How to Collect and Analyze Data: A Manual for Sheriffs and Jail

220 Pages·2007·3.42 MB·English

U.S. Department of Justice
National Institute of Corrections
How to collect and analyze data:
a Manual for Sheriffs and Jail administrators
U.S. Department of Justice
National Institute of Corrections
320 First Street, NW
Washington, DC 20534
Morris L. Thigpen
Director
Thomas J. Beauclair
Deputy Director
Virginia Hutchinson
Chief, Jails Division
Vicci Persons
Project Manager
National Institute of Corrections
http://www.nicic.org
How to collect
and analyze data:
a Manual for
Sheriffs and Jail
administrators
3rd edition
Gail Elias
July 2007
NIC Accession Number 021826
This publication was funded by the National Institute of Corrections, U.S. Department of Justice. Points of view
or opinions stated in this publication are those of the author and do not necessarily represent the official position
or policies of the U.S. Department of Justice.
Copyright © 2007, Voorhis Associates, Inc. The National Institute of Corrections reserves the right to reproduce,
publish, translate, or otherwise use and to authorize others to publish and use all or any part of the copyrighted
material contained in this publication.
Ta b l e o f C o n t e n t s
FOREWORD........................................................vii
PREFACE........................................................... ix
ACKNOWLEDGMENTS .............................................. xi
CHAPTER 1: INTRODUCTION........................................ 1-1
The Situation..................................................... 1-3
Traditional Resources Have Failed To Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Resource 1: Introductory Statistics Courses........................... 1-4
Resource 2: Information Systems Seminars........................... 1-4
Resource 3: Research Methods..................................... 1-5
Additional Resources............................................... 1-5
CHAPTER 2: GOOD MANAGEMENT REQUIRES GOOD INFORMATION ... 2-1
What Is Management?.............................................. 2-3
Ways To Get the Facts.............................................. 2-4
What Can You Do With Data?........................................ 2-4
Example 1: Better Budgeting and Allocation of Funds .................. 2-4
Example 2: More Effective Deployment of Staff....................... 2-5
Conclusion....................................................... 2-6
CHAPTER 3: INFORMATION THAT SHOULD BE COLLECTED ............ 3-1
Writing Good Problem Statements.................................... 3-3
Identifying Data Elements From Problem Statements ..................... 3-4
A Catalog of Correctional Data Elements............................... 3-5
Inmate Population Data Elements................................... 3-6
Inmate Profile Data Elements...................................... 3-7
Operational Data Elements....................................... 3-10
Criminal Justice System Performance Data Elements .................. 3-12
A Word About Collecting Data in Other Agencies....................... 3-14
Conclusion...................................................... 3-14
iii
CHAPTER 4: PREPARING FOR THE DATA COLLECTION ................. 4-1
Data Collection Skills .............................................. 4-3
Where To Find the Skills You Need ................................... 4-4
Working With People From Outside the System ......................... 4-5
Conclusion....................................................... 4-6
CHAPTER 5: HOW TO LOCATE AND CAPTURE INFORMATION.......... 5-1
Jail Information Sources ............................................ 5-3
Logs and Forms................................................. 5-5
Summary...................................................... 5-7
The Problem With Data Sources—and Some Solutions.................... 5-8
Problem 1: Data Elements Are Scattered ............................. 5-8
Problem 2: Data Is Missing ....................................... 5-8
Problem 3: Information on the Form Is Wrong ........................ 5-9
Problem 4: Data Elements Are Poorly Defined ........................ 5-9
Problem 5: The Handwriting Is Illegible ............................ 5-10
Problem 6: No One Keeps Data for the Whole System................. 5-10
Setting Up an Information System for the Jail.......................... 5-10
Elements of the System.......................................... 5-10
System Startup ................................................ 5-10
Special Issue Data Collections ...................................... 5-18
Designing Special Data Collection Forms and Code Books ............... 5-19
Conclusion...................................................... 5-24
CHAPTER 6: HOW TO PUT IT ALL TOGETHER......................... 6-1
Doing the Data Collection........................................... 6-3
Determine an Overall Strategy ..................................... 6-3
Determine How Much Data To Collect .............................. 6-4
Coding........................................................ 6-7
Rules for Coding Data ........................................... 6-7
Coding in an Automated System ................................... 6-8
