Changes for page Guidelines on coding time transformations in SDMX

Last modified by Artur K. on 2026/05/29 14:28

From 2.1 to 1.6 From 2.8 to 2.7

From version 2.7

edited by Helena K.
on 2026/01/27 13:41

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To version 2.1

edited by Helena K.
on 2026/01/27 13:35

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@@ -12,12 +12,12 @@
  Examples:
--|(% style="width:501px" %)**Statement**|(% style="width:303px" %)**T**|(% style="width:472px" %)**P**|(% style="width:454px" %)**F**
--|(% style="width:501px" %)Quarter on quarter growth rate|(% style="width:303px" %)Growth rate|(% style="width:472px" %)2|(% style="width:454px" %)Q
--|(% style="width:501px" %)Contribution to growth over 1 year (quarterly data)|(% style="width:303px" %)Contribution to growth|(% style="width:472px" %)4|(% style="width:454px" %)Q
--|(% style="width:501px" %)Contribution to growth over 1 year (annual data)|(% style="width:303px" %)Contribution to growth|(% style="width:472px" %)1|(% style="width:454px" %)A
--|(% style="width:501px" %)3 months moving average|(% style="width:303px" %)Moving average|(% style="width:472px" %)3|(% style="width:454px" %)M
--|(% style="width:501px" %)Annual index (reference year=100){{footnote}}Note that for the case of an index, it is useful to specify the reference base period in an additional attribute (see concept BASE_PER specified in the SDMX Glossary).{{/footnote}}|(% style="width:303px" %)Index|(% style="width:472px" %)1|(% style="width:454px" %)A
++|Statement|T|P|F
++|Quarter on quarter growth rate|Growth rate|2|Q
++|Contribution to growth over 1 year (quarterly data)|Contribution to growth|4|Q
++|Contribution to growth over 1 year (annual data)|Contribution to growth|1|A
++|3 months moving average|Moving average|3|M
++|Annual index (reference year=100)[[~[1~]>>path:#_ftn1]]|Index|1|A
  This guideline describes two methods that may be used to code a time transformation:
@@ -26,7 +26,7 @@
  Both of these methods are included as separate use cases as served by each method. The aim of this document is to demonstrate that guidance and a standard approach is available and promoted for each use case. The use cases are described in the related sections.
--Further recommended code values for expressing general statistical concepts such as "not applicable", etc., can be found in section “Generic codes” of the "Guidelines for the creation and management of SDMX Cross-Domain Code Lists" (to be found under “Guidelines” on the official SDMX website{{footnote}}http://sdmx.org/{{/footnote}}).
++Further recommended code values for expressing general statistical concepts such as "not applicable", etc., can be found in section “Generic codes” of the "Guidelines for the creation and management of SDMX Cross-Domain Code Lists" (to be found under “Guidelines” on the official SDMX website[[~[2~]>>path:#_ftn2]]).
  = 2. SDMX Concepts for Time Transformations =
@@ -37,26 +37,29 @@
  Definition: This concept provides coded information about time-related transformation types of time series.
  **Concept ID: **The concept ID is TIMETRANS_TYPE.
++
  **Code List Name**: Code list for Time Transformation Type.
++
  **Code List ID:** CL_TIMETRANS_TYPE.
++
  **Established international standard(s) used as input for the code list**: None.
  **Version**: 1.0, 15 September 2016
--|**Recommended code value**|(% style="width:309px" %)Recommended code description|(% style="width:1262px" %)Annotation
--|**N**|(% style="width:309px" %)Non transformed|(% style="width:1262px" %)TIMETRANS_PER is always 1, since a non-transformed number covers by definition a single period
--|**A**|(% style="width:309px" %)Average|(% style="width:1262px" %)Moving average, i.e. an operation that preserves the frequency of the series
--|**C**|(% style="width:309px" %)Cumulated sum|(% style="width:1262px" %)
--|**D**|(% style="width:309px" %)Difference|(% style="width:1262px" %)
--|**DD**|(% style="width:309px" %)Difference, second order|(% style="width:1262px" %)A second order difference is the delta of deltas
--|**F**|(% style="width:309px" %)Growth rate, flow over stock|(% style="width:1262px" %)
--|**FC**|(% style="width:309px" %)Contribution to growth, flow over stock|(% style="width:1262px" %)
--|**G**|(% style="width:309px" %)Growth rate|(% style="width:1262px" %)
--|**GC**|(% style="width:309px" %)Contribution to growth|(% style="width:1262px" %)
