History of DDI

The Data Documentation Initiative (DDI) has facilitated the description and documentation of data for over 30 years. What began as a focused effort to standardize study documentation in the social sciences has grown into a global collaboration supporting metadata description across diverse scientific domains.

Origins (1995-2002): Laying the Foundation

1995: The first SGML Codebook Committee meets in Quebec City. Constituted by ICPSR Director Richard Rockwell, the committee develops a draft list of codebook elements. This is the earliest framework for what would become the DDI standard.
1996: The first DDI specification is produced as an SGML Document Type Definition (DTD). It is developed by David Barber and John Brandt (University of Michigan), Ann Green (Yale University), and members of the DDI Committee.
1997-2000: Funding from the U.S. National Science Foundation (NSF) (award SBR-9617813, Final Report (PDF)) supports development, beta testing, and broader refinement. During this period, Jan Nielsen of the Danish Data Archive translates the SGML DDI specification into XML. In 2000, the first official release of DDI Version 1 (DTD-based) is published.
2001: A formal NSF evaluation (PDF) reports that all "evaluators were in agreement that the DDI is a worthwhile scientific effort and that it fills an urgent need for standardization of social science technical documentation and interoperability." That same year, a working group on aggregate data meets in Voorburg and develops a proposal to extend DDI to support aggregate and tabular data. In addition, the first DDI training workshop, "Creating DDI Compliant Codebooks," is held at IASSIST in Amsterdam, led by Bill Block, Wendy Thomas, Robert Wozniak, and Joshua Buysse.
2002: Momentum grows toward institutionalizing DDI as a sustained international standard. Funding from Health Canada supports a series of meetings, including a committee meeting in Storrs, Connecticut, where participants draft the DDI Alliance Charter (archived copy).

Establishing the Alliance (2003-2008): From Standard to Organization

2003: The DDI Alliance is formally established, with Tom Piazza (UC-Berkeley) as its first Chair (view “About the Specification” from the original Alliance Web site, March 2007). The Alliance creates governance structures, including the original Bylaws, and begins guiding development of future versions. The DDI Alliance Steering Committee meets for the first time, and DDI Version 2 is published with expanded support for aggregate data and geography. (View the full DTD Version History.)
2003-2006: The DDI Expert Committee leads the development of what will become DDI Version 3. This work is shaped with extensive community consultation and introduces the concept of a full data lifecycle model, significantly broadening the scope of the standard. View the Minutes.
2007: Public reviews and training workshops play a key role in refining DDI 3, including the first DDI training workshop held at Schloss Dagstuhl.
2008: DDI Version 3.0 is published as XML Schemas. It supports complex datasets and represents a major evolution beyond the earlier codebook-centric approach. Alongside the specification, Best Practices documentation is also developed to support implementation.

Growth and Maturation (2009-2015): Community, Standards, & Collaboration

2009: DDI Lifecycle 3.1 is published. The first European DDI Users Conference (EDDI) is held in Bonn, Germany, establishing a regular forum for the DDI community (archived program (PDF)).
2010: The DDI Expert Committee rebrands DDI 2 and 3 as DDI-Codebook and DDI-Lifecycle.
2011: An external review (PDF) of DDI governance and intellectual property issues is conducted. The Alliance establishes an agency registry, launches a tools catalog, and publishes its first set of controlled vocabularies.
2012: DDI Codebook 2.5 is published as XML schemas. The Alliance formalizes plans for a model-based future for DDI (Dagstuhl paper (PDF)). Revisions to the DDI Alliance Bylaws lead to new elections for the Executive Board (formerly the Steering Committee), including its Chair and Vice Chair.
2013: RDF and XKOS vocabularies supporting discovery are released for public review. DDI “Sprints” are launched to advance model-based development. The first North American DDI Users Conference (NADDI) is held in Lawrence, Kansas (archived program). The first DDI Executive Board (the successor to the Steering Committee) meets.
2014: The DDI Alliance publishes its Strategic Plan, 2014-2017. DDI-Lifecycle Version 3.2 is published.
2015: The Alliance redesigns its website (archived copy), releases the first model-driven DDI development drafts, and hosts its first Dagstuhl workshop focused on interoperability with other metadata standards. Mary Vardigan retires as Executive Director, and Jared Lyle is appointed as her successor.

Modern Era (2016-2025): Interoperability & Strategic Impact

2016-2018: Model-based DDI (often referred to as Version 4) is developed and released. A Train-the-Trainer workshop is held to increase DDI training capacity.
2019-2020: XKOS (Extended Knowledge Organization System) and SDTL (Structured Data Transformation Language) are published. The Alliance signs a letter of collaboration with CODATA (Committee on Data of the International Science Council) and co-hosts a Dagstuhl workshop on cross-domain data standards for science, health, and social science (report (PDF)). DDI-Lifecycle 3.3 is publicly released. DDI-Cross Domain Integration (DDI-CDI), an application of the model emerging from DDI 4, enters public review. The DDI Bylaws are amended to improve the structure and organization of the Scientific Board.
2021-2023: Strategic and scientific work plans guide development and community engagement (Strategic Plan, 2021-2023; Scientific Work Plan, 2021-2022; Scientific Work Plan, 2023). The Alliance establishes a simple liaison relationship with the World ide Web Consortium (W3C) to coordinate work on data description and specification development. The reorganized and newly elected Scientific Board meets for the first time.
2024-2025: DDI Cross-Domain Integration (DDI-CDI) Version 1.0 is approved and published. New strategic and scientific plans (Strategic Plan, 2024-2027; Scientific Work Plan, 2024-2026) set priorities for broader adoption, interoperability, and sustainable development of DDI standards.

Expert Committee

2009: Expert Committee meets in Tampere. Committee discusses tools and outreach to NSIs. View the Minutes.
2006: Expert Committee meets in Ann Arbor Committee approves the scope and timeline for Version 3. View the Minutes.
2005: Expert Committee meets in Edinburgh Committee ratifies life cycle model and DDI 3 begins to take shape. View the Minutes.
2004: Expert Committee meets in Madison, WI Committee discusses requirements for Version 3. View the Minutes. View the Lifecycle Model.