Crime Mapping Research Center

On February 3-4, 1997, the National Institute of Justice (NIJ) brought together over 30 experts to discuss the role that its newly created Crime Mapping Research Center (CMRC) should play in advancing the state-of-the art in spatial analysis and computer mapping for criminal justice agencies. The meeting took place in Washington, D.C. under the direction of Dr. Nancy La Vigne, CMRC Director. As she explained, specific aims of the CMRC include the following:

The CMRC will be housed at NIJ in Washington, D.C. with the possibility of establishing a satellite office in Denver, Colorado. The National Law Enforcement and Corrections Technology Center, Rocky Mountain Regional Center, in Denver has been provided a grant to assist NIJ in its mapping effort. They were selected because they were already knowledgeable about mapping technologies and have established ties with the University of Denver.

Dr. La Vigne indicated that some of the specific activities under consideration for the CMRC are to (1) establish a training center for summer workshops on crime analysis, (2) archive geocoded crime data, (3) promote partnerships with neighboring police departments to share information, (4) promote mapping for criminal justice applications other than crime, (5) promote more analytic tools, and (5) partner with corporate vendors to develop software. She also indicated that the CMRC was developing a survey of police departments to determine what they are currently doing with crime mapping, what systems they are using, and where they are headed with their mapping technologies.

Dr. La Vigne stated that she asked for this meeting in order to get guidance from experts across the country on how the CMRC can achieve its aims. The meeting's format called for a series of presentation by selected attendees with time provided for discussion. Presentation topics included development of new spatial and temporal analytical tools, forging cross-jurisdictional partnerships, confidentiality issues with geocoded crime data, and applications of analytical mapping for criminal justice agencies. The second day provided time for breakout sessions to synthesize ideas for the CMRC to consider.

These proceedings have been developed around the aims of the CMRC and the ideas expressed by attendees at the meeting. The format is by topic area rather than the chronological order of talks at the meeting. The final section provides a summary of the implications for the future activities of the CMRC.

Data Issues

Several issues about spatial data emerged during the two days of the meeting. Of particular concern were the following three issues:

Each of these issues is discussed in the following sections.

Address Matching

Address matching consists of taking the addresses in a database and converting them to x-y coordinates. It is an essential precursor to spatial analysis. All geographic mapping computer packages come with a geographic base file (geobase file) for the user's jurisdiction and have a built-in routine for matching addresses against the geobase file to determine coordinates. The file contains the cartographic data necessary for producing a map, as well as attributes of the geography represented by a map, such as address ranges of a street segment, intersections of streets and boundaries of geographic areas. The most common geobase files are the TIGER files developed by the Census Bureau for the 1990 census. TIGER files contain topological data structures describing how points and lines relate to each other on a map to define geographic areas, such as census tracts.

As expressed by several attendees, the problem is that when first acquired, TIGER files and other geobase files usually are highly inaccurate. For example, numerous changes to streets will have occurred in a city since the 1990 census. Users must therefore spend a considerable amount of time correcting the geofile and adding new streets before any mapping or spatial analysis can be accomplished. A related problem is that the addresses in a database may be in the wrong format or may contain errors causing mismatches with the geofile. In either case, analysts in some cities have to spend an inordinate amount of time cleaning the data and correcting the geofile to such an extent that they have little time for analysis.

While there have been problems in the past with TIGER files, Mr. Phil Canter stated at the meeting that the new TIGER 2000 being developed by the Census Bureau and the United States Postal Service for the next census will be a significant improvement. He also noted that private corporations are also developing GIS software and new uses for this technology. He suggested that partnerships should be developed with these corporations to take advantage of their innovations.

As indicated by some attendees, an alternative that has been successful in some cities is to use a geofile that has been developed locally by another city or county agency. For example, the city's planning department or transportation department may have a better and more accurate geobase file.

