lecture slides designing an experiment

Reducing Crime Harm by 50%: Designing a Triple-T Experiment

in Evidence-Based Policing

Dr. Barak Ariel and ACC Neil Wain (ret)

Summary

• Recent Evidence on Hot Spots Policing

--Philadelphia—no GPS, no impact

--Manchester—no GPS info used

--Dallas AVL—Info used and impact

• Designing a TTPS Triple-T Experiment

• Station-Level Compstat

• Hot Spots of violence—GPS with Car, Foot?

• Near-Miss Repeat Burglaries

• Gun Seizures by Targeting Warrant Breaches

Recent Evidence on Hotspot Policing

2nd Philadelphia Hot Spots Experiment

2nd Philadelphia Hot Spots Experiment

• Focus on Violent Crime

• 81 Hot Spots

• Patrol Captains consulted – Foot Patrol – Problem Solving – Offender Targeting

• Small clusters (5 felonies/15 inc misdemeanor)

What did the officers do in Philadelphia?

• Wide operational variation!

– Foot patrol times – Problem Solving with community – Offender targeting

• Other Output Measures

– Pedestrian stops – Automobile stops – Narcotics crime

Results

• Offender Targeting – All violence -22% – Violent Felonies -31%

• Foot Patrol

– No effect

• Problem Solving

• No effect

• Displacement? Diffusion of Benefits?

Why did the foot patrol not work?

• Design

• Dosage

• More experienced Officers!

• Front Line supervision

• NOT TRACKED

GMP Operation Ulysses

Even when you track it, does it work?

OP Ulysses Area A3

Area “A3”Patrols

Type In Out Duration

Response 01/06/2011 21:42 01/06/2011 21:43 00:01:04

Response 01/06/2011 21:43 01/06/2011 21:44 00:00:57

Sergeant (NPT) 01/06/2011 21:32 01/06/2011 21:36 00:04:01

Sergeant (NPT) 01/06/2011 21:38 01/06/2011 21:40 00:01:55

Traffic 02/06/2011 00:36 02/06/2011 00:37 00:01:01

Inspector 01/06/2011 21:38 01/06/2011 21:40 00:02:02

Total Time 0:11:00

Start Date/time:

01/06/2011 19:00:00

End Date/time: 02/06/2011 02:00:00

Dallas AVL Experiment

Dallas AVL Experiment – A Success

• Use of GPS tracking

• Does it Increase patrol in beats/hotspots?

• Yes + No!

• Findings – Successful in hotpots

• Why? Tracking and COMPSTAT

Does COMPSTAT Work?

• The Dallas PD AVL Experiment

– Use of COMPSTAT

• Accurate and timely intelligence.

• Effective tactics

• Rapid deployment

• Relentless follow-up and assessment

– Management Information

The Trinidad and Tobago Experiment

Targets and Aims

• Reduce Serious Crime by 50% compared to control conditions

• Use all 3 “Triple Ts” of Evidence Based Policing

– Targeting the power few

– Testing the Intervention through rigorous science and

– Tracking with advanced technology and effective management

Selection of Targets

• Police Station Districts

• Of all possible geographic stations, select the top percentile that is responsible for most of crime and disorder in Trinidad and Tobago

• Focus heavily on violent crimes (woundings and homicide) and overall CHI

• Focus indirectly on all other serious street crime

• Increase legitimacy of TT police through effective but fair procedures

Proposed Program

• Station-Level Compstat Every 14 days • --heart and head, targeting predicted crime

• Hot Spot Patrols Hot Times—primarily in vehicles

• Patrol Tracking Maps for Compstat Discussion

• Near-Miss Repeat Burglary Interventions

• Warrant Breach Searches for Guns

• Roadblock Stop & Search

Process of Random Assignment

1. Rank-Order all TT Stations according to n of incidents in 12 months (shootings, homicides, woundings)

2. Exclude Besson Police Station--all treatment *

3. Exclude stations with fewer than 5 incidents

4. Pairwise Random assignment

creating 24 pairs ______

* Extreme outlier with 188 incidents; next in rank is Morvant Police Station with 49 incidents

