Matching industry classifications. A method for converting Nace Rev.2 to Nace Rev.1

In 2008, Eurostat updated the Statistical Classification of Economic Activities (NACE) from NACE Rev.1 to NACE Rev.2. Eurostat provided correspondence tables to facilitate conversion between the two coding system at the 4 digit level. However, due to multiple correspondences, there is a need for a more accurate conversion system. This work aims at providing a useful and reliable tool to quickly convert sectoral level data from NACE Rev.2 into NACE Rev.1 through a back-casting procedure. We have developed a conversion matrix where sectoral weights are built on firm level employment data drawn from the ASIA Istat database. The adoption of employment weights to convert sectoral level data requires us to make assumptions on the stability of the economic structure over time and on the comparability between different data sources. We test our conversion matrix on the Community Innovation Surveys (CIS), converting CIS6 (2006-2008) from NACE Rev.2 into NACE Rev.1. In matching CIS6 with previous years, we do not find evidence of structural breaks.