Categorization of target groups
The Danish Civil Registration System was used to retrieve information on sex, age, ethnic background, and marital status. This information was used to categorize sample members in four separate subsamples; (1) sample members with non-western background and a non-Danish citizenship, (2) men aged 16–24 years, (3) women aged 75 years or older and (4) the remaining sample members. The first 3 subsamples were known to have relatively low overall response proportions in previous waves of DNHS [