The socio-economic group was assigned to each person depending on their current or previous paid occupation (people who have had paid work at some point in their lives). People that have never had an occupation of this kind are placed in the socio-economic group which corresponds to the person on whom they depend financially (partners, fathers, mothers, etc.). Each person is assigned to each of the five groups by means of a three-digit code number from the National Classification of Occupations which came into force in 2011 (CNO-11) proposed by the Determinants Working Group of the Spanish Society of Epidemiology (SEE).

Grouped classification II. (5 categories)

1. Directors and general managers of establishments with 10 or more salaried employees and professionals traditionally associated with university degrees.
2. Directors and general managers of establishments with fewer than 10 employees, professionals traditionally associated with university diplomas and other technical support professionals. Sportspeople and artists.
3. Intermediate occupations and self-employed workers.
4. Supervisors and skilled and semi-skilled workers in technical occupations.
5. Unskilled workers.