The National Survey for Wales 2023-24 onwards

The survey will cover a representative, random sample of all people aged 16 or over (no upper age limit) resident within private households in Wales. The address sample will be a single-stage sample across Wales. Within each sampled household, where there are two or more eligible individuals the interviewer will select the respondent using a random selection technique. Approximately 12,000 interviews should be achieved in each financial year, unclustered across the year. The sample should be sufficiently representative within quarters to support national estimates based on each quarter.

The survey will provide results each year primarily at national, regional and local health board level, but will also support estimates at local authority level. The achieved sample size will be broadly proportionate to population size in each local authority, with over-sampling to achieve an effective sample size of approximately 750 respondents a year in Powys and 250 a year in the smallest authorities.

A modular questionnaire will be administered to each participating respondent. The questionnaire will be updated each year. The questionnaire will take 40 minutes to complete (median average across respondents). The survey will be carried out primarily by telephone, with a face-to-face, in-home interview for respondents who do not provide a phone number. In some years there will also be a 10-15 minute self-completion section within the overall 40 minute survey length, either online (for respondents who complete the first section by telephone) or by Computer-Assisted Self-Interview (CASI; for respondents completing the first section face-to-face).

Filtering and random subsampling of modules will be used to collect data only to the necessary level of precision for each topic. This means that for example where estimates are only needed at national level, a random subsample will be selected from the whole sample such that 2,000 respondents answer the relevant questions. The questionnaires supplied by the Client will be converted by the successful Bidder into computer scripts for fieldwork. Conversion of the materials will include detailed testing of the script by the successful Bidder.