Lessons from reviewing and synthesising evidence on crime reduction
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Evidence syntheses are a common starting point when surveying the literature in many fields - they summarise and synthesise research findings across existing primary studies. The UK College of Policing, supported by the ESRC, took this approach when commissioning a team of academics to carry out research intended to support the newly established What Works Centre for Crime Reduction. The first task was to identify all systematic reviews in the published literature on crime reduction (work package 1). We were then required to carry out 12 further systematic reviews on topics agreed with the CoP and ESRC (work package 2). This presentation described what we learned from these two work packages. It will also briefly introduce EMMIE, a framework for communicating what works to practitioners wishing to implement an initiative in their area. Our overall impression is that the current (primary study) evidence base in crime reduction is not yet at a state of maturity that enables practitioners to judge whether an initiative would work for their local problem; this compromises how informative evidence syntheses can be. Our conclusion is that more efforts need to be devoted to testing and refining programme theories, since these can contribute to knowledge on generalisability and, therefore, suggest which initiatives are likely to bring about crime reduction effects across a range of settings.
![Lessons from reviewing and synthesising
evidence on crime reduction
What Works in Crime Reduction Conference
January 23rd 2017, British Library
Dr Lisa Tompson
l.tompson@ucl.ac.uk
UCL DEPARTMENT OF SECURITY AND CRIME SCIENCE
Lessons from reviewing and synthesising
evidence on crime reduction
[ ramblings in a post-EMMIE, post-truth world ]](https://image.slidesharecdn.com/wwendofprojectconftompson-170130142755/85/Lessons-from-reviewing-and-synthesising-evidence-on-crime-reduction-1-320.jpg)
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Lessons from reviewing and synthesising evidence on crime reduction
- 1. Lessons from reviewing and synthesising evidence on crime reduction What Works in Crime Reduction Conference January 23rd 2017, British Library Dr Lisa Tompson l.tompson@ucl.ac.uk UCL DEPARTMENT OF SECURITY AND CRIME SCIENCE Lessons from reviewing and synthesising evidence on crime reduction [ ramblings in a post-EMMIE, post-truth world ]
- 2. Overview • The evidence landscape ground zero • Assembling the ‘gold standard’ of the evidence base • The ‘EMMIE-ability’ of the current crime reduction evidence base – At systematic review level – At primary study level
- 4. (So-called) evidence hierarchies RCTs Quasi- experimental design Controlled observational studies Observational studies (no control group) Expert opinion Systematic reviews and meta-analysis
- 5. Systematic reviews • “a review of research literature using systematic and explicit, accountable methods” (Gough, Oliver and Thomas, 2012:2) • Find, sort, sift and synthesise • Supposedly overcome the limitations of individual studies and assess the evidence base as a whole
- 6. Searching for SRs - inclusion criteria • Systematic review or meta-analysis • Measured outcome of crime prevention/ crime reduction • Focused on a single intervention ~17,000 studies 838 studies 337 studies 82 studies
- 7. Sample (82 SRs of single interventions)
- 8. EMMIE • Effect – Effect direction and size • Mechanism – Mechanism/s activated (why it worked) • Moderator – Moderators/contexts that activate the mechanism/s • Implementation – Implementation conditions that support or obstruct delivery • Economic – Economic assessment of the cost effectiveness or cost-benefit ratio of what is delivered
- 14. What have we learnt? • Appraising quality is subjective automated Q-scoring helps to standardise • Most reviews don’t use the language of EMMIE – Different fields have very different reporting conventions • The evidence is generally weak on effect, and often on other dimensions, BUT: – Reviews can be strong on (say) moderators or implementation, even if effect is weak – We need to remember that reviews rely on primary study evidence
- 15. The misnomer of the ‘single intervention’ • Any intervention applied to people in the real world is fraught with complexity and variation After-school programmes to prevent delinquency Effect