National Incident Based Reporting System

The National Incident Based Reporting System (NIBRS) was developed approximately ten years ago to enhance the quality of crime statistical data collected by police departments. The long-term view of NIBRS is that it will replace the Uniform Crime Reporting (UCR) program that has been in place since 1930. NIBRS is viewed by its supporters as a significant improvement over the UCR system because it provides more detailed and accurate information about individual crime incidents. Both systems are supported by the Federal Bureau of Investigation (FBI).

Participation in NIBRS is voluntary. Until a police department is ready to participate, it can continue to submit crime information in accordance with the requirements of the traditional UCR Program. Moreover, as stated in NIBRS documentation from the FBI,

NIBRS data is to be generated as a by-product of state and local incident-based reporting (IBR) systems. This means that a state or local agency may build its IBR system to suit its individual needs, i.e., it can have a different file structure than that used by the National UCR Program and include additional data elements and data values. However, when it is time to report to the National UCR Program, the state or local agency should extract from its IBR system only the data required by NIBRS and record it onto magnetic tapes in NIBRS' format for submission for the FBI. (Volume 1: Data Collection Guidelines, National Incident-Based Reporting System, FBI, July 1988).

At the meeting, there was considerable debate about the utility of NIBRS and about what the CMRC should be doing in regard to NIBRS. Some attendees believe that will never be adopted by police departments while others stated that NIBRS was already the national standard. Comments from attendees reflect the diversity of opinions expressed at the meeting:

Most attendees believed that the CMRC should take a stand in regard to NIBRS, but as indicated by the above comments, they were divided on what that stand should be. It was also noted that SEARCH Group, Inc., in Sacramento, California, is a completing a study for the Bureau of Justice Statistics (BJS) on how to improve NIBRS and have more police agencies adopting it. It was suggested that Dr. La Vigne should obtain a copy of the study as a precursor to what the CMRC should do.

Data Confidentiality

Advance in computer hardware and software has meant that spatial analysis and mapping has become more accessible to a variety of users. Criminal justice organizations, the police in particular, have embraced this methodology because it has given new insights and measured information for improving the delivery of services, and, in general, enhancing organizational effectiveness and efficacy. Recently, it has been advocated that the synergistic effect could be realized by kindred organizations using this technology through the sharing of information and data. Simultaneously, for almost the same reasons, independent and sponsored research efforts pertaining to the spatial analysis and mapping of criminal justice phenomena has increased in popularity.

An important outcome of these new ventures pursued by applied and basic research efforts has been the creation, acquisition, and archiving of spatial data which are different from traditional forms of data and information. Yet, confidentiality concerns are similar for both forms of data. For this discussion, Dr. Taylor presented three sets of questions. The first set pertains to confidentiality issues: How do we apply human subjects protections to spatial data? In what fundamental ways are geocoded data different from other forms of data? In what way does geocoded data raise ethical questions differently? The second set of questions reflect concerns regarding the acquisition, exchange, or release of data: What are the stipulations and requirements asked of each reporting agency and researcher for accessing, and releasing data? How does NIJ as an archiving agency use the data? How are the data handled by other user groups? The third set of questions are more specific and are concerned with minimum standards that allow data to be useful for research and decision making while maintaining confidentiality safeguards. What is the nature of time and space identifiers? What are the minimal useful and compliant spatial, temporal, and space­time scales? Are these minimum standards the same for all types of reported crime? What is the methodology for arriving at decisions that maximize the utility of data while minimizing potential harms?

Dr. Taylor pointed out that the significant difference between spatial and traditional crime is that in the latter all personal identifiers are removed, yet with the former while personal identifiers are absent there is a geographic or locational identifier. Thus, the issue is if such an identifier is likely to breach confidentiality requirements.

The comments from the panelists reflected five areas of concern: Data Sharing and Sensitivity; Exploitation of Data; Different Data Needs; Secondary Data Analysis; and NIJ As A Data Archive.

Data Sharing and Sensitivity Precautions should be observed in the sharing of data between agencies and other interested parties. Particularly, if specific victim information is involved or if information has become sealed in court records.