Gather Your Data Collection Supplies .............................. 6-10
Begin........................................................ 6-10
Automation Issues.............................................. 6-12
Conclusion...................................................... 6-12
CHAPTER 7: HOW TO ANALYZE INFORMATION....................... 7-1
What is Statistics?................................................. 7-4
Statistically Significant Differences ................................... 7-4
Probability....................................................... 7-4
Normal (Bell-Shaped) Distribution.................................... 7-5
Statistical Results.................................................. 7-6
Types of Statistics ................................................. 7-6
Descriptive Statistics............................................. 7-6
Statistics for Examining Differences Between Groups ................. 7-11
Statistics To Examine the Relationship Between Data Elements.......... 7-13
Statistical Sins................................................... 7-15
Sin 1: How Could the Results Be Wrong if the Calculations
Were Perfect? ............................................ 7-15
iv How to collect and analyze data
Sin 2: What Is the Real Average?.................................. 7-16
Sin 3: What Is Missing From This Picture? . . . . . . . . . . . . . . . . . . . . . . . . . . 7-17
Sin 4: So What if It Is Statistically Significant?....................... 7-17
Sin 5: If A, Then B? ............................................ 7-17
Sin 6: What Is Wrong With This Picture? ........................... 7-18
Conclusion...................................................... 7-18
CHAPTER 8: HOW TO INTERPRET INFORMATION ..................... 8-1
Case Study 1: The Friday Night Blues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4
Before Going on to Case Study 2.................................... 8-15
Case Study 2: The Alternative Answer................................ 8-15
Conclusion...................................................... 8-27
CHAPTER 9: SHARING INFORMATION WITH OTHERS.................. 9-1
Why Pictures Are Worth a Thousand Numbers .......................... 9-4
Methods for Displaying Data ........................................ 9-4
Tables ........................................................ 9-4
Bar Charts..................................................... 9-5
Pie Charts ..................................................... 9-6
Line Graphs.................................................... 9-6
Guidelines for Good Graphics........................................ 9-7
Rule 1: Know Your Limitations .................................... 9-7
Rule 2: Make the Graphic Illustrate the Most Important Information....... 9-7
Rule 2a: Keep It Simple .......................................... 9-7
Rule 3: Determine the Best Medium for Sharing the Information.......... 9-9
Rule 4: Decide What Scale Will Best Display the Data................. 9-10
Rule 5: Consider Who the Audience Is.............................. 9-10
Rule 6: Make the Graphic Pleasing to the Eye........................ 9-11
Rule 7: Resist the Temptation to Save Money by Putting Everything
on One Page, Transparency, or Slide......................... 9-11
Conclusion...................................................... 9-11
CHAPTER 10: GETTING THE MOST FROM YOUR
INFORMATION SYSTEM ........................................... 10-1
What This Chapter Is—and Is Not—About ............................ 10-3
A Short Course in Computers....................................... 10-4
Overview of Computer Elements .................................. 10-4
The Central Computer........................................... 10-4
Peripherals.................................................... 10-5
Communication Devices......................................... 10-5
Overview of Software ............................................. 10-5
Applications Software........................................... 10-6
A Last Word on Hardware and Software ............................ 10-7
Getting the Most Out of a Database .................................. 10-7
What To Do Before Buying or Upgrading a Computer ................... 10-8
Determine the Purpose of the Information System .................... 10-8
Define Your Needs ............................................. 10-9
System Expectations and Guidelines ................................ 10-12
The User Manages the System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-12
contentS v
The System Avoids Duplication of Effort........................... 10-12
The System Is Reliable......................................... 10-12
The System Has a Safety Net.................................... 10-12
Match the Right Application to the Task ........................... 10-12
Know How the System Handles Updated Information ................ 10-12
Format Flexibility ............................................. 10-13
Determine Internal Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-13
User Guidelines................................................. 10-13
Explore the System............................................ 10-13
Practice Analysis.............................................. 10-13
