Sample Design

Overview

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. 

Given changes in the telephone survey landscape in recent years, CHIS is transitioning to a new sample design beginning in 2019. You can read more about the new methods here.

Geographic groups

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. 

Age groups

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).

Race/ethnicity groups

With a large sample of a diverse population, CHIS data have great ability to report on racial/ethnic differences.

CHIS 2017-2018

• 2018 Sample Size by County, Age, and Race/Ethnicity
  See actual sample numbers by county and by race, for each age group.
• 2017 Sample Size by County, Age, and Race/Ethnicity
  See actual sample numbers by county and by race, for each age group.
• Sample Design Description 
  Read the design plan for achieving this survey cycle's sampling goals.

CHIS 2015-2016

• 2016 Sample Size by County, Age, and Race/Ethnicity
  See actual sample numbers by county and by race, for each age group.
• 2015 Sample Size by County, Age, and Race/Ethnicity 
  See actual sample numbers by county and by race, for each age group.
• Sample Design Description 
  Read the design plan for achieving this survey cycle's sampling goals.

CHIS 2013-2014

• 2014 Sample Size by County, Age, and Race/Ethnicity 
  See actual sample numbers by county and by race, for each age group.
• 2013 Sample Size by County, Age, and Race/Ethnicity 
  See actual sample numbers by county and by race, for each age group.
• Sample Design Description 
  Read the design plan for achieving this survey cycle's sampling goals.

CHIS 2011-2012

• Sample Size by County, Age, and Race/Ethnicity 
  See actual sample numbers by county and by race, for each age group.
• Sample Design Description 
  Read the design plan for achieving this survey cycle's sampling goals.

CHIS 2009

• Sample Size by County, Age, and Race/Ethnicity 
  See actual sample numbers by county and by race, for each age group.
• Sample Design Description 
  Read the design plan for achieving this survey cycle's sampling goals.

CHIS 2007

• Sample Size by County, Age, and Race/Ethnicity
  See actual sample numbers by county and by race, for each age group.
• Sample Design Description 
  Read the design plan for achieving this survey cycle's sampling goals.

CHIS 2005

• Sample Size by County, Age, and Race/Ethnicity 
  See actual sample numbers by county and by race, for each age group.
• Sample Design Description 
  Read the design plan for achieving this survey cycle's sampling goals.

CHIS 2003

• Sample Size by County, Age, and Race/Ethnicity 
  See actual sample numbers by county and by race, for each age group.
• Sample Design Description (PDF, 176k)
  Read the design plan for achieving this survey cycle's sampling goals.

CHIS 2001

• Sample Size by County and Age  
  See actual sample numbers by county, for each age group.
• Sample Size by Age and Race/Ethnicity 
  See actual sample numbers by race/ethnicity, for each age group.
• Sample Design Description 
  Read the design plan for achieving this survey cycle's sampling goals.