Crime Displacement and Diffusion Analysis
Also known as: Crime Displacement Analysis, Diffusion of Benefits Analysis, Weighted Displacement Quotient, WDQ Analysis
Displacement and diffusion analysis evaluates what happens around a crime-prevention intervention: does crime simply move to nearby areas, times, or targets (displacement), or do the benefits spill over so that crime also falls in surrounding untreated areas (diffusion of benefits)? Bowers and Johnson's weighted displacement quotient (WDQ) provides a simple, widely used metric that compares pre/post crime change in a target area, a surrounding buffer, and a control area.
Key highlights
- Directly addresses the central policy objection to crime prevention — that it just moves crime around — with a concrete, testable design.
- The weighted displacement quotient is a simple, transparent, easily computed metric that summarizes spillover relative to the direct effect.
- The three-zone design controls for background crime trends through the control area, sharpening causal interpretation.
- Captures the often-overlooked phenomenon of diffusion of benefits, correcting the assumption that displacement is inevitable.
- Generalizes across many situational interventions and crime types, enabling cumulative review and meta-analysis.
Intuition
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How it works
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When to use it
Use displacement and diffusion analysis when evaluating a place-based or situational crime-prevention intervention and you need to know whether crime reductions are real or merely relocated, and whether benefits extend beyond the treated area. It is appropriate when you can define a credible target, buffer, and control geography and obtain comparable pre/post crime counts for each. It is less suitable when the intervention is diffuse or citywide (no meaningful untreated buffer exists), when displacement could occur along non-spatial dimensions the design ignores (target, tactical, temporal, or offense displacement), or when crime counts are too small for stable ratios. The WDQ is descriptive and does not, by itself, provide a significance test.
Strengths & limitations
- Directly addresses the central policy objection to crime prevention — that it just moves crime around — with a concrete, testable design.
- The weighted displacement quotient is a simple, transparent, easily computed metric that summarizes spillover relative to the direct effect.
- The three-zone design controls for background crime trends through the control area, sharpening causal interpretation.
- Captures the often-overlooked phenomenon of diffusion of benefits, correcting the assumption that displacement is inevitable.
- Generalizes across many situational interventions and crime types, enabling cumulative review and meta-analysis.
- The WDQ is a descriptive ratio without a built-in statistical significance test or confidence interval, so sampling uncertainty is easy to ignore.
- Results are sensitive to how the target, buffer, and control boundaries are drawn, and there is no single correct buffer width.
- It addresses primarily spatial displacement and benefit, while displacement can also be temporal, tactical, target, or offense-based.
- Small crime counts in any zone make the ratio unstable and can produce extreme or undefined values.
- A poorly chosen control that is itself affected by the intervention biases the standardization and the conclusion.
Common pitfalls
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Applications
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Frequently asked
What is diffusion of benefits?
Diffusion of benefits is the spillover of crime reduction beyond the area or targets actually treated by an intervention. Because offenders often cannot perceive the precise limits of new prevention measures, they may overestimate the risk in a wider zone and reduce offending there too. It is the mirror image of displacement, and evaluations show it occurs at least as often, meaning prevention can yield a bonus rather than a leak of crime.
How do I interpret the weighted displacement quotient?
The WDQ expresses the change in the buffer area relative to the change in the target area, both standardized by a control. A positive value means crime fell in the buffer as well as the target — diffusion of benefits. A negative value means crime rose in the buffer as it fell in the target — displacement. A value near zero means the effect was contained in the target with little spillover. Larger magnitudes mean spillover was large relative to the direct effect.
Does crime prevention always just displace crime?
No. The belief that prevention inevitably relocates crime is contradicted by the evidence. Reviews such as Guerette and Bowers (2009) find that when displacement occurs it is usually partial — less than the gain in the treated area — and that diffusion of benefits is common. Offenders are not perfectly mobile or informed, opportunities differ across places, and reducing opportunity at attractive targets often lowers overall offending rather than simply moving it.
Sources
- 1.Bowers, K. J., & Johnson, S. D. (2003). Measuring the geographical displacement and diffusion of benefit effects of crime prevention activity. Journal of Quantitative Criminology, 19(3), 275–301.
- 2.Guerette, R. T., & Bowers, K. J. (2009). Assessing the extent of crime displacement and diffusion of benefits: A review of situational crime prevention evaluations. Criminology, 47(4), 1331–1368.
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Cite this page
ScholarGate. (2026, June 22). Crime Displacement and Diffusion Analysis. ScholarGate. https://scholargate.app/criminology/displacement-diffusion-analysis