Concept Scheme V11
A concept scheme is a container for Concepts which are reusable definitions for statistical items such as frequency, currency, and reference area (country).
Concepts may be referenced by multiple structures in SDMX, and therefore provide re-usable mechanism for giving meaning to structures.
A Data Structure Definition (DSD) provides a good example of how Concepts are used as to create a DSD. When defining a Data Structure Definition, each Dimension, Attribute and Measure is given a specific Concept. The dimensions etc. do not have names or descriptions, instead they provide a reference to a Concept which gives this information. To get a human readable name for a Dimension, the referenced Concept must first be obtained.
|Structure Type||Standard SDMX Structural Metadata Artefact|
|SDMX Information Model Versions||1.0, 2.0, 2.1, 3.0|
|URN - ConceptScheme namespace||urn:sdmx:org.sdmx.infomodel.conceptscheme.ConceptScheme|
|URN - concept namespace||urn:sdmx:org.sdmx.infomodel.conceptscheme.Concept|
Context within the SDMX 3.0 Information Model
Concepts are used by Dimensions, Attributes, Measures, and Metadata Attributes to provide them with a semantic meaning. Concepts can also be used to define a default representation, for example it is possible to link the Concept of Frequency to a Codelist containing all the Frequency Codes, and any structure using the Concept will inherit the default representation.
The SDMX Cross Domain Concept Scheme provides a range of standardised Concepts maintained by the SDMX Statistical Working Group (SWG) and can be viewed on the Global Registry site https://registry.sdmx.org/items/conceptscheme.html.
Concept Scheme IDs IDs are conventionally uppercase using underscores '_' as separators if required. Examples:
|Agency||Concept Scheme ID||Description||SDMX-ML|
|ESTAT||CS_NA||ESA 2010 - Transmission programme||SDMX-ML|
|SDMX||CROSS_DOMAIN_CONCEPTS||SDMX Cross Domain Concept Scheme|||
Flat Concept Schemes
Flat Concept Schemes are simple lists of codes with no explicit or implied relationships or hierarchies.
Example: SDMX Cross Domain Concept Scheme
|Code ID||Code Name||Description|
|ACC_CONV||Accounting conventions||Practical procedures, standards and other aspects used when compiling data from diverse so...|
|ACCURACY||Accuracy||Closeness of computations or estimates to the unknown exact or true values that the statistics w...|
|ACTION_TYPE||Action type||Behaviour to be undertaken by a system processing the information contained in a SDMX mess...|
|AGE||Age||Length of time that an entity has lived or existed.|
|CIVIL_STATUS||Civil status||Legal, conjugal status of each individual in relation to the marriage laws or customs of the countr...|
Concept Schemes with Simple Hierarchies
SDMX allows simple hierarchies to be defined within flat Concept Schemes by making a code the parent of codes that logically sit under it in the hierarchy.
Imagine a Concept Scheme including a Concept 'CONTACT' containing individual codes for details such as Name, Address, and Email etc. A simple hierarchy for CONTACT can be created by setting CONTACT as the parent for each of the Contact detail codes:
|Code ID||Code Name||Parent|
|CONTACT_EMAIL||Contact email address||CONTACT|
|CONTACT_PHONE||Contact phone number||CONTACT|
|CONTACT_MAIL||Contact mail address||CONTACT|
Other than acting as a parent, CONTACT behaves as a normal code allowing series for CONTACT or any of the individual details.
A Code can only have one parent meaning that it can only appear once in a simple Concept Scheme hierarchy.