California Health Interview Survey


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  Diverse data

CHIS 2018 contains population-based data on representative Californians, including under-surveyed racial, ethnic and sexual-minority groups. CHIS is conducted in English, Spanish, Chinese (Cantonese and Mandarin), Korean, Tagalog and Vietnamese. CHIS's rich data on numerous racial and ethnic groups has made it a valuable resource to researchers nation-wide.


 Did you know?


CHIS 2020 surveyed 22,661 households in 2020, including 21,949 adults, 1,365 adolescents, and 3,548 children. 

Who does CHIS interview?

Thousands of California households are selected each year by the California Health Interview Survey (CHIS) as part of a scientific sample representing the entire state's diverse population. From each household, a random adult, teen and child are asked to participate. CHIS is well known for its hard-to-find data on special subgroups and provides relatively robust samples of major racial/ethnic groups, sexual minorities, and other populations living in California.

Beginning in 2019, CHIS switched from a sample of telephone numbers to a sample of addresses. Moving to an address-based sample improves the coverage of California households, allows for more modes of contact and data collection, and counteracts declining participation by telephone due to the rise of spam calls, robocalls, and call blocking. CHIS now allows for randomly selected households to complete the survey on the web or by telephone. Such innovations help CHIS accurately represent California's dynamic population.

How does CHIS work?

Computers randomly draw a sample of addresses in each of 44 geographic areas (sampling strata) that represent 41 individual counties and 3 groupings of counties with smaller populations together. These areas represent the entire state.

When CHIS contacts a household, one adult is randomly selected to participate in the survey. In addition, a teenager (ages 12 to 17) and/or a child (ages 11 and under) may be randomly selected, depending on the household's composition.  These teen and child interviews allow CHIS to track important health conditions and health behaviors of teens and children in California.


The large CHIS sample includes people from many ethnic groups to provide health-related information for most large and small racial and ethnic populations that all are a part of California. To represent California's diverse population and ensure that all ethnic groups can have a voice in representing the health of California, CHIS is conducted in English, Spanish, Chinese (Cantonese and Mandarin dialects), Korean, Tagalog and Vietnamese.

See a complete list of downloadable tables that show the number of people CHIS has interviewed for each county and by race/ethnicity for each survey cycle here.