The sample gives insight into the radio-listening habits of the permanent, linguistically assimilated population of Switzerland aged 15 and above. Permanently domiciled persons include Swiss citizens, foreign nationals with annual residency or settlement permits (B and C permits) as well as international civil servants (FDFA permit) with a basic knowledge of one of the native languages. Short-term residents and cross-border commuters are not included in the study. The universe comprises members of private and collective households.

Population covered in all of Switzerland in 2011: 6.5 million persons.

The size and structure of the studied universe are adjusted annually to reflect actual population figures using updated census data provided by the Federal Office for Statistics (ESPOP).