Exploitation of Data Sensitive and confidential data are one issue, but another is enhancing access to seemingly public information that could be used for exploitative purposes. One entity that was repeatedly mentioned as a source of concern was the real estate industry.

Different Data Needs The point was discussed that academics and practitioners have different data requirements. Thus, there is the potential that restrictions on data identifiers may make the analysis of the data a greater prohibitive problem rather than getting access to the data.

Secondary Data Analysis The point was made that concerns about confidentiality, sensitivity, and exploitation of data are only pertinent for secondary data analysis. Because the original collectors and users of the data initially struck a deal with the agencies for access that was mutually accepted. Furthermore, the reality is new technology has made agencies more open to outside researchers and their data more accessible.

NIJ As A Data Archive Many comments alluded to NIJ, in general, and the Crime Mapping Research Center, in particular, assuming the role as a spatial crime data archive. Therefore, the archiving function in general became the focus for discussion.

One panelist advised that archiving is not solely for the purpose of enhancing access to data, but for conservation and maintenance of an historical record as well. When do you archive? was another question raised. Specifically, should raw or processed data be archived? Or both? Finally, since maps store information in a spatial format, should they not be archived as well.

The archiving function will require further review and deliberation. Decisions will have to be made regarding types of data for archiving and the conditions for access.

Geographic Information Systems

Dr. George Rengert gave a presentation at the meeting that centered on the potential of Geographic Information Systems (GIS) to revolutionize the criminal justice system. He cautioned that researchers in past revolutions of the social sciences, such as the "quantitative revolution," have attempted to distance themselves from practitioners. They tried to "mystify" their approach and dismiss the uninitiated. Dr. Rengert strongly urged that today's researchers should make GIS technology as understandable as possible to practitioners, indicating that there was no need to add complexity when it is not needed.

In terms of GIS applications in criminal justice, he stated that it has tremendous potential for theoreticians and practitioners. The GIS perspective can bring new insight into spatial problems that are excluded from current statistical packages. However, within criminal justice, GIS is in its infancy. Much of the work to date has been descriptive, such as geographical profiling. Although the criminal justice system could benefit from the strengths of GIS, the technology has only started to be applied.

Responses from attendees included the following:

As Dr. Rengert continued his presentation, he indicated that practitioners are finding many uses for GIS from simple address matching to global positioning to crime pattern analysis. At the micro level, point pattern analysis has been applied to serial offenders. At the macro level, researchers have analyzed crime displacement. Other analysis has evaluated the spatial arrangement of arrests with calls for service. This analysis brings us to the practical question of how much GIS should be used to monitor police patrol operations? Is it technologically possible to track the movement of patrol cars while on duty and is this a good idea? Will police want such a device or will they feel that "Big Brother" is watching their every movement.

Participant comments were along the following lines:


During the two-day meetings, numerous computer mapping applications were mentioned and several were discussed in depth. The applications can be divided into two very general categories. One set are applications that currently exist and are prevalent in many agencies. These include "hot spot" analysis of crime patterns, designs of police beats, basic mapping for community meetings, crime mapping for COMSTAT meetings (in New York City with adaptations in several other cities), and many others. A second group are currently under development in a few criminal justice agencies and include pattern analysis of serial offenders and delivery of mapping results to patrol officers on the street.

The second group of applications under development elicited more comments at the meeting because an aim of the CMRC is clearly to assist in developing new applications for the field. For this reason, the following sections summarize three presentations at the meeting to show the direction that the field may be taking and the role that the CMRC may take in the future.

Geographic Profiling

Dr. Kim Rossmo from the Vancouver, Canada Police Department gave a presentation on geographic profiling. He defined geographic profiling as an information management strategy for serial violent crime investigations. Suitable crimes for this type of profiling are serial offenses, predatory crime, and multiple location crimes. Geographic profiling is based on research in a variety of disciplines including criminology, geography, forensic psychology, cognitive mapping, mathematical modeling, statistical analysis, and criminal investigation. According to Dr. Rossmo, "You never know where you're going to get an idea from and you need to step outside of your discipline sometimes."

