The Data Access Center (DAC) based at the UCLA Center for Health Policy Research provides services to analyze California Health Interview Survey (CHIS) data in a secure, controlled environment that protects the confidentiality of respondents.

Researchers can analyze data remotely, either by:

  1. Using the programming services of the UCLA Center for Health Policy Research’s Statistical Support and Programming unit.
  2. Writing their own programming code and e-mailing it to the DAC programmers. (This option is facilitated by “dummy” data files that allow researchers to develop their own error free code without the risk of inappropriate disclosure.)

The DAC staff will create custom data files for research projects based on the variables and specifications submitted with the DAC Project Application. In addition, researchers may supply their own data to be merged with CHIS data. Supplied data may consist of proprietary data collected and owned by the researcher or other publicly available data obtained by the researcher. Researchers are to specify in their DAC Project Application any data proposed for merging with CHIS data. The DAC will not provide access to researcher-supplied files to anyone without prior written consent of the researcher who supplied the files. Merged data files containing CHIS data may not be removed from the DAC.

Prospective researchers interested in using CHIS variables that are not available in the Public Use Files (PUFs) for their project should submit a confidential DAC project application using the CHIS Online Application Portal. Through the application portal, researchers can edit and check the status of their applications and keep track of active, pending, and expired projects.

The DAC Coordinator will review each application to ensure that it is thoroughly completed. If additional materials or information are needed, the DAC Coordinator will correspond with the researcher.

Application requirements:

  • Project Variable List: Download the Master Variable List and select all variables needed for your research project within the appropriate years. After you select your variables, you will upload the document on Step 4 of the application. This document will be used to create a custom dataset for your project. Instructions on how to fill out the Master Variable List are found on the first tab of the document. For more information about CHIS variables, including universes and response categories, please review our source data dictionaries on our Resources page.
  • Non-Disclosure Agreements: All who come into contact with confidential data (principal investigator, key personnel, co-investigators, etc.) must be listed on the application, agree to the terms, and sign the CHIS Non-Disclosure Agreement.
  • Research Proposal: Please describe the nature of your research including background, methods, analysis plans, as well as publication and dissemination plans.
  • Cover Letter: Please specify your name, affiliation, address, contact information, and a brief description of your intended research.
  • Biographical Sketch or Resume: All listed on the application must submit a short biographical sketch. We ask that you combine these into one document that is no more than 5 pages.
  • IRB Approval: CHIS staff with access to confidential CHIS data are also required to submit a confirmation of IRB approval (other UCLA-based researchers do not need  to submit an IRB application the UCLA IRB). If you are a UCLA-based researcher who is not CHIS staff, your completed application does not need review by the UCLA Institutional Review Board (IRB) for DAC approval. Do not submit your research project for IRB review unless instructed to do so by DAC staff. If you, or anyone on your project team, are CHIS staff with access to confidential CHIS data, you are required to obtain UCLA IRB approval and submit a copy of the approval with your DAC application. If you are not a UCLA-based researcher, please consult with your local IRB to determine the appropriate review of your proposed research project.
  • Note: R and STATA Packages: If your project analysis will be conducted using R or STATA, please consult our list of approved and available packages for use for DAC projects. If your project requires R or STATA packages that are not on this list, please contact the Data Access Center for more information as there may be additional costs associated with the need for our team to investigate, review, and approve R or STATA packages not on the list to ensure that any package moved to our secure server is safe and doesn't compromise CHIS respondents' data. Hourly consulting rates ($175/hour) may apply to this additional work.

The completed application will then be reviewed by the Data Disclosure Review Committee (DDRC), which will make a recommendation to the CHIS Principal Investigator to approve, request further information, or reject the application. Criteria for project approval include feasibility, minimal risk of disclosure of confidential information, and consistency with the purpose of CHIS. Researchers are encouraged to develop their proposal in consultation with the DAC Coordinator. Researchers will generally receive a response within two weeks from receipt of their completed application.


Confidentiality Assurances

Researchers with projects approved by the CHIS Principal Investigator will be asked to sign a DAC Nondisclosure Affidavit prior to beginning work. All printed or electronic materials provided to researchers from the DAC are carefully screened to minimize the risk of disclosure of confidential information.

Cost estimates for individual projects vary and depend on the services needed. Other factors that affect total project costs include the extent of planned analysis, type of analysis, and the number of data runs. Please note that there is a minimum cost of $1,000 for a Data Access Center Project. DAC researchers can pay by check, invoice, or recharge payments (UC campus only).
 

