Crime Analysis for Problem Solvers

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Crime Analysis for Problem Solvers

• Problem Oriented Policing Conference
• Charlotte, NC
• October 2004

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1 How should crime data be used?
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Crime is relative
2003 Data
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Target 4 Walmart
Auto Theft
Vehicle Burglary
Total Vehicles Stolen 30 Recovered 50 Avg.
Time at Lot 109 min. Avg. Vehicle Year 1988
Top Makes/Models Toyotas Nissans
Walmart had 18 incidents predominantly between
1200 2000. The top makes include Fords and
Hondas. Most Common Lot Addresses within
Target Area 4 Walmart 75 N. Broadway Best Buy
59 N. Broadway
Auto Theft Time of Day
Auto Theft Day of Week
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Motor vehicle theft trend
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Types of motor vehicle theft
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Recovered vehicles
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Recovery by vehicle type
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2 Make better use of Calls-for-Service data
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Top 10 Calls for ServiceChula Vista 2003

• False Burglary Alarm 8,882 12
• Disturbance by Person 3,977 5
• Domestic Violence 3,692 5
• Traffic Collision 3,680 5
• Noise Disturbance 2,759 4
• 911 Hang Up 2,397 3
• Vehicle Theft 2,327 3
• Petty Theft 2,091 3
• Vandalism 1,983 3
• Suspicious Person 1,806 2
• Total 33,594 44

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Domestic Disturbance Calls
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3 What amount of data should be used?
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Too Much Data
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Miami
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(No Transcript)
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Too Little Data

• Use at least 15-20 per category.

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Drug-related calls
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Adding data
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4 What type of data are most appropriate?
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(No Transcript)
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Estimating Magnitude of the Problem

• Complaints to police 31
• Arrests 201
• Suspects 148
• Chronic offenders 60

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Estimating Offenses

• Chronic offenders 60
• Tricks per day 3 5
• Days per week 5
• Weeks per year 50
• Estimated transactions 67,500
• Clearance rate 3/10

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5 How else can In-house data be used?
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Utilize Narratives

• To determine usefulness of data
• To understand context of a problem
• Content analysis and coding for additional
  statistical analysis

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Example Construction Site BurglaryDifficulty
Index (Four Characteristics)
Skill Transport Access Time
0 No skill Walk away Outside/visible/unattached 0 to 5 minutes
1 Heavy, awkward, forcibly removed Car, small truck Outside attached, inside visible attached and/or unattached 5 to 10 minutes
2 Skills/tools Truck and/or trailer Secured inside More than 10 minutes
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Difficulty Index Initial Analysis
Difficulty Index Difficulty Index
Value Percent
0 2
1 4
2 11
3 11
4 16
5 28
6 13
7 8
8 7
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Port St. Lucie, FL Construction Site Burglary
Analysis N155
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Difficulty Index Preliminary Analysis
Skill Transport
Percent Percent
No skill 12 Walk away 12
Heavy/awkward/ forcibly removed 37 Small truck/car 70
Skills/tools 51 Large truck 17

Access Time
Percent Percent
Outside/visible/unattached 21 0 to 5 minutes 35
Outside attached, inside visible attached and/or unattached 41 5 to 10 minutes 37
Secured inside 38 More than 10 minutes 28


Port St. Lucie, FL Construction Site Burglary
Analysis N155-158
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6 When In-House Data Isnt Enough
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Auto Theft Offender Interviews
A number admitted taking stolen cars into Mexico for sale A number mentioned the ease of breaking into older Toyotas (as well as Hondas) A number said they can use any old Toyota key to unlock some of the Toyotas (didnt even need to shave the key) Many admitted to stealing from parking lots because it offered so many choices in unguarded settings
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Access Control A Critical Parking Lot Feature
Number of Auto Thefts

• Las Americas Safer than CV Mall in Other Ways
• -69 burglary
• -60 fights/disturb.
• -38 grand theft
• -84 petty theft
• zero robberies (16 at Chula Vista Mall)

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Traffic Congestion Problem Who Drives
to School and Why?
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Observations of Drop-Off/Pick-up Times Explain
Afternoon Crunch
School end time 300
School start time 830
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7 What Analysis is Most Useful to Police
Managers?
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Volume Outliers 10 Worst Parking Lots Account
for 15 of all Auto Thefts in City
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Rate Outliers Vehicle Theft Rate Per Spot vs.
Top 10 Lots
Median 3.1
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8 How can I use mapping to understand a problem?
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Mapping

• Use mapping sparingly
• Should not be the central method used to direct
  police efforts
• Mapping most useful for bringing data together,
  scanning, and presenting analysis results.

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Should we deploy officers based on this map?
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• Example Scanning

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• Example Bring Data Together

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Example Presentation of Results San Diego County
Recovery Rates
2001 Recovery Rates - Trucks
2001 Recovery Rates - Cars
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Example Presentation of Results
HIGHWAY closed section
CAB STAND
P
P
NEW CAB STAND
Tønsberg downtown area
P
P
Moved barristers
P
P
MOVED BUS STAND
TØNSBERG BRIDGE
Pparking lot no admission

• From Gypsy Cabs in Tønsberg a Case for
  Problem-Oriented Policing
• Johannes Knutsson, National Police Academy and
  Knut-Erik Søvik, Vestfold Police District

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9 How do I know theres a difference?
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Test Relationships

• Ad hoc reasoning
• Use of statistics
• Statistical vs. practical significance

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Date Span
Mean SD N
Residential Burglaries 4.36 23.66 614
Construction Site Burgs 2.52 4.16 225
Port St. Lucie, FL Construction Site Burglary
Analysis
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Time Span
Mean SD N
Residential Burglaries 7.31 8.47 479
Construction Site Burgs 14.64 7.79 130
Statistically significant at the .01 level
58 of the CSBTs has a date span of 0 or 1
Port St. Lucie, FL Construction Site Burglary
Analysis N155-158
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10 Did it work?
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Effort to Reduce Traffic Collisions Through
Citations
Results -Very weak correlation between cites
and collisions -Not statistically significant
Chula Vista Police Department
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Domestic Violence Intervention
Intervention Began
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Domestic Violence Intervention
Total of DV Incidents Total of Repeat Incidents Repeat Rate
1995 (pre-) 1,713 594 35
1999 (post) 1,527 525 34
of people revictimized 1 time 2 times 3 times 4 times 5 times
1995 (pre-) 65 19 10 3 3
1999 (post) 65 17 8 2 6
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Anti-Theft Device Passive Immobilizers in
Honda Accords
Year Immobilizers Introduced Into Accords
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Discussion and Questions

• Contact Information
• Deborah Weisel
• dlweisel_at_social.chass.ncsu.edu
• Karin Schmerler
• kschmerler_at_chulavistapd.org
• Rachel Boba
• rboba_at_fau.edu