munging metadata

When people point to flaws in SDTM, they typically appear to me as gaps in the existing standard. In general, CDISC started defining standards by focusing on the basic structural metadata (e.g. domains, variables, code lists). This makes sense because this structural metadata is fundamentally useful, and relatively easy to understand and create. As the industry’s use of the standards has increased, so has the demand for standards that can be implemented more consistently and easily, as well as standards that are more computable. The limitations in the current standards are gaps, and addressing these gaps represents a natural evolution for the CDISC standards. As noted in my previous post “What’s in a SHARE Value Level Metadata Library?” CDISC does not currently contain Value Level Metadata (VLM) content, and this content represents a lot of new metadata. VLM is a gap in the existing standards. How do we know what variables are impacted by a specific –TESTCD? Much of that informati...

What’s in a Value Level Metadata (VLM) Library? SHARE has the capability to store and publish Value Level Metadata (VLM) content. Currently, the only CDISC standard describing VLM is Define-XML. Define-XML provides the structure for VLM along with some guidelines on when it’s useful, but it does not provide standard VLM content. The Define-XML v2.0 specification states that VLM should be applied when it provides information useful for interpreting study data, and that it need not be applied in all cases. Precisely what and where VLM should be used is determined by study implementers. Since there are no hard and fast rules describing when to use VLM, what should be included in a SHARE library of VLM content? It might be useful to ask, “where is VLM being used today?” Based on input so far, most implementers add VLM where they think the regulatory reviewers might want to see it. Since many organizations are not yet using Define-XML as a machine-readable specification, but are inst...

During May and June the SHARE team has been busy on a number of fronts. In June we plan to begin beta testing the eSHARE site for machine-readable downloads of the CDISC standards.  The eSHARE site will be part of the new CDISC web site that will be launched in June. The SHARE team has also been actively designing new forms of standards content for SHARE, including Research Concepts and explicit Value Level Metadata representations. A white paper describing our initial solution for Research Concepts will be distributed for review in June. Also during June we plan to complete an initial proof-of-concept project towards a long-term Research Concept solution. Value Level Metadata (VLM) blog postings started in May and will continue through June. We plan to publish a white paper describing how VLM content will be represented in SHARE, and exported in Define-XML format, later in the summer. The SHARE Metadata Curators continue their work with the foundational standards teams to lo...

As part of the work to implement Value Level Metadata in SHARE, as well as to author a Define-XML Implementation Guide article, this will be the first of a series of posts on the topic of Value Level Metadata. These posts target a more technical audience, however the Define-XML IG article will include less technical jargon. Future posts will cover additional Value Level Metadata topics and examples. Value Level Metadata (VLM) is metadata that constrains a variable definition based on the value of another variable(s). VLM was originally specified in Define-XML v1.0 as a mechanism for providing the additional metadata needed for software to more accurately interpret these constrained variables.  For example, VSORRES is a variable with structural metadata of  DataType=”Text” and Length=”200”. However, when VSTESTCD=”DIABP” that definition is constrained by VLM to use DataType=”integer” and Length="3". In this case, the value of DIABP in VSTESTCD has triggered the application o...