APPENDIX A: A GLOSSARY OF STATISTICAL TERMS FOR
NON-STATISTICIANS .............................................. A-1
APPENDIX B: ANNOTATED BIBLIOGRAPHY.......................... B-1
Resources for the Criminal Justice System............................. B-3
Other Resources.................................................. B-5
APPENDIX C: MANUAL DATA COLLECTION PROCEDURES AND
SAMPLE FORMS.................................................. C-1
Elements of the System............................................ C-3
System Startup................................................... C-4
APPENDIX D: INMATE PROFILE DATA COLLECTION................... D-1
Data Collection Form ............................................. D-3
Inmate Profile Data Collection Code Book ............................ D-4
APPENDIX E: INCIDENT DATA CODE BOOK.......................... E-1
APPENDIX F: TRANSPORT DATA COLLECTION ........................ F-1
APPENDIX G: TABLES FOR DETERMINING SAMPLE SIZE .............. G-1
APPENDIX H: SIMPLE RANDOM SAMPLING ......................... H-1
APPENDIX I: CALCULATING THE STANDARD DEVIATION............... I-1
APPENDIX J: CALCULATING CHI-SQUARE ............................ J-1
APPENDIX K: MANUAL DATA DISPLAY.............................. K-1
Bar Charts ...................................................... K-3
Pie Charts....................................................... K-4
Line Graphs..................................................... K-4
Graphic Tools ................................................... K-5
vi How to collect and analyze data
F o r e w o r d
How To Collect and Analyze Data: A Manual for Sheriffs and Jail Administrators
provides step-by-step instructions for local corrections personnel who want to use sta-
tistical data to improve their organization’s efficiency and provide support for funding
initiatives.
This book covers the entire process. It advises readers on what types of data they
should regularly collect, the sources from which data can be obtained, how to store data
and access it, and methods for interpreting it. Direction is given on performing these
tasks both manually and electronically.
Along the way, readers will find explanations of management techniques, methods of
displaying data, fundamental mathematics and statistics, and ways to maximize the
potential of information systems.
The appendices include a glossary of technical terms, an annotated bibliography, sam-
ple forms for data collection, and tables for determining sample sizes and generating
random numbers for use in sample selection.
How To Collect and Analyze Data: A Manual for Sheriffs and Jail Administrators has
been available since 1982. We believe this updated and redesigned edition will provide
readers with all the information they need to guide them through the complicated but
important process of collecting and analyzing institutional data.
Morris Thigpen
Director
National Institute of Corrections
vii
P r e f a c e
Who Should Use This Document—and Who Will
Not Need To
Although the title of this document, How To Collect and Analyze Data: A Manual for
Sheriffs and Jail Administrators, indicates it was written for individuals who are in
policymaking roles in corrections, it does not mean others in the chain of command—
from lieutenants to line officers—will not also find it helpful. Its concepts and content
also apply to community corrections facilities, juvenile detention facilities, and other
institutions. It will also be beneficial to people outside the jail who are involved in the
collection and analysis of jail data. Actually, the manual should be helpful to anyone
who has to gather information about jail problems, policies, and practices. How to
Collect and Analyze Data addresses both ongoing and special issue data collections
in local jails.
Those who have been involved in in-house data collections or who have crime ana-
lysts or statisticians on staff will find that many of the items covered in this manual are
familiar. This manual is not intended for criminal justice policy analysts or planners
who regularly work with statistics, information systems, or techniques like systems
analysis. However, because of its focus on the issues facing jail administrators, it may
be a useful resource for policy analysts or statisticians who are new to the criminal
justice arena.
It is particularly difficult to address issues associated with automation in this document.
Computer hardware and software are changing at an incredible rate. Whatever is said
here today will probably be outdated tomorrow. While most jails and local law enforce-
ment agencies have computers, what they have and how they use them vary tremen-
dously. Some restrict computers to National Crime Information Center (NCIC) or office
functions, like word processing. Many have “jail systems,” but their capabilities are
so varied that it is impossible to generalize. As a result, unlike the first edition of this
manual in which it was easy to assume that there were few automated jails, this manual
assumes that you have some degree of automation, but makes no further assumptions
about what kind. Rather, the manual focuses on what can be done with off-the-shelf
ix