0

1000

2000

3000

4000

5000

6000

7000

8000

Sum ofshootings+woundings+homicides

+attempted homicides

Sum of All Offences

N Incidents = 412 Mean per station

=17.2

N Incidents = 7,926

Mean per station = 330.3

N Incidents = 399 Mean per station

= 16.6

N Incidents = 7,759

Mean per station = 323.3

Total N Incidents in 12 months

Control

Treatment

Station A 49

Station B 42

Station C 40

Station D 40

Station E 38

Station F 37

Station G 36

Station H 35

Station I 26

Station J 26

0

10

20

30

40

50

60

C E C E E C C E E C

N s

ho

oti

ngs

, wo

un

din

gs, h

om

icid

es

in 1

2 m

on

ths

Random Assignment

Top 1-10 stations - RA Pairs

26 25

24

21

19 19 18 18

17 16

0

5

10

15

20

25

30

C E C E E C C E E C

N s

ho

oti

ngs

, wo

un

din

gs, h

om

icid

es

in 1

2 m

on

ths

Random Assignment

Top 11-20 Station – RA Pairs

16 16

14

13 13

12 12

11

9

8

0

2

4

6

8

10

12

14

16

18

C E C E E C C E E C

N s

ho

oti

ngs

, wo

un

din

gs, h

om

icid

es

in 1

2 m

on

ths

Random Assignment

Top 21-30 Stations - RA Pairs

0

1

2

3

4

5

6

7

8

9

C E C E C E C E C E E C C E C E C E

N s

ho

oti

ngs

, wo

un

din

gs, h

om

icid

es

in 1

2 m

on

ths

Random Assignment

Top 31-48 Stations - RA Pairs

Tracking Patrols

GPS Tracking

1. AVL GPS-based trackers

2. Crucial: It will help us measure the link between police presence and crime

For instance

area Longitude Latitude RA activity time activity time

10 -61.685643 10.155458 treatment entered 17:14:10 exited 17:28:14

11 -61.593408 10.690763 control entered 17:38:58 exited 17:57:51

12 -61.572013 10.716984 control entered 20:28:35 exited 20:29:15

13 -61.558364 10.691809 treatment entered 21:11:03 exited 21:13:01

14 -61.552897 10.186984 treatment entered 20:44:41 exited 20:48:37

15 -61.53434 10.686686 control entered 21:00:54 exited 21:01:35

16 -61.517857 10.655706 control entered 17:15:32 exited 17:16:08

17 -61.514725 10.712017 treatment entered 15:24:48 exited 15:34:19

18 -61.506472 10.651299 control entered 18:27:20 exited 18:27:59

19 -61.505651 10.657882 control entered 20:43:57 exited 20:44:51

20 -61.503992 10.650514 treatment entered 15:51:50 exited 16:25:55

Measuring Patrol Strategy

0 200 400 600 800

Tunapuna

Sangre Grande

Princes Town

Inter-Agency Task Force

Marabella

Belmont

St Clair

Freeport

Chaguanas

Arouca

Woodbrook

Arima

Morvant

Malabar

Besson Street

Central

Ste Madeline

La Horquetta

0 200 400 600 800

Fyzabad

Barataria

Mon Repos

Carenage

Oropouche

St James

Cunupia

Valencia

San Juan

Penal

Rio Claro

Guard Branch

La Brea

West End

Longdenville

Santa Cruz

Piarco

Moruga

Roxborough

Crown Point

The Available Evidence: Total Number of Patrols Per Day

0.00%

1.00%

2.00%

3.00%

4.00%

5.00%

6.00%

7.00%

8.00%0

0:0

0

01

:00

02

:00

03

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04

:00

05

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06

:00

07

:00

08

:00

09

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10

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11

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12

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13

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15

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16

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17

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18

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19

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20

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21

:00

22

:00

23

:00

Patrols - Time of Day

One Patrol Unit

60> minutes per day

30-59 minutes per day

<29 minutes per day

C++ Density Maps for Patrol Dosage

60> minutes per day

30-59 minutes per day

<29 minutes per day

Winning the Hearts and Minds of the Patrol Officers

Sacramento Hot spot RCT – Officer Survey

Q. What were your initial thoughts about the hot spot study?

Waste of time Will reduce pro-activity Will increase response times Responsible for too many tasks Displacement Won’t get to do what we want to do

Q. If you were in charge, where would you direct officer proactivity?

Let the officer decide where to patrol Officers know their beats; it should be based on their expertise Have a hot spot team Keep doing what we have been doing

Sacramento Hot spot RCT – Officer Survey

Q. Who would make you more open to a new idea in policing?

Sergeant – 23 Friend – 15 Chief – 12 Lieutenant – 11 FTO – 6 Captain – 5 Deputy Chief – 5

Sacramento Hot spot RCT – Officer Survey

Q. Who would make you more open to a new idea in policing?

Sergeant – 23 Friend – 15 Chief – 12 Lieutenant – 11 FTO – 6 Captain – 5 Deputy Chief – 5

Managing TT Police Patrol Time

– Communication

– Training

– Front Line Supervisors

– Organisational Support (Reward)

– Time

– Senior Officer visibility

– Accountability

_____

* Based upon Famega, Frank and Mazerolle (2007) Managing Police Patrol Time: The Role of Supervisor Directives.

But What Works In TTPS?

But What Works In TTPS?

• May have different patterns of influence

• It is all about social networks

• Just like the tipping point

• So find your opinion leaders in each station

A Social Network

Networks Work!

• Persuade your opinion leaders

• They can persuade others

• And working together, yes we can...

We can, Together, Reach a GOOD….

We can, Together, Reach a GOOD….

Tipping Point

Cambridge Criminology and…

Trinidad & Tobago Police Service

Dr. Barak Ariel and ACC Neil Wain (ret)

Thank You!