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What is STAC?

STAC is an acronym for the Spatial and Temporal Analysis of Crime package developed by the Illinois Criminal Justice Information Authority. STAC consists of two PC software programs the Time Analyzer and the Space Analyzer, together with accompanying user and technical manuals needed to run the programs. The STAC package was completed in 1988, with support from the U.S. Department of Justice, Bureau of Justice Statistics.

The STAC Space Analyzer is not a mapping package, but instead helps analysts who already have mapping capability. STAC is a tool to find and examine Hot Spot Areas on the map. Once you have mapped your data, you might find that there is just too much information to summarize quickly in a way that is easy to communicate to data users. STAC Hot Spot Areas provide such a summary. STAC first finds the densest clusters of points on the map (hot clusters), and then fits a "standard deviational ellipse" to each hot cluster. The analyst can then make a map showing the Hot Spot Areas. For example, you could look at the Hot Spot Areas of gang-related violent incidents and compare them to the Hot Spot Areas of gang-related drug incidents.

[ Download a packet of STAC Information (PDF file) ]


Currently, STAC is available as part of the CrimeStatII program, which can be downloaded for free from the National Archive of Criminal Justice Data. CrimeStat Version 2.0 contains an upgraded version of STAC that is fully linked with the many other spatial analysis tools available with CrimeStatII. For a general description of CrimeStatII, see the CrimeStat II Released Announcement

To download the CrimeStat II program, the manual, and a sample data set, go to: http://www.icpsr.umich.edu/nacjd/crimestat.html

Read the StacNEWS Newsletters

These newsletters about the Illinois Criminal Justice Information Authority's Spatial and Temporal Analysis of Crime (STAC) Software were published from 1993 to 1995. They contain descriptions of STAC applications, questions about STAC and advice to STAC users. The newsletter articles refer to the DOS version of STAC, not the Windows version that is being distributed as part of the CrimeStat program developed by Ned Levine for NIJ's Crime Mapping Research Center (CMRC). However, there is still some interesting and useful information about the use and interpretation of STAC Hot Spot Area analysis, that would be useful for Windows as well as DOS users.

For more information about the CrimeStat version of STAC, see the CMRC CrimeStat web site, at http://www.ojp.usdoj.gov/nij/maps/, click on "Mapping Tools" then on "CrimeStat 2" or visit http://www.nedlevine.com/nedlevine17.htm


What does STAC do?

STAC was created in response to requests by local law enforcement agencies for improved crime analysis capabilities. Its primary purpose is to locate clusters of criminal activity in a community by automating such analytical functions as time-of-offense data analysis and manual pin mapping.

STAC supports law enforcement agencies with crime analysis, administration, long-range planning, tactical decision-making and other activities.

How does the Time Analyzer work?

The Time program helps determine the most likely time of day and day of week that a particular type of crime will occur, even when the information available to police is imprecise.

How does the Space Program work?

STAC Hotspot Example

The Space program helps find those areas in a community where there is a concentration of crimes -- hot spot.

It is not a mapping package. Users of Space must have computer mapping capabilities and geocoded "pin map" data to use in conjunction with STAC.

After the program calculates statistical summaries such as the Hot Spot Area, the user maps the results with a mapping package. STAC users are currently mapping with MapInfo, ArcView/ArcInfo, Streets-on-a-Disk and ATLAS.

When is STAC most useful?

STAC’s Time and Space programs are most useful when local law enforcement agencies use them is tandem with other investigative tools to prevent and solve crimes.

STAC can provide useful information for broad planning purposes as well as specific tactical decisions.

Who should use STAC?

STAC can improve the performance of almost all functions within a local law enforcement agency. Police administrators can use STAC to gather summary crime information for internal planning sessions or public meetings. Police planners can use it to respond to changes in incident patterns over time.

Managers can use STAC to determine patrol sector divisions, and shift supervisors can use it to make decisions about when to schedule shift changes. Crime analysts can use STAC to help solve individual crimes. Traffic officers can use STAC to study traffic accident patterns, while foot patrol officers can use it to plan shift activities.

How much does STAC cost?

The Illinois Criminal Justice Information Authority and Bureau of Justice Statistics are making STAC available to law enforcement agencies at no cost.

What is the current STAC format?

STAC is currently in DOS—users need DOS 3.0 or higher—but a Windows version is currently in development.

How do I order STAC?

To request STAC, send us a letter outlining your need for it, reviewing the type of mapping and database systems you currently have, and agreeing to become part of the STAC user network and help other users.

Also, download and mail us a completed STAC contract that assures you will not sell the package and that you will cite the Authority in any reports or publications using STAC analysis.

Mail to:

Attn: STAC
Illinois Criminal Justice Information Authority
120 South Riverside Plaza, Suite 1016
Chicago, IL 60606

How do I join the STAC User's Forum?

Either include your e-mail address with your completed STAC contract or send a message to: bblock@icjia.state.il.us. Users will receive their forum ID and password via e-mail. The STAC forum allows registered users to download STAC software and manuals, view progress reports and screenshots for the upcoming STAC for Windows, share STAC maps and research with other users, and assist other STAC users with technical questions.