One central dimension in exploring the potential and limitations of quantitative ageing research is the quality of existing survey data. Using the German Ageing Survey (DEAS), we will put forward findings for the interrelation of age and several methodological issues.
DEAS is a nationwide representative cross-sectional and longitudinal survey of the German population aged over 40 and had started in 1996. Participants are questioned in detail on their objective and subjective living situation. Also, tests of cognitive capability and physical functioning are applied. Information is gathered via a CAPI and a self-administered PAPI and CAWI (since 2017) questionnaire.
We will concentrate on two main issues: First, we will present findings on whether and how age correlates with attrition, non-response, tendencies for acquiescence or satisficing, as well as cognitive abilities and the factoral structure of several psychological instruments and scales.
Second, we analyse the longitudinal accuracy and plausibility of retrospective biographical information: in each survey year, respondents are asked for their fertility biography (the number of children they have born, in which year they were born, and whether these are still alive). This repeated recording allows to compare deviations in the recollection of major biographic events and to analyse whether intra-personal inconsistency rises with age.
We will conclude with an evaluation of data quality in older (DEAS) respondents and provide some practical suggestions for survey designers and data users in quantitative ageing research.