The Data Documentation Initiative is an international effort to establish a standard for technical documentation describing social science data. A membership-based Alliance is developing the DDI specification, which is written in XML.
The Data Documentation Initiative (DDI) is an effort to create an international standard in XML for metadata describing social science data. The Alliance is a self-sustaining membership organization whose members have a voice in the development of the DDI specification.
The Data Documentation Initiative (DDI) is an effort to establish an international XML-based standard for the content, presentation, transport, and preservation of documentation for datasets in the social and behavioral sciences. Documentation, sometimes called metadata (data about data), constitutes the information that enables the effective, efficient, and accurate use of those datasets.
The ability for scientists to exchange data is widely recognized as key to scientific progress. That ability critically turns upon the existence of documentation that enables a new analyst to gain a full understanding of the data without any consultation between the data collector and the analyst. There is widespread agreement among data archivists in the social sciences that extant forms of documentation are often inadequate for this purpose. Indeed, data archives have historically faced larger problems with the documentation of their data than with the data themselves.
In response to the need for better documentation, the Data Documentation Initiative (DDI) is an endeavor to provide a straightforward means for social and behavioral scientists to record clearly and then to communicate to others all the salient characteristics of the empirical data for which they are responsible. The DDI metadata specification originated in the Inter-university Consortium for Political and Social Research and is now the project of an Alliance of about 25 institutions in North America and Europe. Together, the member institutions comprise many of the largest data producers and data archives in the world. Virtually every kind of body of data is found in one or more of the archives.
The DDI specification is a major transformation of the once-familiar electronic "codebook," retaining all of the capabilities of that kind of document but greatly increasing the scope and rigor of the information contained in it. Indeed, the DDI metadata can be displayed as conventional paper or screen codebook-like documents, but unlike the old codebooks, the information displayed can be fully understood by computer software as well as by humans. The DDI transforms the concept of codebooks by encoding codebook information into databases that share a known structure and a specification language across many bodies of data.

The DDI aims to be the foundation for collection, distribution, use, and archiving of many future data collection projects in the social and behavioral sciences, across institutions, countries, and disciplines. It also aims to be the basis for retrofitting documentation of older studies for improved ease of use and stronger guarantee of archival preservation. The latter aim requires that this new specification be independent of any particular software or computing platform; this has been achieved by conceiving the specification as a generalized data model rather than as computer code. The data model is extensible and modular, supporting the specification of even the most complex data systems in a way that is simultaneously flexible and rigorous.