Canadian Community Health Survey - Annual Component (CCHS)

Detailed information for 2021

The central objective of the Canadian Community Health Survey (CCHS) is to gather health-related data at the sub-provincial levels of geography (health region or combined health regions).

Data release - July 14, 2021 (March/April 2021); September 17, 2021 (January to April 2021); December 16, 2021 (June to August 2021); March 15, 2022 (Sept/Nov 2021); June 7, 2022 (Nov. 2021/Feb. 2022); Aug. 26, 2022 (Home care use); Jan. 25, 2024(2SLGBTQ+)

• Questionnaire(s) and reporting guide(s)
• Description
• Data sources and methodology
• Data accuracy

Description

In 1991, the National Task Force on Health Information cited a number of issues and problems with the health information system. To respond to these issues, the Canadian Institute for Health Information (CIHI), Statistics Canada and Health Canada joined forces to create a Health Information Roadmap. From this mandate, the Canadian Community Health Survey (CCHS) was conceived.

The CCHS is a cross-sectional survey that collects information related to health status, health care utilization and health determinants for the Canadian population. The survey is offered in both official languages. It relies upon a large sample of respondents and is designed to provide reliable estimates at the health region level every 2 years.

The CCHS has the following objectives:
- Support health surveillance programs by providing health data at the national, provincial and intra-provincial levels;
- Provide a single data source for health research on small populations and rare characteristics;
- Timely release of information easily accessible to a diverse community of users;
- Create a flexible survey instrument that includes a rapid response option to address emerging issues related to the health of the population.

The CCHS produces an annual microdata file and a file combining two years of data. The CCHS collection years with both consistent design and consistent population representation can also be combined by users to examine populations or rare characteristics.

The primary use of the CCHS data is for health surveillance and population health research. Federal and provincial departments of health and human resources, social service agencies, and other types of government agencies use the information collected from respondents to monitor, plan, implement and evaluate programs to improve the health of Canadians. Researchers from various fields use the information to conduct research to improve health. Non-profit health organizations and the media use the CCHS results to raise awareness about health, an issue of concern to all Canadians.

The survey began collecting data in 2001 and was repeated every two years until 2005. Starting in 2007, data for the Canadian Community Health Survey (CCHS) were collected annually instead of every two years. While a sample of approximately 130,000 respondents were interviewed during the reference periods of 2001, 2003 and 2005, the sample size was changed to 65,000 respondents each year starting in 2007.

In 2012, CCHS began work on a major redesign project that was completed and implemented for the 2015 cycle. The objectives of the redesign were to review the sampling methodology, adopt a new sample frame, modernize the content and review the target population. Consultations were held with federal, provincial and territorial share partners, health region authorities and academics.

As a result of the redesign, the 2015 CCHS has a new collection strategy, is drawing the sample from two different frames and has undergone major content revisions. With all these factors taken together, caution should be taken when comparing data from previous cycles to data released for the 2015 cycle onwards.

Reference period: Varies according to the question (for example: "over the last 12 months", "over the last 6 months", "during the last week", etc.)

Collection period: January 2021 to February 2022, with no collection in May 2021 due to the Census

Subjects

• Diseases and health conditions
• Health
• Health care services
• Lifestyle and social conditions
• Mental health and well-being

Data sources and methodology

Target population

The 2021 CCHS covers the population 12 years of age and over living in the ten provinces and the three territorial capitals. Excluded from the survey's coverage are: persons living on reserves and other Aboriginal settlements in the provinces; full-time members of the Canadian Forces; the institutionalized population, children aged 12-17 that are living in foster care, and persons living in the Quebec health regions of Région du Nunavik and Région des Terres-Cries-de-la-Baie-James. Altogether, these exclusions represent less than 3% of the Canadian population aged 12 and over.

Instrument design

Each component of the CCHS questionnaire is developed in collaboration with specialists from Statistics Canada, other federal and provincial departments and/or academic fields. The CCHS questions are designed for computer-assisted interviewing (CAI), meaning that, as the questions were developed, the associated logical flow into and out of the questions was programmed. This includes specifying the type of answer required, the minimum and maximum values, on-line edits associated with the question and what to do in case of item non-response.

