To calculate this indicator, companies are identified with legal units, i.e. each legal unit forms a company, which may consist of one or more establishments.

At the national level, until 2017 companies are identified with the legal units, However, from 2018 onwards, the concept of a company established by the European Union Regulation (696/93) is used, according to which a company may be made up of one or more legal units, which may be made up of one or more establishments. It should be noted that most companies are independent legal units, so this change only affects legal units that are part of groups of companies. Consequently, since 2018 the regional data are not strictly comparable with the national data. In addition, the national data from 2018 onwards are not strictly comparable with those until 2017.

For the time period from 2010 to 2014, information was sourced from the Industrial Companies Survey of the National Statistics Institute (INE). It should be borne in mind that until 2012, the scope of the survey focused on companies with employees and did not take into account the autonomous cities of Ceuta and Melilla. However, since 2013, the survey's scope has included both companies without employees and the autonomous cities of Ceuta and Melilla.

Indicator 9.3.1