The BHPS is an annual survey consisting of a nationally representative sample of about 5,500 households recruited in 1991, containing a total of approximately 10,000 interviewed individuals. The sample is a stratified clustered design drawn from the Postcode Address File and all residents present at those addresses at the first wave of the survey were designated as panel members. These same individuals are re-interviewed each successive year and, if they split-off from original households to form new households, they are followed and all adult members of these households are also interviewed. Similarly, new members joining sample households become eligible for interview and children are interviewed as they reach the age of 16. Since 1994, children aged 11-15 also complete a short interview.
Extension samples of 1,500 households in each of Scotland and Wales were added to the main BHPS sample in 1999 to enable independent analysis of each country. In 2001 a sample of 2,000 households was added in Northern Ireland. The total sample size for the BHPS including the extension samples is now around 10,000 households across the UK. The extension samples allow for country specific and comparative research within the UK.
Further details about all aspects of the BHPS design, sample, fieldwork operation and data processing procedures are available in the most recent BHPS quality profile (PDF) and in the User Documentation.