Data Access Center Service

Rate per Hour

Data Set Creation (one-time cost)

$500

Programming

$175

Consulting

$175

Mapping

$175

Running program

$125

Computing time

$90

Disclosure review (extensive)

$125

Programming - expedited

$260

Mapping - expedited

$260

Running program - expedited

$185

Computing time - expedited

$135

Disclosure review (extensive) - expedited

$185


Note: Running Program and Computing Time: Services will be charged per run. If your project requires a running time of more than 8 hours, please note that you will be charged the "Running program" rate for the first 8 hours, and then the "Computing" rate for the remaining hours. For example, if a program runs for 10 hours, the first 8 hours will be charged as "Running program" ($125 x 8 = $1,000) and the remaining 2 hours will be as "Computing" ($90 x 2 = $180). The total amount would be $1,180 for the 10 hours of services.

Please also note that research projects may exceed initial cost estimates due to additional requests for DAC services. Researchers who request DAC services to be completed on an urgent basis (i.e., the same or next business day) may be subject to expedited rates, as shown in the above DAC rates table. The Data Access Center will continue to bill projects on a monthly basis for extended projects. Invoices will be sent during the subsequent month and will detail DAC services based on 15-minute increments.

The UCLA South General Institutional Review Board (IRB) has approved the DAC to conduct analyses of confidential CHIS data (CHIS protocol IRB#17-000362) via the DAC IRB protocol (IRB#11-002227). Researchers who are affiliated with UCLA should NOT submit an application to the UCLA Human Subjects Protection Committee (IRB). Researchers who are not affiliated with UCLA should consult with their local IRB to determine the appropriate review of their proposed research, but are not required to submit proof of IRB approval to the DAC. CHIS staff are required to obtain UCLA IRB approval and submit a copy of the approval with their DAC application.

All DAC projects will expire two years after the date of the CHIS Principal Investigator’s project approval. Researchers who wish to continue working on projects that are about to expire must complete a DAC Renewal Application. Researchers who have previously been approved to access confidential CHIS data and wish to expand their original project to use data from another CHIS cycle and/or request additional age groups must submit a DAC Expansion Application. The requested variable list for the project expansion must match the approved variable list from the originally approved project. Researchers who wish to add variables to their project must complete an Additional Variable Request Application.

The DAC operates by following policies and procedures approved by the UCLA Office of the Human Research Protection Program (OHRPP) and the State of California’s Committee for the Protection of Human Subjects (CPHS). The DDRC is responsible for implementing the confidentiality policies adopted by the CHIS Principal Investigator and approved by OHRPP and CPHS. The DDRC’s main tasks include:
 

  • Review of data files, data products, and data requests to ensure that CHIS respondents’ privacy and confidentiality are not violated;
  • Review of CHIS variables and recommended confidentiality and sensitivity levels;
  • Make recommendations on disclosure limitation techniques for the public use files (PUFs); and
  • Review of applications to use confidential data through the DAC.

Students interested in using confidential CHIS data for their thesis, dissertation, or other class project are required to provide evidence of faculty sponsorship in addition to the DAC Project Application in the form of a brief letter from a faculty member stating that they are acting as the faculty sponsor/adviser for the project, and that they have reviewed and approved the student’s research proposal.

Students may also submit a Student Application that allows them to apply for a limited number of scholarships based on financial need and availability of resources that partially subsidize the costs of accessing confidential CHIS data. The scholarship covers a portion of DAC fees that other users would normally pay. Submitting a student application does not guarantee that the scholarship will be awarded.

Researchers may use the CHIS dummy file datasets to check their programming code for errors prior to submitting code to be run on confidential data files through the Data Access Center. Dummy data files do not contain real data and are only provided solely for the purpose of testing statistical software programming code and syntax. 

What are Dummy Data Files? Dummy data files are created for the sole purpose of testing statistical software programming code and syntax. The values assigned to observations in dummy data files are hypothetical and not observed values. Data in the dummy files are generated to mimic certain characteristics of the confidential CHIS data file such as variable distributions. No special efforts were made to preserve associations between variables during the value assignment process. This means that results which are derived from analyzing the dummy data may not be consistent with results produced from the public use files (PUF) or confidential CHIS data files. 

How can Dummy Data Files help me? Dummy data should only be used to test programming code and syntax. Dummy data should not be reported as valid data. The dummy data files cannot be used for any inference purposes, such as creating population estimates, assessing associations between variables, or determining inter-variable relationships. Dummy data cannot be used to assess whether a model run on the confidential data will converge or produce meaningful results.

How are the Dummy Data Files structured? To aid in checking program code, each dummy data file contain nearly every variable that is available to researchers in the confidential data files. Beginning with CHIS 2005, the total sample sizes are identical to those in the confidential data files for each respective CHIS cycle. The sample size for the CHIS 2001 and 2003 dummy data files contain 5,000 records for the adult file, 5,000 records for the child file, and 3,000 records for the teen file. Household information cannot be determined by linking the adult respondents to the teen and/or child respondents in the dummy data files.

