Group Occupations and Underlying Roles have been standardised using The National Statistics European Socio-economic Classification (NS-SEC). These have been constructed to measure the employment relations and conditions of occupations. Conceptually, these are central to showing the structure of socio-economic positions in modern societies and helping to explain variations in social behaviour and other social phenomena.

The NS-SEC is an occupationally based classification allowing Group Occupations and Underlying Roles to be standardised but rules have been provided to ensure coverage of the whole adult population. The information required to create the NS-SEC is occupation coded to the unit groups (OUG) and details of employment status: whether an employer, self-employed or employee; whether a supervisor; and the number of employees at a workplace. These classifications are used extensively across government and feature heavily in the census.