Vmurrell: /* Attribute Attachment Levels */

2023-09-12T15:57:25Z

‎Attribute Attachment Levels

Vmurrell: /* Data Structure Components */

2023-09-12T15:56:13Z

‎Data Structure Components

Vmurrell: Created page with "Category:SDMX Structures =Overview=
An SDMX Data Structure Definition (DSD) provides a template which describes the dimensionality of related datasets in terms of their..."

2023-09-12T15:54:34Z

Created page with "Category:SDMX Structures =Overview= An SDMX Data Structure Definition (DSD) provides a template which describes the dimensionality of related datasets in terms of their..."

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[[Category:SDMX Structures]]
=Overview=
An SDMX Data Structure Definition (DSD) provides a template which describes the dimensionality of related datasets in terms of their dimensions, attributes and measures.

==Structure Properties==
{| class="wikitable"
! scope=row style="text-align: left;" | Structure Type
| Standard SDMX Structural Metadata Artefact
|-
! scope=row style="text-align: left;" | Maintainable
| [[Maintainable V11|Yes]]
|-
! scope=row style="text-align: left;" | Identifiable
| [[Identifiable V11|Yes]]
|-
! scope=row style="text-align: left;" | Item Scheme
| [[Item_Scheme V11|No]]
|-
! scope=row style="text-align: left;" | SDMX Information Model Versions
| 1.0, 2.0, 2.1, 3.0
|-
! scope=row style="text-align: left;" | URN - DataStructure namespace
| <nowiki>urn:sdmx:org.sdmx.infomodel.datastructure.DataStructure</nowiki>
|-
! scope=row style="text-align: left;" | URN - Dimension namespace
| <nowiki>urn:sdmx:org.sdmx.infomodel.datastructure.Dimension</nowiki>
|-
! scope=row style="text-align: left;" | URN - Attribute namespace
| <nowiki>urn:sdmx:org.sdmx.infomodel.datastructure.DataAttribute</nowiki>
|-
! scope=row style="text-align: left;" | URN - MeasureDimension namespace
| <nowiki>urn:sdmx:org.sdmx.infomodel.datastructure.MeasureDimension</nowiki>
|-
! scope=row style="text-align: left;" | URN - TimeDimension namespace
| <nowiki>urn:sdmx:org.sdmx.infomodel.datastructure.TimeDimension</nowiki>
|-
|}

==Context within the SDMX 3.0 Information Model==

[[File:SDMX3 Data-or-MetadataStructureDefinition.png|Data or Metadata Structure Definition|600px]]

==Usage==
Data Structure Definitions (DSDs) are used to describe the structure of datasets by specifying their constituent [[Component|Components]]:
* [[Dimension|Dimensions]]
* [[Attribute|Attributes]]
* Measures
and optionally the [[Representation]] for each Component.

Each [[Data_or_Metadataflow|Dataflow]] references a single DSD which describes the structure of the dataset that the Dataflow represents.

=Conventions=

DSD IDs 
DSD IDs are conventionally uppercase using underscores '_' as separators if required. Examples: 
{| class="wikitable"
|-
! Agency !! DSD ID !! Description !! SDMX-ML
|-
| Eurostat || NA_MAIN || European National Accounts Main Aggregated Statistical Indicators || [https://registry.sdmx.org/ws/public/sdmxapi/rest/datastructure/ESTAT/NA_MAIN/1.11 SDMX-ML]
|-
| IMF || BPO || Balance of Payments and International Investment Position || [https://registry.sdmx.org/ws/public/sdmxapi/rest/datastructure/IMF/BOP/1.13 SDMX-ML]
|-
| IMF || ALT_FISCAL_DSD || Alternate Fiscal Data Structure Definition || [https://sdmxcentral.imf.org/ws/public/sdmxapi/rest/datastructure/IMF/ALT_FISCAL_DSD/1.0 SDMX-ML]
|-
| World Bank || WDI || World Development Indicators || [https://demo.metadatatechnology.com/FusionRegistry/ws/public/sdmxapi/rest/datastructure/WB/WDI/1.0 SDMX-ML]
|}
The SDMX standard does not preclude using lowercase or mixed case for structure IDs. However IDs are case sensitive meaning that a DSD with ID 'NATIONAL_ACCOUNTS' is distinct from another named 'National_Accounts'. 
TIME_PERIOD 
For Time Series DSDs, the [[Time Dimension]] Component is conventionally given the ID 'TIME_PERIOD'.


=Data Structure Components=

The role of Concepts In defining a DSD's Components 
Every Dimension, Attribute and Measure is described by a predefined [[Concepts V11|Concept]]. Concepts have their own default [[Representation]] which can be overridden by defining a Local Representation for the Component in the DSD. That's particularly helpful when using some standard Concepts like the [https://registry.sdmx.org/ws/public/sdmxapi/rest/conceptscheme/SDMX/CROSS_DOMAIN_CONCEPTS/2.0 SDMX Cross Domain Concepts] where the default Representation is 'String', but the Component needs to be Enumerated or have some use case specific restriction on what values are allowable.



Dimensions 
A DSDs Dimensions are the minimal set of statistical concepts capable of uniquely identifying a specific series. For [[Time Series]], the Dimensions in combination with the Time Dimension, uniquely identify an Observation. 
In this sense, the Dimensions of a dataset together form its primary key.



