How to Use NACJD Data with GIS Software

The National Archive of Criminal Justice Data (NACJD) preserves and distributes computerized crime and justice data from federal agencies, state agencies, and investigator-initiated research projects to the public for secondary data analysis. Founded in 1978 as part of the Inter-university Consortium for Political and Social Research (ICPSR), NACJD is supported by the Bureau of Justice Statistics (BJS) and the National Institute of Justice (NIJ) in the United States Department of Justice.

Through the NIJ Data Resources Program, NACJD assists the Mapping and Analysis for Public Safety (MAPS) program in disseminating data and resources related to Geographic Information Systems (GIS) to practitioners and researchers in the criminal justice field.

This online tutorial highlights data collections that are freely available from NACJD that can be used for mapping and spatial analysis. In particular, it demonstrates how to find data collections of interest, how to download data from our web site, and how to prepare data files for use with GIS software. The tutorial will show examples of how to read NACJD data into ArcView 3.3, ArcView 8.1, and MapInfo Professional 6.5.

Most NACJD data collections consist of attribute data that can be added to GIS packages. There are currently very few data collections that also contain map files (such as *.shp or *.tab files). This online tutorial assumes that the user has access to map files from a particular GIS software package or from other sources, such as private vendors or the Census Bureau.

NACJD has data collections with aggregate and point-level data. The example in this tutorial uses aggregate data. Point-level data collections require the same basic steps outlined in this tutorial, plus an additional geocoding step, which is not covered here. Users should refer to the help documentation for their particular GIS software package for instructions on geocoding.

The data collection used in this online tutorial is the Uniform Crime Reporting Program Data [United States]: County-Level Detailed Arrest and Offense Data, 1999 (ICPSR 3167). These data are collected annually by the Federal Bureau of Investigation (FBI). The data are supplied by the FBI in printable tables and are aggregated to the county-level by NACJD. This data collection consists of both arrest data and crimes reported (offense) data. This tutorial will utilize the crimes reported file (Part 4) of this data collection. More information about the Uniform Crime Reporting (UCR) Program Data can be found in the online UCR Resource Guide or the PDF codebook for the 1999 data.

This online tutorial consists of four steps: