Effects of a sequential mixed-mode design on participation, contact and sample composition – Results of the pilot study “IMOA – Improving Health Monitoring in Old Age”
Existing health survey data of individuals who are 65+ years of age is limited due to the exclusion of the oldest old and physically or cognitively impaired individuals. This study aimed to assess the effects of a sequential mixed-mode design on (1) contact and response rates, (2) sample composition and (3) non-response bias. A register-based random sample of 2,000 individuals 65+ years was initially contacted by mail to answer a health questionnaire. Random subgroups of initial non-responders were further contacted by telephone or home visits. Participation by interview or proxy was possible. After postal contact only, the initial contact and …
