The ESS questionnaire in the UK is fielded using CAPI. The supplementary questionnaire is fielded face-to-face as an extension to the main interview. The questionnaire is fielded in English. The questionnaire fielded is based on to the source questionnaire but country-specific information e.g. lists of political parties, religions, education system and partnership status have been included or adaptations have been made to reflect national context.
ESS samples are representative of all persons aged 15 and over (no upper age limit) resident within private households in the UK, regardless of their nationality, citizenship or language. Individuals are selected by strict random probability methods at every stage and a minimum ‘effective achieved sample size’ of 1,500 is aimed for after discounting for design effects.
The ESS sample design in the UK is a clustered, stratified, 3-stage random probability design and excludes the following areas: north of the Caledonian Canal, the Isle of Man and the Channel Islands. The sampling frame used is the Post Office Address File and is a sample of addresses.