Repeat Victims of ASB: 358,682 Calls 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

Sherman, 1998

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%)

ASB CALLS DO NOT VARY MUCH BY 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 21% of Callers  50% of Calls (over 2-year period) 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)

CUMULATIVE Percentages of Callers and Calls (1/1/08 - 31/12/09) How many calls/ callers Cumulative Percent of Callers Cumulative Percent of Calls Once or more 100% Twice or more 21.173% 49.542% 3 times or more 9.170% 34.176% 4 times or more 5.286% 26.718% 5 times or more 3.559% 22.295% 6 times or more 2.551% 19.068% 7 times or more 1.944% 16.738% 8 times or more 1.544% 14.944% 9 times or more 1.244% 13.410% 10 times or more 1.024% 12.142% 11 times or more 0.856% 11.069%

Cumulative NUMBERS of Callers and Calls (1/1/08 - 31/12/09) How many calls/ callers Cumulative Numbers of Callers Cumulative Numbers of Calls Once or more 196,278 306,632 Twice or more 41,558 151,912 3 times or more 17,999 104,794 4 times or more 10,376 81,925 5 times or more 6,986 68,365 6 times or more 5,007 58,470 7 times or more 3,816 51,324 8 times or more 3,030 45,822 9 times or more 2,442 41,118 10 times or more 2,010 37,230 11 times or more 1,681 33,940

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 Periods BEFORE & AFTER

Two-Way Data Censoring: Each Tel No. One Year Before & After Prior n of events within a fixed period (365 days) cut-off point: one day Conditional n of events, within a fixed period (365 days) 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...

TOTAL Called 11 Times or More 2.93% (506) 15.33% (6,592) Raw Distributions: 2008 Predicting 2009 Frequency of Calls 2008 Callers with one or more call in 2009 among 2008 callers Total Calls in 2009 from 2008 callers Called Exactly Once 56.02% (9,671) 35.72% (15,357) Called Exactly Twice 18.49% (3,193) 15.98% (6,870) Called Exactly 3 times 8.38% (1,447) 9.21% (3,959) Called Exactly 4 times 4.88% (843) 6.07% (2,611) Called Exactly 5 times 3.15% (544) 4.98% (2,143) Called Exactly 6 times 2.25% (389) 4.12% (1,772) Called Exactly 7 times 1.44% (248) 2.94% (1,266) Called Exactly 8 times 1.18% (204) 2.61% (1,123) Called Exactly 9 times 0.71%(123) 1.70% (733) Called Exactly 10 times 0.56% (97) 1.32% (569) Called 11 Times or More 2.93% (506) 15.33% (6,592) TOTAL 100% (17,265) (16.03%) 100% (42,995) (28.03%)

Conditional Probability: 2008 Predicting 2009 Priors in 2008 Cumulative % of Callers with one or more calls in 2009 among 2008 callers % Calls in 2009 from 2008 callers Called once or more 16.03% 28.03% Called twice or more 7.05% 18.02% Called 3 times or more 4.09% 13.54% Called 4 times or more 2.74% 10.96% Called 5 times or more 1.96% 9.26% Called 6 times or more 1.45% 7.86% Called 7 times or more 1.09% 6.70% Called 8 times or more 0.86% 5.88% Called 9 times or more 0.67% 5.15% Called 10 times or more 0.56% 4.67% Called 11 times or more 0.47% 4.30%

Research Design Issues Enough cases for Statistical Power (Discerning Police Effect) Not too Many Cases for Integrity of Treatment (Consistent Tactics)

An Experimental Sample? average number of calls in 2009 Top Callers: An Experimental Sample? n number of calls in 2008 number of calls in 2009 average number of calls in 2009 200 5,867 (3.8%) 3,811 (2.5%) 19.15 400 8,755 (5.7%) 5,259 (3.4%) 13.18 1,000 14,693 (9.6%) 8,322 (5.4%) 8.33 22,000 69,401 (62.9%) 28,108 (18.3%) 1.28

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?

Repeat Victims of ASB: 358,682 Calls THANK YOU 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