About the Crime Reduction Toolkit and EMMIE


What is the Crime Reduction Toolkit?

The Crime Reduction Toolkit summarises the best available research evidence on what works to reduce crime. It uses the EMMIE framework described below to present evidence from systematic reviews of research on crime reduction interventions in a format that helps users to access and understand it quickly.


​The Crime Reduction Toolkit has been awarded a Best Practice certificate in the European and National Level category at the European Public Sector Awards 2017


What is a systematic review?

A systematic review summarises the research evidence from a number of studies on a particular topic and uses strict criteria to exclude studies that do not fit certain quality and methodological requirements. Some systematic reviews include meta-analyses which use statistical tests to estimate the overall effect of an intervention by combining data from multiple studies. Only interventions that have been subject to a systematic review have been included on the Crime Reduction Toolkit.   

What's in the toolkit and how can it help me?

The Toolkit lists crime reduction interventions which span a broad range of approaches and problems.  It is not an exhaustive list of interventions used to reduce crime as the Toolkit only contains those that have been subject to at least one systematic review.  The systematic reviews are interpreted, rated and presented using a framework termed EMMIE (see below).  We continue to add interventions to the Toolkit when new systematic reviews measuring crime reduction are published.

The Toolkit can be used by crime reduction practitioners and decision-makers to help them to understand what works well (and what doesn't work) according to the best available evidence.  It allows them to assess different interventions in terms of their impact on reducing crime and the strength of the evidence.  Toolkit users can also clearly see if there is any information on how and where interventions work best and whether the research includes any information on implementation and economic cost. Clicking on the intervention title provides a summary of the findings, any noteworthy issues relating to the intervention, and access to the references for further reading. 

What is EMMIE?

Evidence is presented using the framework EMMIE. EMMIE is a rating and ranking system which was developed by academics at University College London to help practitioners and decision-makers to access the evidence-base easily and quickly. EMMIE rates each intervention against the following five dimensions:

  • Effect

Impact on crime

Whether the evidence suggests the intervention led to an increase, decrease or had no impact on crime.

  • Mechanism

How it works

What is it about the intervention that could explain its effect?

  • Moderators

Where it works

In what circumstances and contexts is the intervention likely to work / not work?

  • Implementation

How to do it

What conditions should be considered when implementing an intervention locally?

  • Economic cost

How much it costs What direct or indirect costs are associated with the intervention and is there evidence of cost benefits?


Quick Start Guide to EMMIE

An introduction to EMMIE - the framework used to rate the best available evidence on crime reduction interventions - using Alley gating as an example.  To get started click on the Quick Start Guide below.


To find out more about EMMIE you can read the method statement

How do I interpret the impact of each intervention on crime reduction?

There are two steps to interpreting the impact of an intervention on crime.

    • The impact on crime effect scale shows you what the research evidence suggests about the effect of an intervention on reducing crime.  The scale ranges from interventions which show an overall decrease in crime ( ) to those  which show an overall increase () In some reviews, most studies showed an increase (or a decrease) in crime but a small number of studies within the review showed the opposite effect.  These are highlighted on the effect scale with a flag symbol ()
  • The quality scale (shaded bars beneath the effect scale symbols) shows you the quality of the research evidence. This ranges from no information (where we cannot comment on quality) to very good quality where we can feel confident in relying on the findings i.e. most forms of bias that could influence the study conclusions can be ruled out.


Further reading

"Introducing EMMIE: an evidence rating scale to encourage mixed-method crime prevention synthesis reviews"; JOHNSON, Shane D.; TILLEY, Nick; BOWERS, Kate; Journal of Experimental Criminology, 2015

The EMMIE framework was developed by UCL Jill Dando Institute as part of a programme of work designed to help build the toolkit co-funded by the College of Policing and the Economic and Social Research Council (ESRC). ESRC Grant title: 'University Consortium for Evidence-Based Crime Reduction'. Grant Ref: ES/L007223/1.