As a courtesy to researchers, efforts were made to approximate the unweighted distributions for the variables in the post-2003 dummy data files. This information can be used to aid researchers in identifying categories with small sample sizes. However, these distributions are not valid for any subpopulations of the data. Moreover, because population weight values have been randomly assigned to observations, weighted distributions in the dummy data files will not match those from the public use or confidential data files. Variables with character formats, such as verbatim responses, are not included in the dummy data files. 

How can I prepare the Dummy Data for analysis? Dummy data code can be used by researchers to analyze dummy data that contain approved CHIS variables from the Master Variable List. Researchers can run this code to remove variables that are not approved for use in DAC projects before writing code for dummy data and submitting DAC data requests. The researchers can simply change the file paths and run the code after downloading dummy data files. This code is available in SAS and Stata formats. Download the instructions and code for preparing Dummy Data Files.

When are Dummy Data Files updated? Dummy data files are generally released on the DAC website after the release of the public use data files for each CHIS cycle. However, subsequent updates to the confidential and public use file datasets may occur after the release of the dummy datasets. When this occurs, there may be lag time between release of an updated public use file and an updated dummy data file. This means that there may be minor inconsistencies between the variable distributions in the dummy files and those in the PUF or confidential datasets between any given period of time. Researchers are encouraged to check back periodically for updated versions of the dummy data files on the DAC website. In the meantime, researchers may refer to the most recent version of the Data Dictionaries which contain unweighted variable distributions for the most recently updated datasets. Patch files may also be temporarily available for download with the dummy data, until updated versions of the dummy data files are made available. The goal of these patch files is to provide timely data updates by modifying the characteristics of existing variables, providing additional variables or dropping obsolete variables in the original dummy data files. 
 

Select a year below to download:

CHIS 2022

Adult

SAS (30 KB)

Stata (59 KB)

SPSS (51 KB)

Adolescent

SAS (1 MB)

Stata (2 KB)

SPSS (1 MB)

Child

SAS (2 KB)

Stata (4 KB)

SPSS (4 MB)

CHIS 2021

Adult

SAS (34 MB)

Stata (67 MB)

SPSS (58 MB)

Adolescent

SAS (1 MB)

Stata (2 MB)

SPSS (2 MB)

Child

SAS (3 MB)

Stata (5 MB)

SPSS (4 MB)

CHIS 2020

Adult

SAS (25 MB) 

Stata (51 MB)

SPSS (45 MB)

Adolescent

SAS (1 MB)

Stata (1.5 MB)

SPSS (1.5 MB)

Child

SAS (2 MB)

Stata (3.5 MB)

SPSS (3 MB)

CHIS 2019

Adult

SAS (25 MB)

Stata (47.9 MB)

SPSS (42.4 MB)

Adolescent

SAS (0.3 MB)

Stata (0.5 MB)

SPSS (0.4 MB)

Child

SAS (0.8 MB)

Stata (1.6 MB)

SPSS (1.4 MB)

CHIS 2018

Adult

SAS (25 MB)

Stata (47.9 MB)

SPSS (42.4 MB)

Adolescent

SAS (0.3 MB)

Stata (0.5 MB)

SPSS (0.4 MB)

Child

SAS (0.8 MB)

Stata (1.6 MB)

SPSS (1.4 MB)

CHIS 2017

Adult

SAS (23.4 MB)

Stata (23.2 MB)

SPSS (18.3 MB)

Adolescent

SAS (1 MB)

Stata (1 MB)

SPSS (1 MB)

Child

SAS (1.1 MB)

Stata (1.1 MB)

SPSS (1 MB)

CHIS 2016

Adult

SAS (23.2 MB)

Stata (22.5 MB)

SPSS (17.8 MB)

Adolescent

SAS (1 MB)

Stata (1 MB)

SPSS (1 MB)

Child

SAS (1 MB)

Stata (1.1 MB)

SPSS (1 MB)

CHIS 2015

Adult

SAS (21.7 MB)

Stata (21.6 MB)

SPSS (16.8 MB)

Adolescent

SAS (1 MB)

Stata (1 MB)

SPSS (1 MB)

Child

SAS (1.2 MB)

Stata (1 MB)

SPSS (1 MB)

CHIS 2014

Adult

SAS (20.4 MB)

Stata (20.6 MB)

SPSS (16.2 MB)

Adolescent

SAS (1 MB)

Stata (1 MB)

SPSS (1 MB)

Child

SAS (1.3 MB)

Stata (1.3 MB)

SPSS (1 MB)

