OVC ArchiveOVC
This file is provided for reference purposes only. It was current when produced, but is no longer maintained and may now be outdated. Please select www.ovc.gov to access current information.

CRIME MAPPING (continued)

Getting Started

It is easy to talk about what GIS will do, but getting started is another matter. Recognizing this, there are a couple of steps to consider. First, obtain training for staff who will introduce GIS technology to all levels of your agency. Coordinate presentations on what GIS is and what it can do.

Remember, thinking spatially about data is a learned skill. If you spend time teaching the basics of GIS and generate some enthusiasm about the concept, you can avoid a lot of confusion and reluctance down the road. Remember, GIS is a tool that enables an agency to make better use of the data it is already collecting.

Second, perform a needs assessment. A needs assessment is simply a methodological evaluation of an agency’s existing needs, resources, and goals. It is a structured approach by which an organization is prompted to ask the right questions when considering implementing a GIS system. Some basic questions to consider are highlighted below.

What Are the Needs and Goals of Our Agency?

To build a GIS system to address the needs of your agency, you must first identify those needs. How will you use GIS? Will you use it to support management decisions, to evaluate existing initiatives and projects, and/or as a predictive modeling tool to identify the location of future subgrants? You can use a GIS system for all of these purposes and more, but knowing what you want to do before you begin will help you define the data needed to support the application.

What Types of Queries Do We Want Supported by the GIS Application?

If you purchase an off-the-shelf GIS software package, the system likely will contain an ad hoc14 type of querying capability. In other words, any data that you have loaded or integrated into the system can be accessed and queried. However, you may choose to customize the application to address your specific needs. For example, here are two types of query options: One is the ad hoc query used by ArcView 3.1 (exhibit 17) and the other is a screen shot of a customized query15 built for Connecticut’s New Haven Police Department (exhibit 18).


Privacy and Confidentiality

NIJ’s MAPS, through a contract with the Institute for Law and Justice (ILJ), developed the guide Privacy in the Information Age: Guidelines for Sharing Crime Maps and Spatial Data to address privacy and data confidentiality when using GIS. The report is available for downloading from ILJ’s Web site at www.ilj.org, and hard copies are available from NIJ. The guidelines discuss options and requirements for addressing privacy, confidentiality, and data sharing and address concerns about the dissemination of geocoded data and the balance between the public’s right to know and the victim’s right to privacy. The report outlines some of the mechanisms and techniques used to protect privacy and provides Web resources for online mapping efforts.

As you can see, a generic query builder is much more flexible but requires more technical expertise and knowledge about the data. A customized query builder requires less training but is more data restrictive. The user only has access to the data fields defined by the drop-down menu. In the New Haven query menu, users can access several tables but are limited to the particulars of the crime, date, age, time, and day of the week. However, the tables contain much more information than what the menu is displaying (exhibit 18).

What Are Base Maps and Where Can We Get Them?

Base maps are the foundation of a GIS. Typically, they comprise a street centerline and a geographic backdrop such as the census tract, ZIP Code, and/or county and state boundaries. Street centerlines of almost every city, state, or region can be purchased from vendors or downloaded free from the Internet by accessing the U.S. Census Bureau TIGER Files at www.census.gov. TIGER (Topologically Integrated Geographic Encoding and Referencing) is a nationwide, seamless, digital map. Most city information systems departments or planning departments also have centerline files they may be willing to share, especially with other government agencies or nonprofit organizations. These locally generated centerline files tend to be more accurate and detailed because they are created at the local level and are updated more often than the Census Bureau’s.

What Additional Data Needs To Be Collected To Support the Application?

In addition to using your own data, you may want to integrate additional data from other sources, such as census figures, law enforcement data, and transportation information. VOCA administrators may choose to collect and share information across state boundaries and between compensation and assistance programs to minimize repetition and duplicate efforts. Some agencies will share information about a case or a person depending on how relevant it is to their agency and privacy concerns. Of course, any information shared should not be identifiable to a specific individual. The only instance in which this should occur would be if more than one agency is working with crime victims and the information sharing is allowed by state law or by informed consent of the victims.16

What Are Our Data Formats and How Can We Integrate Disparate Datasets?

Mapping systems can integrate various data formats.17 However, the most common format is that of a database file, a file extension ending in .dbf. Fortunately, most spreadsheet tables can be converted easily to database files to make them ready for integration into a GIS. You can usually convert them by choosing “save as” under the file drop-down menu of your software, choosing a .dbf file extension, and following the steps prompted by the application.

Although creating a database warehouse for GIS would involve the input of a multitude of data, it would eliminate redundant data collection by agencies. A VOCA database could contain information on crime incidents, victims and offenders, locations of subgrantee recipients, compensation recipients, victim services programs, census data, and jurisdictional and state boundaries. Obviously, data from various organizations will exist in differing formats, but recent technologies make data conversions very easy.

Is Our Data Accurate and Timely?

It is critical that you know your data before using it in GIS. For example, does your community have a Martin Luther King Boulevard? If so, how is it listed? MLK Blvd., Martin Luther King Street, MLK Jr., or another variation? All these options are correct, but their variation may create difficulties when you try to geocode your data. This is a problem many users face when they begin to use their data in a spatial environment. Most agencies have been collecting address-level data for years. Generally, the quality of this data has been left to the discretion and integrity of the person entering the data. The accuracy and standardization of this data will contribute to the overall ease or difficulty with which the data is integrated into your GIS. Another issue to consider is the timeliness of data. Street files may only need to be updated once a year, depending on the construction in the community, but records containing crime incidents, arrests, and claims and subgrant award data may need to be updated more frequently.

What Are Our Hardware and Software Requirements?

Some of the above questions can be answered by staff members who are familiar with the data your agency collects. However, when it comes to hardware and software requirements, it is better to consult with information technology (IT) professionals who can help you define your GIS requirements based on your business needs and budget. IT professionals can help identify the technical needs involved with implementing a GIS. For example, a GIS can be implemented on the Internet, the Intranet, or as a stand-alone application loaded on an agency’s personal computer (PC). IT professionals can tell you whether you should add more PCs to your department, install larger transmission lines for faster data transfers, or increase the RAM (random-access memory) and hardware space on your existing PCs. They can also evaluate your assets. Do you have an Intranet that can be used, firewalls in place for confidential data, or other types of security that can be accessed such as password-protected applications? Other issues to be addressed in a needs assessment include training for users, the experience of support personnel, system maintenance, and software licenses.

The GIS package purchased for your program will have greater use if it is compatible with that of other agencies’ data. For efficiency’s sake, purchase software that can easily export and import GIS files into the appropriate software packages. VOCA administrators and subgrantees within the same state should purchase systems that use the same format for storing data to significantly reduce duplication of effort.

Building a GIS from scratch takes time, effort, and experience, but with today’s off-the-shelf desktop mapping applications, developing and customizing a system to address specific organizational goals is relatively routine.

Previous Contents Next

Using Geographic Information Systems To Map Crime Victim Services:
A Guide for State Victims of Crime Act Administrators and Victim Service Providers
February 2003
Archive iconThe information on this page is archived and provided for reference purposes only.