--|**I**|(% style="width:309px" %)Index|(% style="width:1262px" %)In the usual case, the index is fixed to 100 for a specific reference period, in most cases a year. It is recommended that the DSD contains an additional attribute BASE_PER (type ObservationalTimePeriod), which specifies the reference period of the index. In special cases (e.g. National Accounts chain linking), the index is fixed to a value different to 100 in the reference year. In these cases the BASE_PER attribute is even more important.
--|**LA**|(% style="width:309px" %)Annualised levels|(% style="width:1262px" %)This relates to stock versus flow series. For example, many countries publish their Quarterly National Accounts (QNA) at quarterly level, which means that annual Gross Domestic Product (GDP) is the sum of the four quarters, whereas some countries publish their QNA at annual level (e.g. US), which means that annual GDP is the average of the four quarters. In order to present quarterly data in comparable levels across countries and to derive zone aggregates, quarterly data expressed at quarterly levels are “transformed” to annual levels (i.e. multiplied by four) and have this code.
--|**S**|(% style="width:309px" %)Shifted|(% style="width:1262px" %)The time series was moved back or forth in time. This may for instance be used when non-calendar year series are aligned to the calendar year using certain estimation formulas.
--|**_O**|(% style="width:309px" %)Other transformation|(% style="width:1262px" %)This code is taken from the guidelines on generic codes, specifying "Other". In that context it should be used if more complex transformations are applied. An explanation of the transformation or a transformation script should be given in a comment field.
++|**Recommended code value**|Recommended code description|Annotation
++|**N**|Non transformed|TIMETRANS_PER is always 1, since a non-transformed number covers by definition a single period
++|**A**|Average|Moving average, i.e. an operation that preserves the frequency of the series
++|**C**|Cumulated sum|
++|**D**|Difference|
++|**DD**|Difference, second order|A second order difference is the delta of deltas
++|**F**|Growth rate, flow over stock|
++|**FC**|Contribution to growth, flow over stock|
++|**G**|Growth rate|
++|**GC**|Contribution to growth|
++|**I**|Index|In the usual case, the index is fixed to 100 for a specific reference period, in most cases a year. It is recommended that the DSD contains an additional attribute BASE_PER (type ObservationalTimePeriod), which specifies the reference period of the index. In special cases (e.g. National Accounts chain linking), the index is fixed to a value different to 100 in the reference year. In these cases the BASE_PER attribute is even more important.
++|**LA**|Annualised levels|This relates to stock versus flow series. For example, many countries publish their Quarterly National Accounts (QNA) at quarterly level, which means that annual Gross Domestic Product (GDP) is the sum of the four quarters, whereas some countries publish their QNA at annual level (e.g. US), which means that annual GDP is the average of the four quarters. In order to present quarterly data in comparable levels across countries and to derive zone aggregates, quarterly data expressed at quarterly levels are “transformed” to annual levels (i.e. multiplied by four) and have this code.
++|**S**|Shifted|The time series was moved back or forth in time. This may for instance be used when non-calendar year series are aligned to the calendar year using certain estimation formulas.
++|**_O**|Other transformation|This code is taken from the guidelines on generic codes, specifying "Other". In that context it should be used if more complex transformations are applied. An explanation of the transformation or a transformation script should be given in a comment field.
  == 2.2 Time Transformation Periods ==
@@ -63,30 +63,45 @@
  Definition: This concept provides information about the number of periods used for a time-related transformation of the time series.
  **Concept ID: **The concept ID is TIMETRANS_PER.
++
  **Code List Name**: Code list for Time Transformation Periods.
++
  **Code List ID:** CL_TIMETRANS_PER.
++
  **Established international standard(s) used as input for the code list**: None.
  **Version**: 1.0, 15 September 2016
--(% style="width:1172.96px" %)
--|(% style="width:320px" %)**Recommended code value**|(% style="width:408px" %)**Recommended
--code description**|(% style="width:442px" %)**Annotation**
