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 Related Tools
  • Software/Tools
  • XML/XSLT

DDI 3.0 Proof of Concept for Public Review Version

The Bylaws of the DDI Alliance require the demonstration of Proof of Concept after the Public Review period for any proposed change to the DDI specification. Accordingly, we submit the following implementations to demonstrate various aspects of the effectiveness of the DDI 3.0 specification.

Conversion Tool -- DeXtris

http://www.opendatafoundation.org/tools/dextris/

DeXtris is an open source utility whose objective is to facilitate the use and understanding of XML files, particularly DDI files. It has been designed for simplicity and does not require the installation of extra components. Rather, it runs in a standard Web browser such as Firefox or Internet Explorer.

DeXtris provides basic functionalities such as a file overview and the ability to browse the document. There are DDI 1/2.x and 3.0 sample documents in the "examples" folder under the application installation directory. Opening a DDI document will allow you to quickly generate a standard data dictionary or search for variables. DeXtris can convert DDI 1/2 files to 3.0.

DeXtris was used to convert the following examples from DDI 2.1 files to DDI 3.0 files.

* In this view, mouse over the "i" symbol to see documentation for the element.

Conversion Tool -- StatsProgs2DDI (beta)

http://db.zuma-mannheim.de/DDI/StatsProgs2DDI/StatsProgs2DDI.html

StatsProgs2DDI is a tool to generate variable-level documentation in DDI 3.0 format from statistical package system files. Generating a core DDI 3.0 document from an existing system file (for example SPSS) enables a quick start in building DDI 3.0 documents. The first version of the tool includes the SPSS format, and further planned formats are SAS and Stata. StatsProgs2DDI generates the following DDI information for each variable: variable name, variable label, and common descriptive summary statistics; for each category: category value, category label, missing value indicator, and frequencies/percentages.

DDI 3.0 Stylesheets/Transforms

The following table presents DDI 3.0 examples transformed through XSLT stylesheets for display. The basic display uses a single stylesheet to transform the XML file into XHTML for Web presentation. The enhanced display passes the XML file through a series of stylesheets to add more advanced features to the XHTML display, such as graphical representation of frequencies, and automated calculation of valid percentages.

Structure Display Tool

In addition, ICPSR has created a small stylesheet that takes an existing XML document, and displays the element names used in the document, indented to represent the hierarchy. This tool is primarily of use to software developers who are building tools to work with DDI 3.0.