Controlled VocabulariesΒΆ

There are many points in the DDI where a controlled vocabulary is desired, but no single classification can be (or has been) identified which would be acceptable to all user communities. DDI-L provides a CodeValueType that allows for use of a simple descriptive term while also supporting the use of an externally described controlled vocabulary. A set of fields has been made available for identifying the following information about the controlled vocabulary including; the name or identifier, maintenance agency, version, and URL of the controlled vocabulary. DDI is supporting the option of developing and publishing controlled vocabularies expressed in a DDI profile of Genericode. These may be used directly or incorporated into local publications of controlled vocabularies that reflect those elements that are common with the DDI community and adding those that are specific to the the maintenance agency.

This approach supports sharing of common coding structures as well as the publication of code schemes in formats that can be mapped for comparability. DDI publishes a set of controlled vocabularies commonly used in social science research (http://www.ddialliance.org/controlled-vocabularies). These are presented in a variety of formats including Genericode XML.