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Last modified: June 27, 2000
Data Documentation Initiative: A Project of the Social Science Community

[June 27, 2000] "The Data Documentation Initiative (DDI) is an effort to establish an international criterion and methodology for the content, presentation, transport, and preservation of "metadata" about datasets in the social and behavioral sciences. Metadata (data about data) constitute the information that enables the effective, efficient, and accurate use of those datasets. In the social sciences, metadata are often called "codebooks," although they have not literally been books for many years. With the achievements of the DDI, codebooks can now be created in a uniform, highly structured format that is easily and precisely searchable on the Web, that lends itself well to simultaneous use of multiple datasets, and that will significantly improve the content and usability of metadata. Further, this specification may have far-reaching implications for improvement of the entire process of data collection, data dissemination, and data analysis. Initially with support from the Inter-university Consortium for Political and Social Research (ICPSR) and then with support from an NSF grant (SBR-9617813) (and considerable in-kind contributions of staff time from institutions all over the world), the DDI committee has produced what is known as a Document Type Definition (DTD) for "markup" of social science codebooks. The DTD employs the eXtensible Markup Language (XML), which is a dialect of a more general markup language, SGML."


  • DDI Project Home Page

  • DDI Project Introduction

  • DDI DTD Version 1. [cache]

  • DDI Tag Library. "This page links to sites describing the five main sections of the Document Type Definition (DTD) for social science data documentation developed by the Data Documentation Initiative (DDI) Committee. These documents present English language descriptions of XML (eXtensible Markup Language) DTD elements and attributes and instructions for their use as of Version 1 (Final) by Jerome McDonough, UC-Berkeley Library."

  • A graphical representation of the document hierarchy.

  • Single File Tag Library. [cache]

  • [June 26, 2000] "Providing Global Access to Distributed Data Through Metadata Standardisation. The parallel stories of NESSTAR and the DDI." By Jostein Ryssevik [Submitted by The Norwegian Social Science Data Services]. Paper given at the UN/ECE Work Session on Statistical Metadata, Geneva, Switzerland, 22-24 September 1999. "The paper tells the parallel and highly interlinked stories of two initiatives originating in the world of social science computing, the DDI and NESSTAR. The first of these acronyms represents a concerted effort among data archives and data providers in USA, Canada and Europe to develop a metadata standard for social science data resources (the Data Documentation Initiative). The second belongs to a European based software development project that uses this emerging standard as a platform to provide on-line access to huge amount of distributed data over the Internet (Networked Social Science Tools and Resources). An XML DTD (Document Type Definition) provides the rules for applying XML to a document of a specific type. The DTD defines the elements that the document is composed of, the attributes of these elements, and their logical relationships to other elements. The elements will usually be arranged in a hierarchical or tree-like structure. The DDI-tree contains five main branches, or sections: [1] The document description, which describes the metadata document and the sources that have been used to create it (this section can thus be looked upon as a kind of metadata for the metadata , or mete-metadata if you like). [2] The study description, which contains information about the entire study or data collection (content, collection methods, processing, versioning, sources, access conditions etc). [3] The file description, which describes each single file of a data collection (formats, dimensions, processing information, missing data information etc.) [4] The variable description, which describe each single variable in a datafile (format, variable and value labels, definitions, question texts, imputations etc.) [5] Other Study-Related Materials, which can include references to reports and publications, other machine readable documentation that is relevant to the users of the study (referenced by URIs) etc."

  • Proposed Structure of the DTD Codebook.DTD invokes an XML version of the Exchange Tables Model (CALS) [local archive copy]
  • Original Codebook.DTD
  • Data Documentation Initiative Beta-Test Call for Participation
  • DDI Committee Members
  • Contact:
  • The Data Documentation Initiative - as SGML

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