Free the concepts!

Variables and concepts are at the center of the DDI Lifecycle model. Variables are key to describe the data in its different states. Concepts help understanding the meaning of the data and its links to information in the outside world; concepts are also pivotal for implementing FAIR principles, specifically the knowledge representation and vocabulary principles for interoperability.Nevertheless, the practical implementation in Lifecycle of the variable / concept duo is hampered by a strict zero to one relation: a variable may have a reference to at most one concept! In our experience, we found this a very hard limit that we are trying to lift.This presentation will: describe a case study: when documenting variables from the data collection of a health cohort, we find that most of these variable labels refer to several concepts that need to be represented; list possible solutions with the standard as it is - by leveraging existing elements or attributes like IncludesConceptReference - or using other standards (like SKOS or I-ADOPT) and also consider evolutions of the standard, including of course relaxing the 0 to 1 constraint. Finally, we will discuss how to continue this conversation with DDI users and maintainers.