New features on SDMX 3.X will provide microdata support, this is useful for NSOs to gather information based on SDMX structures that can be used to validate the data during the work field. The problem is the following:
Statistical Variable is a concept used as a characteristic of the observed unit that may assume more than one of a set of values to which a numerical measure or a category from a classification can be assigned.
Accordingly to GSIM a Variable is a specialization of Concept.
In this regard, the Indicators that are now modeled in SDMX and grouped by mean of codelists take the place of Statistical Variables that are the subject of measure (the measure dimension), and the other Dimensions are Concepts that serve to categorize/filter the Variable (indicator).
When dealing with microdata all the Concepts are Measures (Observations) of the Observation Unit, but we haven't built a Statistical Variable yet (we don't have a Measure Dimension).
We need to review the technical specifications (and in special the information model) to:
Provide a key to identify each of the Observation Units. Actual Keys will not be enough because several information Units may have the same values for their Dimensions. The DimensionDescriptor doesn't fit this purpose as it refers to a Key composed of Dimensions.
For me it is not clear that we still have only two types of Dimensions: Dimension and TimeDimension (Besides geo is a role for a Geographic Dimension I'm not sure if this must be addressed as a different kind of Dimension; from my point of view, maybe we have to talk about four types of dimensions: Measure, Concept, Time, and Location). What we now call Measure can be kept as "Primary Measure" when talking about aggregates, but not for microdata.
Clarify that the Statistical Variables are the indicators (aggregated values) that we relate to the Measures (a role of Statistical Variable would be useful, something to be included in a COG)
State that many Concepts may have a role of Measures (indeed we don't have a primary measure) in some DSD that will deal with microdata and will take other roles for dissemination purposes (this may be something that fits better in a COG).
Additionally:
In the SDMX Glossary, Measure is defined as: "Data element that represents a simple aggregation and which takes one or more vectors as arguments and returns a scalar." This applies to aggregated data, but not to microdata. We will need to update this definition.
New features on SDMX 3.X will provide microdata support, this is useful for NSOs to gather information based on SDMX structures that can be used to validate the data during the work field. The problem is the following: