Community-based Sociodemographic Questionnaire Validation

Respondents were recruited from a wide range of sociodemographic settings to broadly represent the targets for the application of the questionnaire in the future. Individuals were included if they were above age 18 years and able to read or understand Danish. Potential respondents were randomly approached by trained interviewers in a variety of locations in the broader community, such as in libraries, private sector workplaces, a hospital, nursing homes, health centers, and an outpatient clinic. To ensure inclusion of people who may have low literacy, potential respondents were given the option of completing the questionnaire themselves or to have it read aloud in an interview. If respondents did not have time to finish the questionnaire, they were encouraged to complete it at home and were provided with a reply-paid envelope. They also had the option of completing a Web-based questionnaire.
Demographic data including age, sex, educational background, self-reported health condition, and presence of chronic conditions were also collected to evaluate whether the resulting scales were invariant to these exogenous factors and thus provided unbiased estimates of mean differences across these groups.
The administration of the questionnaires also included the administration of a validation version of the eHealth literacy assessment toolkit, which is reported elsewhere (personal communication, Karnoe 2017). Respondents did not receive any payment for filling out the questionnaire.