SDA allows you to conduct statistical analysis quickly and efficiently on the Internet using your Web browser. The software powering this system, developed by the Computer-assisted Survey Methods Program at the University of California at Berkeley, is called Survey Documentation and Analysis (SDA).
SDA allows you to manipulate and analyze data without downloading files or using specialized statistical software. SDA performs a wide range of statistical analyses, from bivariate crosstabulation to multiple regression and analysis of variance. SDA allows users to design and implement custom recodes as well as generate subsets of data for download and analysis with traditional statistical applications.
For more information on all SDA features, see the Users Guide.
Also see the NACJD SDA page to learn more about the datasets that are available for online SDA analysis and to learn how to search for specific variables across datasets.
The data set Capital Punishment in the United States, 1973-2004 is used as an example throughout the tutorial.
The Capital Punishment in the United States, 1973-2004 data file contains more than 8 thousand cases (records). The study records the movement of prisoners onto and off of death row starting in 1973. In order to examine particular cases (individuals) it is necessary to correctly specify the selection criteria. In addition, for certain analyses it is necessary to sort the data file before making selections.
Some individuals are included in the data file more than once. Typically this occurs when someone has been sentenced to death, subsequently had his sentence overturned, and then again sentenced to death. These people have the same identification number in the data set. In order to avoid double counting, BJS tables include only the latest death sentence. The issue of double counting arises most often when the flow of prisoners onto and off of death row is being analyzed.
View a summary of the Capital Punishment in the United States study.
Continue to the SDA Codebook Tutorial