Preparing Data for Analysis: Extracting Data from Incident-Based Systems and NIBRS

This section provides an example of the programming code needed to read in a multilevel data file, to create an incident-level aggregated flat file for summary-level analysis, and to prepare individual data segments for detailed analysis. For illustration purposes, a National Incident-Based Reporting System (NIBRS) data file obtained from the FBI is read into and restructured in SPSS, SAS, and Microsoft ACCESS. The concepts illustrated are applicable to state-level data sets and transferable to other software.

The sources of incident-level data vary and the software used for data storage, reporting, and analysis varies as well. Some state statistical analysis centers use relational database software for analyses, but many criminal justice analysts use statistical software, such as SAS or SPSS. SAS and SPSS are designed primarily for analyzing data in a flat file format. Multilevel or hierarchically structured data can be analyzed in SAS and SPSS when restructured properly.

To review the basic processes and to download the SPSS, SAS, and ACCESS examples of the programming code for restructuring and analyzing multilevel data files, see the following sections:

Next: Tips and Shortcuts for Working with NIBRS Data