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Crime Analysis for Problem Solvers Problem Oriented Policing Conference Charlotte, NC October 2004 #1 How should crime data be used? Crime is relative 2003 Data Target 4 Walmart Auto Theft Vehicle Burglary Total Vehicles Stolen: 30 % Recovered: 50% Avg. Time at Lot: 109 min.
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Crime Analysis for Problem Solvers Problem Oriented Policing Conference Charlotte, NC October 2004
Crime is relative 2003 Data
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 12:00 – 20:00. 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
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%
Too Little Data Use at least 15-20 per category.
Estimating Magnitude of the Problem • Complaints to police 31 • Arrests 201 • Suspects 148 • Chronic offenders 60
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 %
Utilize Narratives • To determine usefulness of data • To understand context of a problem • Content analysis and coding for additional statistical analysis
Example: Construction Site BurglaryDifficulty Index (Four Characteristics)
Difficulty Index: Initial Analysis 72% Port St. Lucie, FL Construction Site Burglary Analysis: N=155
Difficulty Index: Preliminary Analysis Port St. Lucie, FL Construction Site Burglary Analysis: N=155-158
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)
Traffic Congestion Problem: Who Drives to School and Why? AM Drivers and Walkers Paseo Bus Stops = All grades = K/1st Park
Observations of Drop-Off/Pick-up Times Explain Afternoon Crunch School end time: 3:00 School start time: 8:30
Volume Outliers: 10 Worst Parking Lots Account for 15% of all Auto Thefts in City
Rate Outliers: Vehicle Theft Rate Per Spot vs. Top 10 Lots Median: 3.1
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.
Example: Presentation of Results San Diego County Recovery Rates 2001 Recovery Rates - Cars 2001 Recovery Rates - Trucks
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 P=parking 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
Test Relationships • Ad hoc reasoning • Use of statistics • Statistical vs. practical significance
Date Span Port St. Lucie, FL Construction Site Burglary Analysis
Time Span *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: N=155-158
Effort to Reduce Traffic Collisions Through Citations Results: -Very weak correlation between cites and collisions -Not statistically significant Chula Vista Police Department
Domestic Violence Intervention Intervention Began