DDI Moving Forward Process Summary

Full documentation on the DDI Moving Forward Project can be found on the DDI Collaboration Wiki


The next-generation version of the DDI specification will be based on an information model. This is a common strategy for standards development and it offers several benefits: improved communication with other disciplines and standards efforts, flexibility in terms of technical expressions of the model, and streamlined development and maintenance, among others.

The time is right for moving in this direction. Maintenance challenges related to the DDI-L structure have shown that continued improvement of the development line is limited by the lack of a data model. Further, we are experiencing pressure for changes from several directions at once. We need to integrate new content from substantive working groups, which requires new approaches to the design of the specification. We are also being asked to interact with other standards such as GSIM and SDMX as well as standards for metadata in other domains.

Goals for the new model-based specification include:

  • Extend data life cycle coverage
  • Broaden the focus to new research domains
  • Develop a robust and persistent conceptual model, with extension possibilities and  implementations in different technologies
  • Make the specification simpler and easier to understand and use, with better documentation

DDI of the future will include support for process and workflow, sampling frames, weighting, qualitative data, data access and analysis, data quality, disclosure risk review, and more. In addition, we plan a focus on abstraction of data capture/collection in order to describe data collected with instruments other than surveys.

Developing the DDI model is one of the strategic priorities of the DDI Alliance. The Alliance began work on a model-based DDI in October 2012 in a workshop at Schloss Dagstuhl – Leibniz Institute for Informatics, Wadern, Germany. A paper describing the discussions that took place during the workshop as well as model design goals and technical approaches is available.

More information on the Moving Forward process of DDI 4 development is available. The work on DDI 4 has progressed through a series of “sprints” to focus intensively on task completion and make good progress. User stories covering common use cases for DDI also feed into the process. The approach is based on the process used for the successful development of the Generic Statistical Information Model (GSIM), a project of several national statistical institutes to standardize the production of official statistics. Development of the model will be iterative with small pieces released, tested, and refined in a feedback loop.