CCHS content is comprised groups of questions (referred to as modules), which focus on a particular theme of health. These modules may be included in multiple cycles of CCHS, or may be asked only periodically. Examples of modules asked in most cycles are: general health, chronic conditions, smoking, and alcohol use. For the 2021 cycle, thematic content on food security, home care, sedentary behaviour and depression, among many others, have been included. In addition to the health component of the survey are questions about respondent characteristics such as labour market activities, income, and sociodemographics..

New modules and revisions to existing CCHS content are tested using different methods. Qualitative tests using individual cognitive interviews or, more rarely, focus groups are used to ensure that questions and concepts are appropriately worded.

The computer application for data collection is extensively tested in-house each time changes are made. The objective of these tests is to identify any errors in the program flow and text before the start of the main survey.

Sampling

This is a sample survey with a cross-sectional design.

Frame
For the 12 to 17 years old, the frame is constructed from the Canadian Child Benefit (CCB).

For the 18 years old and older, the frame is constructed from the Dwelling Universe File (DUF).

Sampling unit
For the 12 to 17 years old, the CCHS sample has a one-stage design, and the person is the sampling unit.

For the 18 years old and older, the CCHS sample has a two-stage design: the sampling unit for the first stage is the dwelling, and the sampling unit for the second stage is the person.

Stratification method
For the 12 to 17 years old, the frame is stratified by health region (HR).

For the 18 years old and older, the frame is stratified by HR, except in two provinces. In Ontario, strata are intersections of HRs and Local Health Integration Networks. In Alberta, strata are subdivisions of HRs named subzones.

Sampling and sub-sampling
For the 12 to 17 years old, the units on the frame were sorted by sex and age, and a systematic sample of individuals was selected independently within each stratum.

For the 18 years old and older, the sample has a two-stage design. First, a simple random sample of dwellings was selected independently within each stratum. During collection, all members of the dwelling are listed and a person aged 18 years or over is automatically selected using various selection probabilities based on age and household composition.

Sufficient sample was allocated to each of the provinces and HRs so that the survey could produce estimates of good quality at the national level every two months, at the provincial level each year, and at the HR level for a two-year cycle. An initial sample of 225,000 dwellings or individuals was selected and sent to collection.

Data sources

Data collection for this reference period: 2021-01-04 to 2022-01-31
No data collection took place in May 2021 due to requirements for the Census.

Responding to this survey is voluntary.

Data are collected directly from survey respondents.

Data is collected from survey respondents either through an electronic questionnaire (EQ) or through CATI (computer assisted telephone interviewing).In the case of respondents 18 years of age and older, a letter is mailed to the selected dwelling. In the letter there is a code which gives access to the online questionnaire. It informs the householder about the survey and asks that a household member access the questionnaire online with the given access code to answer some preliminary questions including all the people that reside in that dwelling. From this information, a household member aged 18 or older is then randomly selected to participate in the survey. An email containing a second code is sent to the selected respondent so that they may then answer their portion.

For respondents aged 12 to 14, a letter is addressed to the parent or legal guardian of the child (also called the Person Most Knowledgeable - PMK in the survey) requesting survey participation from the targeted child. With consent from the legal parent or guardian, and provision of an email address, the child is then contacted to answer the questionnaire.

For respondents aged 15 to 17, a letter is sent to both the PMK and also to the youth. The youth does not need formal consent from the PMK and can proceed with completing the questionnaire as soon as the letter is received.
In both cases, The PMK is then asked to complete a smaller portion of the questionnaire related to household related variables best not answered by the child respondent such as questions on, household income, insurance and food security.

A Statistics Canada interviewer may follow up by calling, emailing or texting the respondent if a completed online questionnaire is not received within a certain period of time.
Proxy reporting (when a selected respondent is unable to answer for themselves) is allowed on CCHS, although certain questions may be skipped.

The questionnaire is available in both official languages and can be completed by interview in either English or French. To remove language as a barrier to conducting interviews, each of the Statistics Canada Regional Offices recruited interviewers with a wide range of language competencies. When necessary, cases are transferred to an interviewer with the language competency needed to complete an interview. The average time to complete the survey is 50 minutes.

The information collected during the 2021 CCHS will be linked to the personal tax records (T1, T1FF or T4) of respondents, and tax records of all household members. Household information (address, postal code, and telephone number), respondent's information (social insurance number, surname, name, date of birth/age, sex) and information on other members of the household (surname, name, age, sex and relationship to respondent) are key variables for the linkage.