CHIS 2013

Adult

SAS (22 MB)

Stata (22.3 MB)

SPSS (17.4MB)

Adolescent

SAS (1 MB)

Stata (1 MB)

SPSS (1 MB)

Child

SAS (1.4 MB)

Stata (1.4 MB)

SPSS (1.1 MB)

CHIS 2012

Adult

SAS (44.8 MB)

Stata (45.5 MB)

SPSS (36.7 MB)

Adolescent

SAS (1.4.MB)

Stata (1.4 MB)

SPSS (1.2 MB)

Child

SAS (3.5 MB)

Stata (3.5 MB)

SPSS (2.6 MB)

CHIS 2011

Adult

SAS (44.8 MB)

Stata (45.5 MB)

SPSS (36.7 MB)

Adolescent

SAS (1.4.MB)

Stata (1.4 MB)

SPSS (1.2 MB)

Child

SAS (3.5 MB)

Stata (3.5 MB)

SPSS (2.6 MB)

CHIS 2009

Adult

SAS (46.7 MB)

Stata (24.5 MB)

SPSS (41.2 MB)

Adolescent

SAS (1.4MB)

Stata (1 MB)

SPSS (1.2 MB)

Child

SAS (3.7 MB)

Stata (2.2 MB)

SPSS (3.2 MB)

CHIS 2007

Adult

SAS (26 MB)

Stata (17.5 MB)

SPSS (22.4 MB)

Adolescent

SAS (1.6 MB)

Stata (1 MB)

SPSS (1.4 MB)

Child

SAS (4 MB)

Stata (2.4 MB)

SPSS (3.3 MB)

CHIS 2005

Adult

SAS (21 MB) 

Stata (16.2 MB)

SPSS (15 MB)

Adolescent

SAS (1.1 MB)

Stata (1 MB)

SPSS (1 MB)

Child

SAS (2.5 MB)

Stata (2.95 MB)

SPSS (1.8 MB)

CHIS 2003

Adult

SAS (5.9 MB)

Stata (3.0 MB)

SPSS (4.8 MB)

Adolescent

SAS (3.1 MB)

Stata (1.5 MB)

SPSS (2.6 MB)

Child

SAS (5.1 MB)

Stata (2.4 MB)

SPSS (4.2 MB)

CHIS 2001

Adult

SAS (6.3 MB)

Stata (3.6 MB)

SPSS (5.6 MB)

Adolescent

SAS (3.2 MB)

Stata (2.1 MB)

SPSS (2.6 MB)

Child

SAS (5.1 MB)

Stata (3.2 MB)

SPSS (4.3 MB)

Application Requirements

chis data access center

Project Variable List

Download the Master Variable List and select all variables needed for your research project within the appropriate years. After you select your variables, you will upload the document on Step 4 of the application. This document will be used to create a custom dataset for your project. Instructions on how to fill out the Master Variable List are found on the first tab of the document. For more information about CHIS variables, including universes and response categories, please review our source data dictionaries on our Resources page.

Non-Disclosure Agreements

All who come into contact with confidential data (principal investigator, key personnel, co-investigators, etc.) must be listed on the application, agree to the terms, and sign the CHIS Non-Disclosure Agreement.

DAC Data Access Center Banner Photo

Research Proposal

Please describe the nature of your research including background, methods, analysis plans, as well as publication and dissemination plans.

Cover Letter

Please specify your name, affiliation, address, contact information, and a brief description of your intended research.

training

Biographical Sketch or Resume

All listed on the application must submit a short biographical sketch. We ask that you combine these into one document that is no more than 5 pages.


 

IRB Approval

CHIS staff with access to confidential CHIS data are also required to submit a confirmation of IRB approval (other UCLA-based researchers do not need  to submit an IRB application the UCLA IRB). If you are a UCLA-based researcher who is not CHIS staff, your completed application does not need review by the UCLA Institutional Review Board (IRB) for DAC approval. Do not submit your research project for IRB review unless instructed to do so by DAC staff. If you, or anyone on your project team, are CHIS staff with access to confidential CHIS data, you are required to obtain UCLA IRB approval and submit a copy of the approval with your DAC application. If you are not a UCLA-based researcher, please consult with your local IRB to determine the appropriate review of your proposed research project.

Note: R and STATA Packages: If your project analysis will be conducted using R or STATA, please consult our list of approved and available packages for use for DAC projects. If your project requires R or STATA packages that are not on this list, please contact the Data Access Center for more information as there may be additional costs associated with the need for our team to investigate, review, and approve R or STATA packages not on the list to ensure that any package moved to our secure server is safe and doesn't compromise CHIS respondents' data. Hourly consulting rates ($175/hour) may apply to this additional work.