The Role of Theory in Evidence-Based Policing

September 10, 2018


by Joel M. Caplan, PhD

Associate Professor, Rutgers University School of Criminal Justice

Deputy Director, Rutgers Center on Public Security


Theory is to evidence-based policing (EBP) as water is to shoreline. They help define each other. Theories shape evidence-based practices, and newly tested practices help to advance theories. A spectrum of theories from criminology, ecology, psychology, geography, sociology and economics, are commonly used to craft research, experiments, and data analyses for police agencies; and policing initiatives are routinely helping to validate and advance theories. Theories are ‘translational’ in that they’re renderings of scientific discoveries synthesized into sets of expectations about phenomena that police can consider for policies or practices. According to psychologists Tversky and Kahneman, the job of decision makers is not always to be right, but to figure out the odds in any decision they have to make and play the odds well[1]. Theory guides these decisions.


A theory is a supposition or a set of ideas intended to explain something. Theories arise from repeated and independent testing of hypotheses, in different settings, over time, whereby sets of principles emerge when similar research findings appear. Theories are testable, and may be proven wrong. But a theory is distinct from a hypothesis. Theory is derived from numerous sources of evidence and academic study. A hypothesis is a proposed explanation made on the basis of limited evidence as a starting point for further investigation. In the realm of policing, if a theory is ‘clear and convincing evidence’, then a hypothesis is ‘reasonable suspicion’.


For EBP:

  • Theory safeguards against arbitrary decision-making.
  • Theory offers guidance about which variables to include or control for in analyses, and how to make results actionable.
  • Theory enhances accountability and helps share the burden of crime prevention among multiple agencies and stakeholders.
  • Theory adds context and meaning to data and helps to answer why and in what situations results matter.
  • Theory can guide the coordination of multiple intervention programs at once, and help to anticipate unwanted side effects.
  • Theory helps explain human behavior and, thus, crime events and patterns.
  • Theory guides innovative and creative solutions to problems.


Big data and sophisticated technologies do not guarantee easier or more certain decisions for police. With a growing reliance on fusion centers, real-time crime centers, and software to manage, analyze and communicate data, there’s a danger of thinking that numbers will speak for themselves[2]. The opposite is true. Theory plays a crucial role in decisions about what datasets or variables to include in statistical analyses, how they might interact, what could confound, mediate or moderate results, what the results mean, and so on[3]. Without a theoretical framework, analysts can be distracted from critical decisions they must make[4]. According to Wise and Shaffer[5] theory is a tool to safeguard against arbitrary decision-making “by providing a coherent and reasoned framework” from which to act. Theory enables actionable results.


Policing has witnessed the consequences of poorly woven analysis, theory, and responsive actions. Notable examples include activities performed at crime hot spots that are solely offender-focused and, thus, disconnected with the ecological theories and spatial analyses that informed the place-based deployments. Although hot spots policing is sometimes coupled with Broken Windows Theory, the operational practices often implemented for crime prevention (such as stop, question, frisk) are detached from the root spatial causes, attractors, or generators of illegal behaviors (e.g., the actual broken windows) and instead focus reactively on offenders (i.e., without fixing the actual broken windows). A result is that hot spots persist and appear resilient over time, despite the many foot patrols, arrests or citations utilized there. As was recently questioned in The New Yorker “What if vacant property received the attention that, for decades, has been showered on petty crime?” Police can use theory to engage non-police stakeholders and justify sharing the burden of crime prevention with coordinated activities at the most vulnerable places.


Police who ask ‘where’ should also ask ‘why’. Theory provides a framework for explaining results, and for elucidating why and in what contexts the results matter[6]. Theory can help police prescribe responses to existing crime problems or emerging threats, and also to understand the impacts that their presence at targeted areas will have on risk calculations of people located nearby. Routine Activities, Rational Choice and Deterrence theories might come to mind. But so could Crime Pattern Theory or the Theory of Risky Places because the police are integral features of the environmental backcloths they patrol. Their movements add to its spatial dynamics, with varying levels of guardianship and vulnerability throughout the jurisdiction at any given moment in time. In fact, frequent directed patrols at particular target areas may inadvertently become expected or predictable qualities of spaces that motivated offenders adapt to[7] [8] if theory is not used to inform matters of timing, frequency and saturation.


EBP needs ongoing, continued impact. It could prosper from theoretically informed adoptions of newly proven practices that are phased in and out at the right times to optimize their crime prevention benefits with sustained impacts. Theory can guide the coordination and complementarity of multiple intervention programs at once, and serve as a barometer for balancing variety, intensity and timing of crime prevention programing.


Crime is an outcome of behavior. Theories help explain human behavior. A meta-analysis[9] of 11 intervention programs reported that decreases in crime relate not only to the offender-centric strategies but also to steps taken to modify the environments in which they operate. This finding complements criminological and psychological theories that reveal how environments influence behavior[10]. For example, environmental psychology[11] suggests that situationally-induced emotions can provoke a criminal response among both rational or irrational people. If people commit illegal behavior enough in the same setting, the physical environment (itself) can shape the subsequent human behavior (even unconsciously)[12]. The Theory of Risky Places (TRP) offers a way of modeling crime-prone settings for situational crime prevention. It assists in recognizing patterns of crime attractors that appear in the landscape, accounting for spatial relationships of environmental features that change over time. Police departments such as in Atlantic City have operationalized TRP to activities aimed at disrupting key ‘crime risk narratives’ through planned changes to the environment, including strategically allocated vehicle, bicycle and foot patrols. Violent crimes decreased 36% and the benefits have been sustained for well over 18 months to-date[13].


EBP isn’t merely about ingesting published research. It’s more than just methods and results. It’s about police agencies challenging themselves to turn theories into practice and then measure outcomes. Theoretical frameworks inform thinking behind new or innovative trials, the decisions that are made during a tour of duty, and how translations of empirical research provide new directions for operational practices[14]. Marcia Finlayson[15] summarized it well: “Theory defines and sets parameters on the way we think, what we focus on, and how we interpret what we see.”


Theories offer a check on our assumptions or preconceived notions. They shape evidence-based practices, and vice-versa. Theories help to move policing forward.


[1] Lewis, M. (2016). The Undoing Project: A Friendship that Changed Our Minds. W. W. Norton & Company: NYC, p248

[2] Wise, A. F. and Shaffer, D. W. (2015). Why theory matters more than ever in the age of big data. Journal of Learning Analytics, 2(2), 5-13.

[3] Wise & Shaffer, 2015

[4] Wise & Shaffer, 2015; Leek, J. T., & Peng, R. D. (2015). Statistics: p values are just the tip of the iceberg. Nature, 520, 612.

[5]  Wise & Shaffer, 2015, p 6

[6] Wise & Shaffer, 2015

[7] See Chapter 4: Caplan, J.M. & Kennedy, L. W. (2016). Risk Terrain Modeling. Crime Predictions and isk Reduction. Oakland, CA: University of California Press.

[8] This may also be relevant for ‘patrols’ via CCTV cameras. See: Piza, E. L., Caplan, J. M., & Kennedy, L. W. (2017). CCTV as a Tool for Early Police Intervention: Preliminary Lessons from Nine Case Studies. Security Journal. 30, 247-265.

[9] Braga, Anthony A., and David Weisburd. 2010. Policing Problem Places: Crime Hot Spots and Effective Prevention. New York, NY: Oxford University Press.

[10] Louiselli, J. K., & Cameron, M. J. (Eds.). (1998). Antecedent control: Innovative approaches to behavioral support. Baltimore, MD: Brookes Publishing. –and– Kennedy, L. W. and Forde, D. R. (1998). When push comes to shove: A routine conflict approach to violence. Albany, NY: State University of New York Press.

[11] It is concerned with the effects of the natural and built environment on human behavior.

[12]  Spiegel, A. (2015, January 5). What heroin addiction tells us about changing bad habits. Retrieved from

[13] For the full report, see

[14] Finlayson, M. (2007). Why theory matters. Canadian Journal of Occupational Therapy, 74(4), 291-291.

[15] (Finlayson, 2007, p 291)

Membership Spotlight – Valarie Findlay, Research Fellow, Police Foundation (US)

Coexistence: Evidence-Based Policing and Emerging Technologies

Valarie Findlay – Research Fellow, Police Foundation (US)

Evidence-based policing promises to be a powerful force for change and holding significant value for police organizations, the public and community safety. Often misunderstood, evidenced-based policing promotes the importance of practices based on scientific evidence that demonstrates what works ‘best’.

