The California Health Interview Survey (CHIS) is a telephone survey that uses a dual-frame random-digit-dial (RDD) technique. By using traditional landline RDD and cell-phone RDD sampling frames, it is representative of the state's population. A supplemental surname list frame is used to ensure representation of the Korean and Vietnamese households.
CHIS data can be analyzed at the county level for the state's 41 most populated counties. The remaining 17 counties are combined into three different groups. See sample design summaries below.
CHIS asks questions that are shared across age groups and also some questions that are unique to only one age group: children (0-11 years of age), adolescents (12-17 years of age), and adults (18 years and older).
With a large sample of a diverse population, CHIS data have great ability to report on racial/ethnic differences.