--|(% style="width:320px" %)**1**|(% style="width:408px" %)One|(% style="width:442px" %)
--|(% style="width:320px" %)**2**|(% style="width:408px" %)Two|(% style="width:442px" %)
--|(% style="width:320px" %)**etc.**|(% style="width:408px" %)etc.|(% style="width:442px" %)
++|**Recommended code value**|**Recommended
++code description**|**Annotation**
++|**1**|One|
++|**2**|Two|
++|**etc.**|etc.|
  == 2.3 Relation of transformation coding to transformation rules ==
  Transformation can also be expressed with transformation rules using a syntax such as the Validation and Transformation Language (VTL). Following the transformation graph model behind VTL, the transformation coding suggested in this guideline can be seen complementary with using transformation rules in VTL. The idea is that a coded non-transformed time series is transformed using a VTL rule and the result is then coded again with transformation codes for further data exchange. This principle is shown in the graph below:
--[[image:1769510498202-796.png]]
++|(((
++Level series
++)))
++
++|(((
++Transformed series
++)))
++
++|(((
++Transformation rule
++
++(VTL)
++)))
++
  Using the two concepts as suggested above for coding the type of transformation applied and the number of periods covered will additionally ensure that the parameters used for the formula are directly used in the coding of the resulting series. Thus no complex mapping is needed. The transformation applied is linked to the transformation type concept and the number of periods used for the calculation is linked to the transformation periods concept.
  **Example:**
--The formula for a simple annual growth rate can be expressed as follows:{{footnote}}Note: often growth rates are expressed as percentage growth, in which case the value is multiplied with 100%. This is however not relevant for this guideline and is left out for simplicity.{{/footnote}}
++The formula for a simple annual growth rate can be expressed as follows:[[~[3~]>>path:#_ftn3]]
  //GT= VT-VT-PVT-P//[[image:file:///C:/Users/axyli/AppData/Local/Temp/msohtmlclip1/01/clip_image001.png]]
@@ -147,8 +147,7 @@
  In case the mixed frequencies or complex transformations as outlined above are needed in a simpler way and normalisation does not need to be strictly enforced, a composite code list CL_TIMETRANS may be created.
--The number of periods in the code follows the frequency of the series unless stated otherwise. Example: code G3Y refers to a three-year growth rate, irrespective of the series frequency. For complex transformations, the codes that would be used for the respective transformations can be concatenated and separated by an underscore{{footnote}}Example:
--G1_C4 Growth rate, period on period, over 4-period cumulated sum{{/footnote}}.
++The number of periods in the code follows the frequency of the series unless stated otherwise. Example: code G3Y refers to a three-year growth rate, irrespective of the series frequency. For complex transformations, the codes that would be used for the respective transformations can be concatenated and separated by an underscore[[~[4~]>>path:#_ftn4]].
  Example for composite CL_TIMETRANS:
@@ -208,7 +208,7 @@
  The table below shows coding example using all 3 options lined out above.
--|Statement|Normalised{{footnote}}For sake of readability the prefix TIMETRANS_ was not put in the table. The concepts are in fact called TIMETRANS_TYPE and TIMETRANS_PER.{{/footnote}}|Type+Period|Type+Period+Freq
++|Statement|Normalised[[(% class="wikiinternallink" %)**~[5~]**>>path:#_ftn5]]|Type+Period|Type+Period+Freq
  |Level series (non transformed data)|(((
  FREQ=A or Q or M …
@@ -304,4 +304,16 @@
  ----
--{{putFootnotes/}}
++[[~[1~]>>path:#_ftnref1]] Note that for the case of an index, it is useful to specify the reference base period in an additional attribute (see concept BASE_PER specified in the SDMX Glossary).
++
++[[~[2~]>>path:#_ftnref2]] [[http:~~/~~/sdmx.org/>>url:http://sdmx.org/]]
++
++[[~[3~]>>path:#_ftnref3]] Note: often growth rates are expressed as percentage growth, in which case the value is multiplied with 100%. This is however not relevant for this guideline and is left out for simplicity.
++
++[[~[4~]>>path:#_ftnref4]] Example:
++
++|**G1_C4**|Growth rate, period on period, over 4-period cumulated sum
++
++
++
++[[~[5~]>>path:#_ftnref5]] For sake of readability the prefix **TIMETRANS_ **was not put in the table. The concepts are in fact called **TIMETRANS_TYPE** and **TIMETRANS_PER**.

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