5. Transition from reference year 2010=100 to 2015=100

The tables for the 2010=100 series were discontinued on the publication of the January 2020 figures for the new 2015=100 series. Up-to-date figures can be found in the 2015=100 series.
For civil engineering as a whole and the individual areas, the new 2015=100 series can be linked to the old 2010=100 series if required. A recommendation is provided below on the method for switching from the old to the new series. If you wish to use the results of the civil engineering price indices for indexation, you have a number of options:

• The calculation of a price development over a period starting in or after January 2008 and ending in October 2019 at the latest is based on the 2010=100 series.
• The calculation of a price development over a period starting in or after January 2012 and ending after October 2019 is based on the 2015=100 series.

• The calculation of a price development over a period starting between January 2008 and the end of October 2011 and ending after October 2019 is based on an index-linked 2010=100 series. From January 2020, in the 2015=100 series, the percentage development relative to October 2018 must be calculated, because the price index for October 2018 was the last final figure published on the 2010=100 basis; thereafter this development must be ‘switched to’ the October 2018 results of the 2010=100 series (see table 2).
  
  

  2. Linking example

  Period	Index 2010=100	Index 2015=100	Index linked series
  October 2018	114.5	112.1	114.5
  January 2020		114.2	116.6

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  The January index of the linked series is established by determining the development between October 2018 and January 2020 according to the 2015=100 series and multiplying it by the October 2018 index from the 2010=100 series. In the example: (114.2/112.1) * 114.5 = 116.6 (rounded). For April 2020 the index is calculated according to the same line, in each case with a link in October 2018.

These linking recommendations are based on two principles: (1) the price developments are calculated as far as possible within a single published series and (2) retroactive adjustments and corrections must be avoided as far as possible.
In addition to the series with different base years describing a limited period, CBS also publishes a historical 2000=100 series, from 1979. In this historical series, the series are linked together from the first publication period.
If you have any questions or difficulties, please contact the CBS information service.