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This presentation discusses the analysis of repeat victims of Anti-Social Behaviour (ASB) based on 358,682 calls made to the West-Midlands Police over a 2-year period. Key questions addressed include the number of ASB repeat callers, concentration of ASB reporting, and the relationship between caller frequency and serious harm prediction. The implications for policing strategies and prevention efforts are also highlighted.
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3rd International NPIA-Cambridge Conference on Evidence-Based Policing July 2010 Repeat Victims of ASB: 358,682 Calls Barak Ariel, PhD Jerry Lee Centre of Experimental Criminology Institute of Criminology, UK
Diagnosing In-House Data Initial Questions For Analysing Outcomes How many ASB repeat callers? How many ASB calls? How much ASB concentration by caller? Questions Not Reached Yet How many callers = victims of 3rd parties? How many are individuals vs. corporate? Does frequency predict serious harm?
358,682 ASB Calls to West-Midlands Police 2-year Period 01/01/2008 – 31/12/2009 Calls vs. Callers: like crimes and victims Calls with Known Callers = 306,632 (85%) Calls with Unknown Callers = 52,050 (15%) Unique Callers = 196,278 (100%)
Conclusions ASB CALLS DO NOT VARY MUCH BY ASB Calls DO Vary by • Year • Month • Day of Week • Home Office Classifications • Time of Day • Type of Caller • Caller Frequency • Caller Repetition Over a Long Time
Year-to-Year Comparison 2008 • Total calls = 153,243 • Total callers = 105,842 • Percent Not calling in 2009 = 83% (drop-outs) 2009 • Total calls = 153,389 • Total callers = 107,701 • Percent who called in 2008 = 16% (persisting)
Initial Classification of 358,682 ASB Calls * motorway, bomb call, non-incident, highway agency
Type of Callers (Reading the Call Summaries) Very Different Picture: External Household Mental Stability, Substance Abuse Different Strategies for Different Callers?
Repeat ASB Callers Key Question: Concentration How Much ASB reporting comes from a small fraction of all callers to police about ASB? 21% of Callers 50% of Calls (over 2-year period)
Conditional Probability Conditional on How Many Calls In Past What are the odds of another ASB call in the future? The more prior calls, the greater the odds of a future call
Concerns With This Analysis: Right-Hand “Censoring”? (2 years only) Left-Hand “Censoring”? (From 1st call) Unequal exposure times from first call to end of 2-year period Unequal time period for prior call count
A New Method for Analysing Repeat Victimisation: Unique Phone Numbers with Equal Time PeriodsBEFORE & AFTER
Two-Way Data Censoring: Each Tel No. One Year Before & After 1/1/08 31/12/08 31/12/09
“Given 1 prior ASB call in 2008, what is the chance for one or more calls in 2009” • “Given 2 prior ASB calls in 2008, what is the chance for one or more calls in 2009 • “Given 3 prior ASB calls in 2008, what is the chance for one or more calls in 2009 And so on...
Research Design Issues Enough cases for Statistical Power (Discerning Police Effect) Not too Many Cases for Integrity of Treatment (Consistent Tactics)
Police Implications concentrate effort on high-frequency callers (Focus on Victims) What about places? Neighbourhoods? Concentrate on individuals--greatest risk? Emphasis on prevention and reassurance? How Can It Be Done?
3rd International NPIA-Cambridge Conference on Evidence-Based Policing July 2010 Policing Anti-Social Behaviour Repeat Victims of ASB: 358,682 Calls THANK YOU Barak Ariel, PhD Jerry Lee Centre of Experimental Criminology Institute of Criminology, UK