- 16. The misnomer of the ‘single intervention’ • Any intervention applied to people in the real world is fraught with complexity and variation After-school programmes to prevent delinquency Effect
- 18. The misnomer of the ‘single intervention’ After-school programmes to prevent delinquency Effect After-school programmes to prevent delinquency After-school programmes to prevent delinquency
- 19. What’s in primary studies for EMMIE? • To date we have done systematic reviews on:
- 20. Effect Size (EMMIE) • Randomised control trials are scarce in crime prevention – None in anti-theft tag literature • Threats to bias are common Study Selection bias Measurement bias Regression to the mean Contamination effects Farrington et al. 1993 Medium Low Medium Medium Bamfield, 1994 High Medium Unclear Medium DiLonardo and Clarke, 1996 Medium Medium Unclear Medium Hayes and Blackwood, 2006 Medium Low Low Medium Beck and Palmer, 2011 Medium Medium Medium Medium Retailer A 2015 Medium High High Unclear Retailer B 2015 High High High Unclear
- 21. Mechanism-related information in the studies 19% Yes, alluded to 48% Not mentioned • 25 studies mentioned tag- related mechanisms • We spoke to retailers and loss prevention managers to corroborate the literature
- 22. Mechanism > Effect Increase the effort Increase the risks Reduce the rewards Reduce provocation Remove excuses 1. Target harden 6. Extend guardianship 11. Conceal targets 16. Reduce frustrations and stress 21. Set rules 2. Control access to facilities 7. Assist natural surveillance 12. Remove targets 17. Avoid disputes 22. Post instructions 3. Screen exits 8. Reduce anonymity 13. Identify property 18. Reduce emotional arousal 23. Alert conscience 4. Deflect offenders 9. Utilize place managers 14. Disrupt markets 19. Neutralise peer pressure 24. Assist compliance 5. Control tools/weapons 10. Strengthen formal surveillance 15. Deny benefits 20. Discourage imitation 25. Control drugs and alcohol
- 23. Mechanism > Effect Increase the effort Increase the risks Reduce the rewards Reduce provocation Remove excuses 1. Target harden 6. Extend guardianship 11. Conceal targets 16. Reduce frustrations and stress 21. Set rules 2. Control access to facilities 7. Assist natural surveillance 12. Remove targets 17. Avoid disputes 22. Post instructions 3. Screen exits 8. Reduce anonymity 13. Identify property 18. Reduce emotional arousal 23. Alert conscience 4. Deflect offenders 9. Utilize place managers 14. Disrupt markets 19. Neutralise peer pressure 24. Assist compliance 5. Control tools/weapons 10. Strengthen formal surveillance 15. Deny benefits 20. Discourage imitation 25. Control drugs and alcohol
- 24. Contextual variations that Moderate the effect • Type of tag – Hard vs. soft vs. ink tags – Overt (with or without warning message) vs. discreet • Type of shop – Layout – Staff availability and willingness to intervene – Other security: signs, guards, CCTV • Tagging strategy – Product lines – Dosage – Source-tagged vs. tagged in store
- 25. Implementation > Mechanism > Effect Increase the effort Increase the risks Reduce the rewards Reduce provocation Remove excuses 1. Target harden 6. Extend guardianship 11. Conceal targets 16. Reduce frustrations and stress 21. Set rules 2. Control access to facilities 7. Assist natural surveillance 12. Remove targets 17. Avoid disputes 22. Post instructions 3. Screen exits 8. Reduce anonymity 13. Identify property 18. Reduce emotional arousal 23. Alert conscience 4. Deflect offenders 9. Utilize place managers 14. Disrupt markets 19. Neutralise peer pressure 24. Assist compliance 5. Control tools/weapons 10. Strengthen formal surveillance 15. Deny benefits 20. Discourage imitation 25. Control drugs and alcohol
- 26. Conclusions • Extracting information that speaks to EMMIE is a murky business • Synthesising EMMIE data requires in-depth understanding – Of crime prevention theory – Of evaluation theory • Systematic review evidence depends on primary studies, so it is crucial that we raise awareness of EMMIE • Qualitative research is crucial for understanding the unique qualities of interventions – we ignore their value at our peril
- 27. Thank you Aiden Sidebottom, Amy Thornton, Lisa Tompson, Jyoti Belur, Nick Tilley, Kate Bowers and Shane D. Johnson University College London l.tompson@ucl.ac.uk UCL DEPARTMENT OF SECURITY AND CRIME SCIENCE