Sampling design

The project of the Belgian Ageing Studies collects information from people aged 60 and over, living at home. Older people who live in institutional services are excluded from the research. Consequently, the samples in the Belgian Ageing Studies consist only of home-dwelling older citizens.

The municipalities were not randomly selected. Each municipality itself decides whether to participate in the research project or not. In each of the participating municipalities, the local government draws a random sample from the population register of the municipal inhabitants, applying stratified quota where the proportion of features such as gender and age (60 to 69, 70 to 79 and 80 years and over) are identical to in the underlying population. One of the assets of this kind of sampling is the assurance of the proportional presence of the most vulnerable age group (80+). In order to reduce the potential bias of non-response, volunteers received replacement addresses in the same quota category to exchange for respondents who refused or were hampered in filling-in the questionnaire.

The sampling fraction depends on the size of the municipality, and varies between N=182 and N=1592.

Consequently, the global dataset was not representative at a national level, but every sample was representative for the specific municipality.

 In total 64737 older people, living in 140 different Flemish and Walloon cities and towns participated.