Non-response in surveys of very old people.

Very old people are known to participate less often in social surveys than younger age-groups. However, survey participation among very old people in institutional settings is understudied. Additionally, the focus of the literature is on response rates, which neglects the complexity of the process of survey participation. The present study uses standard definitions of the American Association for Public Opinion Research to give a detailed description of survey participation among very old people, including those in institutional settings. Data come from a German survey on quality of life and subjective well-being of persons aged 80-84, 85-89, and 90+ (N = 1800). The present study (a) estimates contact, cooperation, response, and refusal rates and (b) identifies associations of age, sex, and type of residence with each of these rates. Weighted outcome rates for the survey were: contact = 66.0%, cooperation = 39.6%, response = 26.1%, and refusal = 26.9%. Age, sex, and type of residence were not associated with the contact, cooperation, and response rate. Lower refusal rates were found for people aged 90+, men, and institutionalized people. Additional analyses showed higher rates of non-interviews due to health-related reasons for institutionalized people and those aged 90+. Overall, results indicate that institutionalized and non-institutionalized people showed similar levels of survey participation. Willingness to participate is a key factor for women and people in private households, while the ability to participate is more important for institutionalized people.