Introductory Guide to Crime Analysis and Mapping

INTRODUCTORY GUIDE TO CRIME ANALYSIS AND MAPPING

Introductory Guide to Crime Analysis and Mapping

Written by: Rachel Boba, Ph.D. Director, Crime Mapping Laboratory Police Foundation

November 2001 Report to the Office of Community Oriented Policing Services Cooperative Agreement #97-CK-WXK-004

The opinions, findings, and conclusions or recommendations expressed in this document are those of the authors and do not necessarily represent the official position or policies of the U.S. Department of Justice.

Acknowledgements

Acknowledgements

The author would like to thank Kristin Quayle for transcribing our training session during her summer here at the Police Foundation, as well as Mary Velasco and Erin Lane, Research Associates at the Police Foundation, for their careful review and comments.

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Table of Contents

Page

I. Introduction............................................................. 8

II. Introduction to Crime Analysis ............................. 9

Definition of Crime Analysis................................................................... 9

Types of Crime Analysis ....................................................................... 11 Intelligence Analysis .................................................................. 11 Criminal Investigative Analysis ................................................. 12 Tactical Crime Analysis.............................................................. 13 Strategic Crime Analysis............................................................ 13 Administrative Crime Analysis .................................................. 14

Crime Analysis Model ........................................................................... 15

III. Introduction to Crime Mapping .......................... 17

Historical Overview ............................................................................... 17

Types of Mapping .................................................................................. 18 Manual Pin Mapping ................................................................... 18 Computer Mapping ..................................................................... 19 Geographic Information System (GIS) ...................................... 19 Crime Analysis Mapping ............................................................ 20 GIS Components......................................................................... 20 Data representation............................................................ 20 Point feature ............................................................ 20 Line feature ............................................................. 21 Polygon feature ....................................................... 21 Image feature .......................................................... 22 Data of geographic features ............................................... 23 Point data ................................................................ 23 Line data.................................................................. 24 Polygon data ........................................................... 24

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Page

GIS toolbox ........................................................................ 25 Connectivity............................................................. 25 Contiguity ................................................................ 26 Geometry................................................................. 26

Visual display/mapping ...................................................... 27 Thematic approach.................................................. 27 Scale ....................................................................... 28

Querying GIS data ............................................................. 31 Tabular queries ....................................................... 31 Spatial queries......................................................... 32

IV. Introduction to Problem Solving ....................... 34

Definition of Problem Solving .............................................................. 34

SARA Approach to Problem Solving ................................................... 34 Scanning...................................................................................... 34 Analysis ....................................................................................... 34 Response..................................................................................... 35 Assessment................................................................................. 35

Crime Analysis and Problem Solving .................................................. 36

V. Data and Geocoding ............................................ 37

Types of Data ......................................................................................... 37 Tabular Data ................................................................................ 37 Geographic Data ......................................................................... 37

General Data Integrity Issues ............................................................... 38 Data Entry.................................................................................... 38 Timeliness ................................................................................... 38 Data Validity ................................................................................ 38 Reliability..................................................................................... 39 Data Transfer Process................................................................ 39 Data Confidentiality/Privacy ...................................................... 39

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Page

Data Management.................................................................................. 40 Metadata ...................................................................................... 40 Geocoding ................................................................................... 40 Introduction ........................................................................ 40 The geocoding process...................................................... 41 Step 1: Prepare the geographic and tabular files for geocoding............................. 41 Step 2: Specify geocoding parameters................... 45 Step 3: Geocode ..................................................... 46 Step 4: Review results............................................. 48 Step 5: If necessary, respecify parameters and geocode again. ...................................... 50 Conclusion ......................................................................... 51

VI. Spatial Analysis Techniques.............................. 52

Single Symbol Mapping ........................................................................ 52

Graduated Mapping............................................................................... 55 Graduation By Size ..................................................................... 55 Graduation By Color................................................................... 57 Classification Methods............................................................... 59 Natural breaks.................................................................... 59 Quantile.............................................................................. 60 Equal area.......................................................................... 61 Equal interval ..................................................................... 62 Standard deviation ............................................................. 63 Custom............................................................................... 65

VII. Crime Analysis Product Format and Dissemination............................................ 67

Factors to Consider............................................................................... 67

Methods of Dissemination .................................................................... 67

Components of Crime Analysis Products ........................................... 68

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Types of Crime Analysis Products ...................................................... 68 General Crime Analysis Product Elements ......................................... 70 Map Design Elements............................................................................ 71 Evaluating the Utility of Crime Analysis and Mapping Products ...... 73

VIII. References ......................................................... 74

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Introduction

I. Introduction

The following guide was developed from the curriculum for the "Introduction to Crime Analysis Mapping and Problem Solving" training course conducted by members of the Police Foundation's Crime Mapping Laboratory in 2001 and funded by the Office of Community Oriented Policing Services (COPS). The purpose of this document is to convert the information presented in the training into a succinct and readable report that makes it available to a larger audience than was reached through the training sessions. It is not intended to be a comprehensive document on crime analysis, crime mapping, and problem solving, but rather a "starter" guidebook for someone just entering the field or a reference manual for current crime analysts or other law enforcement analysts. The format of the document follows the format of the training slides loosely, but it is not necessary to read them together. This document stands on its own. For further reading on crime analysis and mapping, see other relevant documents written by the Police Foundation at or cops..

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