Plainly stated (sort of), qualitative and quantitative data is gathered from operational practices in a controlled framework that accounts for fluid environmental factors. Later, this data is analysed to fact-based evidence used to improve policies and procedures.

What evidence-based policing is not is the uncontrolled, empirical collection of data or its arbitrary use to implement or change procedural approaches and practices. Properly constructed, it does the opposite.

Allowing the integration of other research methods, such as discourse analysis, can create context where dynamic factors influence responses, such as offender interactions that may differ depending on circumstance, individual, neighborhood or city.

A linkage between research and practice, evidence-based practices hinge on the value of anecdotal and formalised evidence from measurable policing functions – from implementing guidelines to crime prevention. This nexus of controlled theory married with practice outcomes is gaining traction as it allows for faster operationalisation of academic research. From this, the best quality evidence can be used to shape ‘best practices’ through a process of re-testing and measuring the hypothesis.

Looking at both static and dynamic factors, the ones that change analogue and expected outcomes, is valuable to policing since its a human-behaviour driven profession. It’s easy to presume that under a particular scenario that under “normal” circumstances any person would react a certain way or that from the officer’s “experience” a certain outcome is presumed; this is what evidence-based policing stands to clarify.

The field of medicine is a good example. It’s widely accepted by professionals that diagnostics rely on three important areas of ‘evidence’: clinical signs, pathology and anecdotal (patient-view) since how disease presents itself physically, biologically and practically varies by individual. These diagnostic axioms produce irrefutable facts that remain relevant despite the use of technology; noting, centuries ago diagnostics were largely anecdotal and treatment was empirical.

For policing, an evidenced-based approach could look like this: a hypothesis is drawn from anecdotal evidence showing community-based policing programs deter recruitment of youth in street-level gangs. A sample group or area is selected to test the hypothesis by collecting data from practice activities by the subject matter experts (officers). Controlled by research methods that isolate criteria (demographic, circumstantial, geographic, etc) findings can be re-tested with outcomes confirmed, creating procedural or programmatic approaches.

Turning to technologies and how they could assist in evidence-based approaches, I’ll preface this by saying identify the “problem” and organisational requirements and letting those drive the selection of the technology; opposite view of how technology can be used to address all problems only serves the vendors.

Using artificial intelligence (AI) as an example – a hot topic across all sectors – may solve one of policing’s longstanding problems with the persistence of analogue data alongside electronic data and converting it into usable intelligence. AI could play a key role in addressing this problem not necessarily as an approach that automates decisions, actions and responses, but aiding in them.

Clearly, the more integrated public safety data is, whether individually identifying or statistically informing of a group or area, the more informative it is. AI can create generative processes that correlate large amounts of data, replicating ‘human’ thinking through algorithms and digitized heuristics, learning from outcomes. These predictive, adaptive responses can then be extended to similar problems making AI inherently useful to some aspects of policing.

The value to evidenced-based practices could improve data analytics across many programs – crime prevention and interdiction, investigative functions in analysis and intelligence gathering, from tip consolidation to complex field intelligence.

Despite AI’s ability to rapidly correlate and create associations with data, as with any technology, it has limitations and risks. The outputs and conclusions generated by AI processes are only as good as the input data and algorithms – it is truly a matter of ‘garbage in, garbage out’ and AI will not magically improve the quality of input data.

While ethics and privacy issues arise with AI’s ambiguous processes, for evidenced-based policing to explore its value, high-integrity algorithm, validation and verification will be key to establishing trust and confidence for all sides.


About Valarie:

Valarie Findlay is an ASEBP Member and a research fellow for the Police Foundation (USA) with two decades of senior expertise in cyber security and policing initiatives. She has worked extensively on federal cyber initiatives and is a member of the Canadian Association of Chiefs of Police eCrimes Cyber Council, as well as other federal cyber councils in Canada and the US. She holds a Masters in Sociology and a Masters in Terrorism Studies from the University of St. Andrews; her dissertation, “The Impact of Terrorism on the Transformation of Law Enforcement” examined the transformation of law enforcement in Western Nations.