Ordering of Dimensions in a DSD 
The Dimensions in a DSD have a defined order and together form the dataset's [[Series Key]]. 
Below is a simple example DSD: 
{| class="wikitable"
|-
! Position !! Component Type !! Component ID !! Description
|-
| 1 || Dimension || INDICATOR || Indicator
|-
| 2 || Dimension || REF_AREA || Reference Area
|-
| 3 || Dimension || FREQUENCY || Data Frequency
|-
| n/a || Time Dimension || TIME_PERIOD || Observation Time
|-
| n/a || Attribute || UNIT_MULT || Unit Multiplier e.g. tens, thousands, millions
|-
| n/a || Attribute || Observation Status || Observation Status e.g. Estimated, Final
|-
| n/a || Primary Measure || Observation Value || The observation value
|}
The Series Key is the dot (.) concatenation of the Dimensions in the order specified in the DSD.

For the DSD above, the Series Key is constructed as follows:

'''<INDICATOR>.<REF_AREA>.<FREQUENCY>'''

Examples
ATMCO2.GRC.A
ATMCO2.GRC.M
TBSINDC.MDG.A
TBSINDC.GBR.M

Attributes do not form part of the Series Key so have no explicit or implied ordering.



Attributes 
Attributes allow extra concepts to be added to the dataset to provide additional information about the variable being measured such as the unit multiplier or observation status. 
Attributes are unique in that they must be attached to [[#Attribute Attachment Levels|specific levels in the dataset]] at DSD design time.



Primary Measure 
All DSDs must have a Primary Measure Component, which is used for the observation value of the main variable being measured. Like all components, the Primary Measure must reference a Concept. For many series, the measure is numeric, but does not need to be so.



Time Dimension 
A Time Dimension is required for DSDs representing [[Time Series]] datasets. Again, the Time Dimension must reference a Concept which should have an appropriate time representation - typically Observational Time Period.


=Attribute Attachment Levels=

In designing a DSD, attributes must be attached to specific levels in the dataset.
{| class="wikitable"
|-
! Attachment Level !! Description
|-
| Dataset || A single value for the attribute is set for the complete dataset
|-
| Series || A different value for the attribute can be set for each series
|-
| Observation || A different value for the attribute can be set for each individual observation in a time series
|-
| Group || A different value for the attribute can be set for a [[Group]] of series
|}
Example 'Demography' DSD with Attributes attached at the Series and Observation level: 
[[File:DSD With Attribute Attachments.PNG|500px]]


=Time Series=

DSDs for Time Series are characterised by having an explicit [[Time Dimension]]. 
In combination with the DSD's other Dimensions, the Time Dimension uniquely identifies an individual Observation within a Dataset.


=Non Time Series=

DSDs can be designed for non Time Series datasets by excluding the [[Time Dimension]]. This supports use cases like census statistics which, although the observations are from a fixed point in time, there's no sequence of observations over a period of time.


=Data Structure Definitions with Multiple Measures=
Data Structures can be created in the Registry containing multiple measures, however the generate data set option does not support multiple measures. FXL does not support Creating datasets with multiple measures.

@@ Line 150: / Line 150: @@
 | Observation || A different value for the attribute can be set for each individual observation in a time series
 |-
-| Group || A different value for the attribute can be set for a [[Group]] of series
+| Group || A different value for the attribute can be set for a Group of series
 |}
 Example 'Demography' DSD with Attributes attached at the Series and Observation level:<br><br>

@@ Line 74: / Line 74: @@
 <p>
 <strong>The role of Concepts In defining a DSD's Components</strong><br>
-Every Dimension, Attribute and Measure is described by a predefined [[Concepts V11|Concept]]. Concepts have their own default [[Representation]] which can be overridden by defining a Local Representation for the Component in the DSD. That's particularly helpful when using some standard Concepts like the [https://registry.sdmx.org/ws/public/sdmxapi/rest/conceptscheme/SDMX/CROSS_DOMAIN_CONCEPTS/2.0 SDMX Cross Domain Concepts] where the default Representation is 'String', but the Component needs to be Enumerated or have some use case specific restriction on what values are allowable.
+Every Dimension, Attribute and Measure is described by a predefined [[Concepts|Concept]]. Concepts have their own default [[Representation]] which can be overridden by defining a Local Representation for the Component in the DSD. That's particularly helpful when using some standard Concepts like the [https://registry.sdmx.org/ws/public/sdmxapi/rest/conceptscheme/SDMX/CROSS_DOMAIN_CONCEPTS/2.0 SDMX Cross Domain Concepts] where the default Representation is 'String', but the Component needs to be Enumerated or have some use case specific restriction on what values are allowable.
 </p>

Data or Metadata Structure Definition - Revision history

Vmurrell: /* Attribute Attachment Levels */

Vmurrell: /* Data Structure Components */

Vmurrell: Created page with "Category:SDMX Structures =Overview= An SDMX Data Structure Definition (DSD) provides a template which describes the dimensionality of related datasets in terms of their..."

Vmurrell: Created page with "Category:SDMX Structures =Overview=
An SDMX Data Structure Definition (DSD) provides a template which describes the dimensionality of related datasets in terms of their..."