DDI Tools Made Available by the SDA Project
CSM Program, Univ. of Calif., Berkeley

Converting DDI (version 2) to DDL

SDA provides an online DDI to DDL Conversion Service. You can upload DDI files from your computer to the conversion service's computer, choose various options, then download the resulting DDL file.

Creating DDI (version 2)

The basic strategy represented here is to break up the task of generating DDI documentation into separate stages.

Note that these tools are under development and will be changing from time to time.

Study-level Information

Strategy: Copy study-level information from an existing DDI file and then use a text editor to modify it for other studies.

There are many DDI examples in the ICPSR archive.

Variable Specifications

Strategy: Start with some existing variable definitions, and convert them into DDI variable specifications.

• XCONVERT program
  Convert SAS, SPSS, and Stata data definitions to DDI.
  The XCONVERT documentation also explains how to convert an SPSS system file into an ASCII data file and a matching DDI file.

• DDLTOX program
  Convert SDA's data description language (DDL) files into DDI variable specifications.

• SDATOXML program
  Convert SDA system files into DDI variable specifications, including frequencies and statistics.