1. 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

2. Sherman, 1998

3. 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?

4. 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 = ,278 (100%)

5. 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

6. 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)

9. Initial Classification of 358,682 ASB Calls
* motorway, bomb call, non-incident, highway agency

12. Type of Callers (Reading the Call Summaries)
Very Different Picture:
External
Household
Mental Stability, Substance Abuse
Different Strategies for Different Callers?

13. 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)

14. 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%

15. 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

16. 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

18. 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

19. A New Method for Analysing Repeat Victimisation: Unique Phone Numbers with Equal Time Periods BEFORE & AFTER

20. 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/ /12/ /12/09

21. “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...

23. 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%)

24. 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%

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

26. 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

27. 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?

28. 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