Dr. Rossmo explained that the process of geographic profiling involves the following activities:

As Dr. Rossmo explained, most crimes are not random, but are usually selected by their perpetrators. Drs. Paul and Patricia Brantingham have suggested that target selection follows a "distance decay function." That is, there is a buffer zone around an perpetrator's home within which he or she does not commit offenses. He gave several examples based on arrests of serial offenders to illustrate his points. The basic approach is that a pin map is first developed of offenses with common characteristics and a mathematical probability map is developed based on a distance decay function. The results are then superimposed onto a street map to indicate the area in which the perpetrator lives or might strike again.

He emphasized that geographic profiling does not give an "X" that marks the spot where the offender is located, but instead give an optimal search area. After producing such a map, several investigative strategies can be pursued, including patrol saturation, static surveillance, outside agency information, task force suspect lists, door-to-door canvasses, and others.

The Vancouver Police Department is currently developing an automated system to support geographic profiling.

Information System for Crime Analysis Mapping

Sergeant Jonathan Lewin from the Chicago, Illinois Police Department gave a description of the crime mapping tool that is now available to officers in the field. The system is called the Information System for Crime Analysis Mapping (ICAM). The system maintains about three months of crime data on hand and can be run on any computer that uses Windows software. Patrol officers have been issued small laptop computers for operating the system. ICAM is very user friendly and can be used with assistance of a mouse rather without keyboard interaction.

ICAM has given the Chicago Police department access to crime information in a more rapid fashion than as ever existed in the department. It allows officers to develop their own map. A user selects the search criteria, sets a variety of parameter, and a MapInfo grid then appears with the information. The system allows the user to customize any map with a variety of options and the database for the system is updated daily.

At the time of the conference, a second version of the system called ICAM II was under development at the department. ICAM II will provide for holding two years of crime data. Users will have access to arrest data and will be able to generate maps of arrestees. It will also have more search parameters. All programming for ICAM and ICAM II was done within the police department.

COMSTAT in the New York City Police Department

Assistant Commissioner Phil McGuire from the New York City Police Department provided attendees with a demonstration of the COMSTAT system developed in the department for making commanders more accountable for crime in their precincts. According to Mr. McGuire, COMSTAT allows the following computerized analyses on line:

All of these are based on parameters provided by a user. Other characteristics of the system include the following:

Mr. McGuire noted in closing that the department is currently developing more advanced spatial analysis techniques under a grant provided by NIJ. The grant is a partnership between the police department and geographers at Hunter College, City University of New York.

Criminal Justice Applications

Throughout the two-day meeting, there was a natural tendency for attendees to discuss applications for police departments to the exclusion of applications for other criminal justice agencies. This tendency can be attributed to the fact that more research and applications have been developed for police. However, several attendees noted the importance for the CMRC to expand its horizons to include all agencies. In line with that train of thought, a presentation from Mr. Steve Van Din, Chief, Division of Research, Ohio Department of Rehabilitation and Corrections provided insights into how mapping might be used in the correctional field. His examples pertained primarily to offender management and monitoring, policy analysis, and resource planning.

Offender Management and Monitoring. Epidemiological mapping has been used to ascertain the origins of TB and HIV positive inmates. Gang affiliations of inmates are determined by examining community of origin, hence cell assignments are made in order to minimize conflicts. In the community, GIS and GPS (global positioning system) can be used for geographically electronically monitoring parolees. For example, pedophiles could be monitored and their locations examined in relation to schools and other child rich environments. Likewise, the locations of spouse batterers could be monitored in relation to the locations of their victims.

Policy Analysis. Mapping was used to examine the impact of proposed legislation to incarcerate certain people who are within 1000 feet of a school. The analysis showed that 75% of Cincinnati, Ohio's residents live within 1000 feet of a school. Such a policy would have been costly if adopted, hence the legislation was canceled..

