The English Longitudinal Study of Ageing (ELSA) is a unique and rich resource of information on the dynamics of health, social, wellbeing and economic circumstances in the English population aged 50 and older.
Established in 2002, the original sample was drawn from households that had previously responded to the Health Survey for England (HSE) between 1998 and 2001. The same group of respondents have been interviewed at two-yearly interviews, known as ‘waves’, to measure changes in their health, economic and social circumstances. Younger age groups are replaced or refreshed to retain the panel. The sample has been refreshed using HSE participants in waves 3, 4, 6, 7 and 9.
Although new topics can be introduced at different waves, every module has been reviewed to ensure that it will provide data that can measure change over time. This is achieved by repeating some measures exactly, by asking directly about change, and by adopting questions to allow people to update or amend past responses.
The information collected provides data about:
Household and individual demographics
Health – physical and psychosocial
Social care (from Wave 6)
Work and pensions
Income and assets
Effort and Reward (voluntary work and caring)
In addition, certain waves contain one-off modules and questions.
The ELSA sample has been designed to represent people aged 50 and over, living in private households in England. The sample is based on respondents who participated in the Health Survey for England (HSE). The original sample was selected from three years of HSE: 1998, 1999 and 2001. These years were chosen because they were recent and could provide a sufficiently large sample size. ELSA used the core samples for these years, all of which were nationally representative.
The HSE 1999 sample design also included a boost sample that represented ethnic minorities. Because of funding constraints, it was not possible to follow-up the boost sample and it was discarded. Together these three HSE years contained 23,132 responding households.
Households were removed from the HSE sampling frame for ELSA Wave 1 if it was known that there was no adult of 50 years or older in the household who had agreed to be re-contacted at some time in the future. Individuals in the remaining households provided the basis for the ELSA Wave 1 sample (11,578 households containing 18,813 eligible individuals).
The Wave 1 original sample was drawn from HSE respondents aged 50+ on the 1st March 2002. As ELSA is a study of those aged 50+, it needs to be periodically refreshed with additional sample members aged from 50. Subsequent refreshment samples were drawn from other HSE years with differing age criteria to correct the age profile of the resulting cohort.
The ELSA sample has been refreshed several times now, at waves 3, 4, 6, 7 and 9. When a refreshment sample is drawn, households from HSE are selected for ELSA if at least one HSE interview was conducted with an age eligible respondent who agreed to be re-contacted. Each refreshment sample added then becomes part of the cohort issued again at subsequent waves.
To enable longitudinal analysis, the same key topics are included in the content of the questionnaire for each wave, while others may be rotated on and off.
The nurse interview involves measurements of physical function, anthropometric measurements and collection of blood samples (for extraction of biomarkers and DNA). To view which basic topics are asked at individual waves please click here.