Community Health Assessment Unit

• What is the Los Angeles County Health Survey?

  Answer:  The Los Angeles County Health Survey is a population-based survey that provides information concerning the health of Los Angeles County residents. It was initiated in 1997 and has since completed 9 waves of data collection. The LACHS includes two components: an adult survey of randomly selected adults ages 18 years and older; and a child survey administered to sufficiently knowledgeable adults about the health and daily routines of randomly selected children ages 17 years and younger. The data are used for assessing health-related needs of the population, for policy development, and for program planning and evaluation.

• What survey methodology is used for the Los Angeles County Health Survey?

  Answer:  The Los Angeles County Health Survey is designed to collect data from representative samples of county residents so as to produce estimates that can be generalized to the county population. The survey methodology has evolved over time to adopt the best practices of population-based surveys during respective survey periods. The 1997-2007 survey waves were conducted by landline telephone only random-digit-dialing (RDD), while the 2011-2018 survey waves were conducted by landline and cellphone dual frame RDD. The survey mode for these waves was Computer Assisted Telephone Interviews (CATI). Starting with the 2023 survey, address-based sampling was adopted, in which data were mainly collected via Computer Assisted Web Interviews (CAWI) with supplemental CATI for non-response follow-up. Survey sampling weights were developed to account for survey design effects and to match benchmark data and were used in the data analyses. For more detailed information, refer to the methodology reports of respective survey waves.

• What are the topics included in the survey?

  Answer:  The Los Angeles County Health Survey collects data on a broad range of health topics, such as demographics, social determinants of health, health behaviors, health care access and utilization, health outcomes, health opinions, childcare, prenatal care, and beyond. Core questions from the adult and child surveys are collected over multiple waves for trending purposes. In each survey wave, data are also collected on emerging topics or topics of interest during the data collection period. For more detailed information, refer to respective survey wave questionnaires.

• What geographies of Los Angeles County does the survey collect data on?

  Answer:  In the Los Angeles County Health Survey, data on respondents’ residential addresses were collected and geocoded to subcounty geographies such as census tracts, zip codes, cities, Health Districts, Service Planning Areas, and political districts. We routinely disseminate aggregated estimates for large subcounty geographies such as Supervisorial Districts, Service Planning Areas, and Health Districts. Data for smaller subcounty geographies are available for research collaboration projects.

• What are Supervisorial Districts?

  Answer:  There are five Supervisorial Districts in Los Angeles County. Each district is represented by a member of the Los Angeles County Board of Supervisors and contains cities and unincorporated areas. District boundaries are adjusted in the year following each Decennial Census. The most recent 2021 Supervisorial District boundaries were used for the 2023 Los Angeles County Health Survey. Find more detailed information or download Supervisorial District layers through the Los Angeles County Open Data Portal’s Supervisorial District page.
  Links: Supervisorial Districts

• What are Service Planning Areas?

  Answer:  Los Angeles County is divided into eight Service Planning Areas (SPAs) for healthcare planning purposes. These distinct regions allow Los Angeles County Department of Public Health to develop and provide more tailored public health and clinical services to meet the specific health needs of the people living in these areas. These SPA boundaries are updated to align with new U.S. Census Bureau census tract boundaries after each Decennial Census. The most recent 2022 SPA boundaries were used for the 2023 Los Angeles County Health Survey. Find more detailed information or download SPA layers through the Los Angeles County Open Data Portal’s SPA page.
  Links: Service Planning Areas (SPAs)

• What are Health Districts?

  Answer:  Health Districts (HDs) are subdivisions of Service Planning Areas in Los Angeles County. These 26 HDs are used by Los Angeles County Department of Public Health to plan and manage health service delivery across the county. HD boundaries are updated to align with the U.S. Census Bureau census tract boundaries after each Decennial Census. The most recent 2022 HD boundaries were used for the 2023 Los Angeles County Health Survey. Find more detailed information or download HD layers through the Los Angeles County Open Data Portal’s HD page.
  Links: Health Districts (HDs)

• What are the Master Data Tables?

  Answer:  To facilitate data dissemination, the Community Health Assessment Unit created Master Data Tables for key indicators collected in each survey wave. For indicators from the adult surveys, direct estimates are available for Los Angeles County overall; for demographic subpopulations defined by gender, sexual orientation, age group, race and ethnicity, educational attainment, household income (federal poverty level), and disability status; and for subcounty geographies such as Supervisorial Districts, Service Planning Areas, and Health Districts. For indicators from the child surveys, direct estimates are available for Los Angeles County overall; for child subpopulations defined by gender, age group, and race and ethnicity; for child subpopulations based on survey respondents’ characteristics such as gender, age group, race and ethnicity, educational attainment, and household income (federal poverty level); and for subcounty geographies such as Supervisorial Districts, Service Planning Areas, and Health Districts.

