Backcasting manual : 2025 edition

In October 2022, the European Commission ('the Commission') updated the common statistical classification of economic activities in the European Union (NACE). This took place by means of Commission Delegated Regulation (EU) 2023/137 (the 'NACE Rev. 2.1 Delegated Act'), which established NACE Revision 2 Update 1 ('NACE Rev. 2.1'), thus updating NACE Revision 2 ('NACE Rev. 2') which has been applied to European statistics since 2008. The NACE Rev. 2 classification was established in Regulation (EC) No 1893/2006 ('the NACE regulation') which replaces the previous NACE version (NACE Rev. 1.1). The NACE regulation also empowers the Commission to update its Annex I (which contains the codes and headings of the NACE Rev. 2 categories) to take account of technological or economic developments or to align it with other economic and social classifications. The transition from NACE Rev. 2 to NACE Rev. 2.1 requires that national statistical institutes (NSIs) backcast existing statistical time series (i.e. that they re-express them in terms of NACE Rev. 2.1) applying the most appropriate methods. Backcasting is a statistical technique that can be applied to historical statistics reported according to a classification - preferably in in such a way that consistency is preserved - to render backwards predictions of the same statistics expressed in terms of a new version of the same classification. The length of the NACE Rev. 2.1 backcasting periods has been set out for a number of statistical domains in Commission Implementing Regulation (EU) 2024/1840 (the 'NACE Rev. 2.1 Implementing Act'): - for short-term business statistics, data will be backcast retrospectively until the 2021 reference period; - for global value chain statistics, data will be backcast retrospectively until the 2021-2023 reference period.