California Health Interview Survey


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What is CHIS?

CHIS is the nation's largest state health survey. CHIS is a web and telephone survey conducted on a continuous basis and covers a wide range of health topics. CHIS gives a detailed picture of the health and health care needs of California's large and diverse population.

The survey provides:

  • Statewide information on the overall population including many racial and ethnic groups.
  • County-level information for most counties to aid with health planning, priority setting, and to compare health outcomes in numerous ways.
  • ZIP code, city and legislative district information via our online Web tool, AskCHIS Neighborhood Edition (NE).

The survey uses a scientific sampling methodology and extensive questionnaires to collect consistent information that accurately represents California's diverse populations and geographic areas.

CHIS data are released annually in the following formats:

  • Health Profiles: Easy-to-read, one-page fact sheets containing key health statistics for the state, California counties, regions, Service Planning Areas (SPAs), and more. View all Health Profiles here.
  • Publications: The UCLA Center for Health Policy Research, which conducts CHIS, will occasionally release fact sheets, policy briefs and other publications using one-year data.  Browse Center publications here or subscribe to our e-newsletter for news about upcoming publications.
  • Data Access Center (DAC):  The Center’s Data Access Center provides researchers with access to CHIS data that are not publicly available through an approval process.  Learn more about how to access confidential CHIS data.
  • AskCHIS: A free, online tool that enables you to produce customized health statistics at the state, county, region or sub-county areas (for Los Angeles and San Diego counties).  Several years of data can be combined to create larger samples. Learn more.
  • AskCHIS Neighborhood Edition (NE): A free, online tool that enables you to generate, map and export customized estimates of California cities, ZIP codes and legislative districts. Learn more.
  • Public Use Files (PUFs):  These data files contain a full (one-year) cycle of CHIS data, enabling researchers to customize and run their own data searches. The files are available in a variety of data formats, including SAS, SPSS and STATA.
History of CHIS data collection:

Starting in 2011, CHIS transitioned from a biennial survey model to a continuous survey model, which enables a more frequent (annual) release of data.

CHIS sample sizes by year:

  • CHIS 2020 surveyed 22,661 households in 2020, including 21,949 adults, 1,365 adolescents, and 3,548 children. 
  • CHIS 2019 surveyed 22,738 households in 2019, including 22,160 adults, 847 adolescents, and 3,009 children. 
  • CHIS 2018 CHIS surveyed 21,449 households in 2018, including 21,177 adults, 432 adolescents, and 1,586 children. 
  • CHIS 2017 CHIS surveyed 21,294 households in 2017, including 21,153 adults, 448 adolescents, and 1,600 children. 
  • CHIS 2016 surveyed 21,269 households, including 21,055 adults, 840 adolescents and 2,136 children.
  • CHIS 2015 surveyed 21,444 households, including 21,034 adults, 754 adolescents and 2,157 children.
  • CHIS 2014 surveyed 20,207 households, including 19,516 adults, 1,052 adolescents and 2,592 children.
  • CHIS 2013 surveyed, including 21,304 households, including 20,724 adults, 1,201 adolescents and 2,920 children.

Biennial CHIS data were released for the following time periods: 

  • CHIS 2011-2012 surveyed 44,559 households, including 42,935 adults, 2,799 adolescents and 7,334 children.
  • CHIS 2009 surveyed more than 47,000 adults, more than 12,000 teens and children and more than 49,000 households.
  • CHIS 2007 surveyed more than 51,000 adults, more than 13,000 teens and children and more than 53,000 households, with oversampling of Los Angeles and San Diego Counties.
  • CHIS 2005 surveyed more than 45,000 households and expanded the number of individually represented California counties from 33 to 41 (with the remaining smaller counties grouped into three strata).
  • CHIS 2003 surveyed more than 42,000 households and had the added dimension of housing and neighborhood information.
  • CHIS 2001 -- the first survey -- collected information from more than 55,000 households.

CHIS is conducted by the UCLA Center for Health Policy Research in collaboration with the California Department of Public Health, and the Department of Health Care Services.

Funding for CHIS comes from state and federal agencies and from several private foundations.

The California Health Interview Survey is based in Los Angeles, Calif., at the UCLA Center for Health Policy Research, the premiere source of health policy information for California and one of the nation's leading health policy research centers.