National Health Interview Survey (NHIS)

The National Health Interview Survey (NHIS) is a key tool for monitoring population health trends and changes. Conducted every four years, it has been completed six times in Taiwan (2001, 2005, 2009, 2013, 2017, and 2021). Using a stratified, multi-stage, equal probability sampling design, the survey covers 23 counties and cities, selecting samples independently at various administrative levels. The 2021 survey had a planned sample size of 38,266 individuals, with an overall sampling rate of 1.63 per thousand. Each survey undergoes revisions to address health concerns. For instance, the 2017 NHIS covered six major areas: basic personal information (e.g., marriage, education), health status (e.g., chronic diseases, dental health, activities of daily living), accidents and injuries, health behaviors (e.g., smoking, drinking), healthcare utilization (e.g., dental care, screenings), and socioeconomic status.