• What are direct estimates vs. small area estimates?

  Answer:  Direct estimates are calculated directly from the survey data. Generally speaking, the Los Angeles County Health Survey can provide stable direct estimates for large subcounty geographies such as Supervisorial Districts, Service Planning Areas, and Health Districts. Due to limited sample sizes, stable direct estimates generally cannot be generated for small subcounty geographies such as cities and communities. For select indicators from the 2023 survey, we used a model-based small area estimation approach to provide estimates for the small subcounty geographies. This approach utilized the 2023 survey data in combination with contextual data from the 2017-2021 American Community Survey and the 2022 Population and Poverty Estimates data to generate estimates. These model-based small area estimates can be downloaded from the Community Health Profiles data initiative platform.

• Why are some of the estimates not presented in the Master Data Tables?

  Answer:  To maintain data confidentiality, we suppressed estimates based on small cell sizes. A cell size is the unweighted number of respondents with a specific condition or exposure of interest. The criterion used to suppress estimates for categorical variables is cell sizes less then 5. Data suppression for continuous variables is handled in a different way as cell sizes are not applicable. We suppressed estimates with relative standard error more than 50% for continuous variables. Suppressed estimates are indicated with a hyphen (-).

• Why are some of the estimates labeled with an asterisk (*) in the Master Data Tables?

  Answer:  We routinely assess the stability (in another word, reliability) of the Los Angeles County Health Survey estimates. Starting with the 2015 survey wave, estimates are deemed unstable if their relative standard error (RSE) is more than 30%. For the survey waves prior to 2015, an RSE cut-off of 23% was used. Unstable estimates are labelled with an asterisk (*) and may not be appropriate to use for planning or policy purposes.

• Why are some of the indicators not linked to a Master Data Table?

  Answer:  Master Data Tables for the most commonly requested health indicators have been made available on our website. Some of the indicators listed do not have linked data tables because they require further contextualization in order to be assessed or because stable estimates could not be generated. If you would like to request data for an indicator that does not have a linked data table, please contact us at LAHealthData@ph.lacounty.gov.

• What are the caveats of the race and ethnicity data?

  Answer:  The questions used to collect race and ethnicity data in the Los Angeles County Health Survey have changed over time. To find more detailed information, refer to the questionnaires of each survey wave. The categorization of race and ethnicity has changed over time as well. In the survey waves of 1997-2018, race and ethnicity categories were created by the following hierarchy: Hispanic/Latinx, Black, Native Hawaiian or Pacific Islander (NHPI), Asian, American Indian/Alaska Native (AI/AN), Multiracial/Other race and ethnicity, and White alone. Starting with the 2023 survey wave, race and ethnicity was defined according to the Los Angeles County Department of Public Health Standard of Practice for collecting and reporting race and ethnicity data, in which Hispanic/Latinx includes all racial groups with Hispanic origin and the non-Hispanic racial and ethnic groups include White alone, Black alone, Asian alone, NHPI alone, AI/AN alone, and Multiracial/Other race and ethnicity.

• Why are some indicators presented at both the household level and the individual level?

  Answer:  A small number of indicators collected in the survey are at the household level (e.g., household food insecurity status and housing burden). These indicators can be analyzed by using either household weights or individual weights (also called population weights). Household level data by individual characteristics should be interpreted with caution as one adult was randomly selected from a household with multiple adults, and the selected adult’s individual characteristics (e.g., age, race and ethnicity, educational attainment, etc.) may not be the same as the other adult(s) not selected for the survey. We therefore recommend using individual level data for subgroups defined by individual characteristics (e.g., food insecurity by educational attainment level). Furthermore, indicator descriptions should properly reflect the level of the data. Using food insecurity as an example, data at the household level should be framed as the percentage or number of households experiencing food insecurity. In contrast, data at the individual level should be framed as the percentage or number of adults whose households are experiencing food insecurity.

• How can I obtain data on the Los Angeles County Health Survey?

  Answer:  You may start with accessing and downloading the Master Data Tables and reports that are posted on the website. If you need aggregated data that are not included in the Master Data Tables, please email us at LAHealthData@ph.lacounty.gov to make a customized data request. If you need raw data for research purposes, you may contact us as well. For more information on how to access and request survey data, check the “Request Data” section listed on the website.
  Links: Request Los Angeles County Health Survey Data

• How do I cite the Los Angeles County Health Survey data?

  Answer:  The suggested citation is “Data are from the (survey year) Los Angeles County Health Survey, released by the Office of Health Assessment and Epidemiology at the Los Angeles County Department of Public Health.”