Another potential application revealed by Mr. Van Dine concerns examining the neighborhood characteristics of the residences of offenders. Since, most offenders come from high crime areas mapping could help in anticipating the impacts of requiring parolees to reside in a different, presumably less criminogenic neighborhoods.

Resource Planning According to Mr. Van Dine assessing the county origins of all the inmates in the Ohio Correctional System was an arduous task until mapping was employed. Time was saved because the inmate origin data could be automatically processed and mapped and the drawing tools in the software made composing final maps an easier task..

In community corrections mapping technology can be used to examine the residential locations of parolees in an effort to more optimally allocate or assign correctional and social services. Furthermore, the same methodology can be useful for examining parole officer safety by estimating the number of officers that should be assigned to visit specific types of clients and/or places.

After Mr. Van Dine's presentation, other participants made the following comments and suggestions about mapping applications in corrections:

After the presentation, Dr. La Vigne asked how courts could use mapping systems. Several suggestions were forthcoming:

Linking with Practitioners

This discussion was led by Mr. Phil Canter, Baltimore County, Maryland Police Department and focused on strategies and issues involved with forging partnerships between and among academia, government agencies, businesses, and the public for the purpose of working together with police departments in fulfilling their missions of preventing and suppressing crime. Mr. Canter began the discussion with an overview of how the emphasis on productivity and doing more with less has influenced many public agencies, in general, and police, in particular, to utilize technology for improving the delivery of services. Computer technology utilizing mapping for crime analysis has great potential for being very effective if there is intra­ and inter agency sharing of information, because geography is the common link to everyone's databases. Four general topical areas or themes emerged during the discussion: resource problems; technical problems; credibility and constraints; and standardization.

Resource Problems. Many police agencies are willing to try new technology for delivering their services and to enter into collaborative arrangements but they do not have the resource base to purchase hardware, software, and hire or train qualified personnel. Therefore, the problem is one of accessing the technology. This situation is particularly endemic to small police departments.

Technical Problems. Numerous testimonials were issued pertaining to the myriad of technical problems in assembling databases. People do not realize how difficult it is to bring together different data sets from a technical standpoint. Partnerships have been formed to integrate data sets from multiple jurisdictions, but integrating data within a single agency can be a major technical challenge. Regardless of the political and inter­organizational matters that have to be addressed for forming partnerships­the technical problems can be a major obstacle.

Credibility and Constraints. There was general agreement that arrangements or partnerships enabling crime analysts to examine data across neighboring jurisdictions was a promising and worthwhile goal. However, there was discussion about potential problems with key agency personnel becoming disenchanted with partnerships if there was no tangible or useful output from the collective efforts. A partial solution to this problem would be the development and dissemination of new tools and research that goes beyond theory and is focused on being applied to operational, policy, and decision making problems.

Implications for The CMRC In addition to promoting partnerships through their grant initiatives, It was suggested that NIJ and the CMRC could be instrumental in: developing and disseminating tools for small police agencies; acquiring and linking spatially based data sets from other disciplines; fostering communications among spatial researchers from other disciplines; and training the trainers regarding the application and use of different techniques and tools.

Relationships with Vendors

Several attendees felt that a major constraint with mapping products from commercial vendors is that they are not designed for criminal justice applications. Most of their customers are from the business world. This observation prompted the suggestion that the CMRC could bring vendors into the partnership arrangements. It was felt that vendors might be more responsive to police and other criminal justice users if the CMRC could establish a standard set of spatial analysis and mapping tools.

Computer mapping and spatial analysis have become so popular so fast that the knowledge base for defining them to new users has emanated from the literature provided by the software vendors rather than from geographers and analysts in the criminal justice field. As a consequence, information provided to practitioners is on a general and technical level that is not specific to this field.

Implications for the CMRC

At the end of the first day of the conference, attendees were divided into groups to discuss the presentations that had proceeded and to generate ideas for the future direction of the CMRC. The next morning these ideas were discussed in a closing session as input for further consideration by NIJ. The following is a compilation of breakout group recommendations as compiled by Dr. La Vigne.