Respondents are notified of the planned linkage before and during the survey. Any respondents who object to the linkage of their data have their objections recorded, and no linkage to their tax data takes place. Income information obtained from income tax records will also be provided to federal, provincial and territorial share partners only with respondent consent.

View the Questionnaire(s) and reporting guide(s).

Error detection

Most editing of the data was performed at the time of the interview by the computer-assisted interviewing (CAI) application. It was not possible for interviewers to enter out-of-range values and flow errors were controlled through programmed skip patterns. For example, CAI ensured that questions that did not apply to the respondent were not asked.

In response to some types of inconsistent or unusual reporting, warning messages were invoked but no corrective action was taken at the time of the interview. Where appropriate, edits were instead developed to be performed after data collection at Head Office. Inconsistencies were usually corrected by setting one or both of the variables in question to "not stated".

Imputation

Household income data in the 2021 CCHS is imputed. Missing values due to either respondent refusal or respondent's lack of knowledge of household income are replaced using different techniques, among them a nearest neighbour imputation method based on a modeled household income

Estimation

In order for estimates produced from survey data to be representative of the covered population, and not just the sample itself, users must incorporate the survey weights in their calculations. A survey weight is given to each respondent included in the final sample. This weight corresponds to the number of persons in the entire population that are represented by the respondent.

As described above, the CCHS uses two sampling frames for its sample selection: a dwelling frame for the Canadian population aged 18 and over, and a frame of telephone numbers from Canada Child Benefit (CCB) records for the 12-17 population.

The weighting strategy treats both the dwelling and CCB frames independently to come up with separate person-level weights for each of the frames used. The adjustments applied to the initial weights are based on modeling probabilities of response (at the household level and person level). Variables derived from the collection paradata as well as characteristics of the units are used to create the models. Then these probabilities are used to create groups of respondents and nonrespondents in which to transfer the weights of the nonrespondents to the respondents. The person-level weights from the two frames are then combined into a single set of weights, jointly undergo two more adjustments (Winsorization and Calibration to known population totals such as by geography and age and sex), and become the final person-level weights.

Bootstrap weights are created through resampling the original sample and applying similar adjustments to the bootstrap weights as to the sample weights.

The steps for weighting are described in chapter 8 of the CCHS User Guide.

The sample design used for this survey was not self-weighting. That is to say, the sampling weights are not identical for all individuals in the sample. When producing simple estimates, including the production of ordinary statistical tables, users must apply the proper sampling weight.

Estimates of the number of people with a certain characteristic are obtained from the data file by summing the final weights of all records possessing the characteristic of interest.

Proportions and ratios are obtained by summing the final weights of records having the characteristic of the numerator and the denominator, and then dividing the first estimate by the second.

Quality evaluation

Throughout the collection process, control and monitoring measures were put in place and corrective action was taken to minimize non-sampling errors. These measures included response rate evaluation, reported and non-reported data evaluation, on site observation of interviews, improved collection tools for interviewers and others.

Once processing steps are completed, two data validation steps are undertaken. First, a validation program is run in order to compare estimates for the health indicators taken from the common content with the previous year. This validation is performed at various geographical levels, as well as by age and sex. Significant differences are examined further to find any anomalies in data. Also, the work of analysts who use the CCHS data to publish analytical articles on specific themes, allows for an in-depth look at many variables of the survey and represents a very effective way to find error.

Disclosure control

Statistics Canada is prohibited by law from releasing any information it collects that could identify any person, business, or organization, unless consent has been given by the respondent or as permitted by the Statistics Act. Various confidentiality rules are applied to all data that are released or published to prevent the publication or disclosure of any information deemed confidential. If necessary, data are suppressed to prevent direct or residual disclosure of identifiable data.

In order to prevent any data disclosure, confidentiality analysis is done using the Statistics Canada Generalized Disclosure Control System (G-Confid). G-Confid is used for primary suppression (direct disclosure) as well as for secondary suppression (residual disclosure). Direct disclosure occurs when the value in a tabulation cell is composed of or dominated by few enterprises while residual disclosure occurs when confidential information can be derived indirectly by piecing together information from different sources or data series.

Revisions and seasonal adjustment

This methodology does not apply to this survey.

Data accuracy

The quality of estimates produced with CCHS data is measured with the coefficient of variation (CV), produced using bootstrap weights. The CV magnitude will depend on the domain of interest and the prevalence of the characteristic.