Repeat Victims of ASB: 358,682 Calls

Barak Ariel, PhDBarak Ariel, PhD

Jerry Lee Centre of Experimental CriminologyInstitute of Criminology, UK

3rd International NPIA-Cambridge Conference on Evidence-Based Policing

July 2010

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?

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

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

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)

* motorway, bomb call, non-incident, highway agency

Very Different Picture:

External

Household

Mental Stability, Substance Abuse

Different Strategies for Different Callers?Different Strategies for Different 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)

CUMULATIVE Percentages of Callers and Calls(1/1/08 - 31/12/09)

How many calls/ callersCumulative

Percent of Callers Cumulative

Percent of CallsOnce or more 100% 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/ callersCumulative

Numbers of Callers Cumulative

Numbers of CallsOnce or more 196,278 306,632Twice or more 41,558 151,9123 times or more 17,999 104,7944 times or more 10,376 81,9255 times or more 6,986 68,3656 times or more 5,007 58,4707 times or more 3,816 51,3248 times or more 3,030 45,8229 times or more 2,442 41,11810 times or more 2,010 37,23011 times or more 1,681 33,940

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

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

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...

Raw Distributions: 2008 Predicting 2009

Frequency of Calls 2008

Callers with one or more call in 2009

among 2008 callersTotal 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)

TOTAL100% (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

Cumulative % Calls in 2009

from 2008 callersCalled 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%

Enough cases for

Statistical Power (Discerning Police Effect)

Not too Many Cases for

Integrity of Treatment (Consistent Tactics)

Top Callers: An Experimental

Sample?

nnumber of calls

in 2008number 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

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?

Policing Anti-Social Behaviour

Repeat Victims of ASB: 358,682 Calls

THANK YOU

Barak Ariel, PhDBarak Ariel, PhD

Jerry Lee Centre of Experimental CriminologyInstitute of Criminology, UK

3rd International NPIA-Cambridge Conference on Evidence-Based Policing

July 2010