrence. POP entails the identification and analysis of a specific crime problem to develop a targeted response.

Procedural justice

A method employed in interventions (usually named) which requires police-public interactions that are characterised by expressions of fairness and adherence to unbiased procedures.

Public order policing

Includes disorder, nuisance, protest, riots, and hooliganism.

Public surveillance technologies

Includes CCTV, Surveillance cameras, dash cams, and other surveillance technology.

Public/citizen mental health response

Responses to individual mental health needs and events and emergencies, e.g., mental health co-responder interventions.

Pulling levers / focused deterrence

Police engage a range of “levers” to incentivise target groups (high-risk offenders) to refrain from crime, or disincentivise crime activities.

Restorative justice

A specific technique in which victim reparations are centred in the management of crime events.

Road policing

Includes Random Breath Testing (RBTs), speed limit enforcement, etc.

School resource officers / school-based police officers

Police officers placed within schools to provide protection and enforcement.

Search and seizure

Police searches of citizens’ person or property, which may result in the confiscation (‘seizure’) of illegal items.

Specialised policing unit

For example, SWAT.

Sting operations

Can include drug market interventions, street-level drug law enforcement.

Police stops

Police performing street-level stops of individuals, which may entail stopping, questioning and patting down (‘frisking’) citizens. Includes pedestrian stops, stop-and-frisk, and street-checks.

Third party policing

Police engage non-police partners to use their powers or legal levers to intervene in crime/disorder scenarios, vicariously reducing crime and disorder. Non-police partners may be regulators, businesses, schools, etc. An example is Operation Galley.


The intervention includes training of, or by, police.

Training delivery modes and pedagogical approaches

Considers the method/approach of learning and development activities.

Other eligible interventions have included:

  • Facial recognition technology
  • Multi-Agency partnerships
  • Police contact
  • Police performance management, mentoring or appraisals
  • Public awareness campaigns
  • Warrants
  • Wildlife (anti-poaching, conservation).
Investigation scene
Police officer
Data Security


Which research designs are included in the GPD?

The GPD repository of eligible studies includes systematic reviews (with or without meta-analysis), randomized controlled trials (RCTs) and a wide range of quasi-experimental designs. We include cross-over designs, cost-benefit analyses, regression discontinuity designs, designs using multivariate controls (e.g., multiple regression), matched control group designs with or without pre-intervention baseline measures (propensity or statistically matched), unmatched control group designs with pre-post intervention measures which allow for difference-in-difference analysis, unmatched control group designs without pre-intervention measures where the control group has face validity, short interrupted time-series designs with control group (less than 25 pre- and 25 post-intervention observations), long interrupted time-series designs with or without a control group (≥25 pre- and post-intervention observations, raw unadjusted correlational designs where the variation in the level of the intervention is compared to the variation in the level of the outcome.

Why does the GPD exclude qualitative research?

We recognize the important contributions of qualitative research providing insights into all aspects of police and policing. Yet qualitative research does not answer the question of how a police or policing intervention impacts a stated outcome. The focus of the GPD is to offer police policy makers and practitioners access to study information that answers the question of intervention impact.

What is a GPD eligible study?

A GPD eligible study must:

  • be published after 1950, AND
  • be about a policing intervention, AND
  • report on a quantitative impact evaluation.