Survey on Living with Chronic Diseases in Canada (SLCDC)
Detailed information for 2009 (arthritis and hypertension)
Every 2 years
The purpose of the Survey on Living with Chronic Diseases in Canada (SLCDC) is to provide information on the impact of chronic disease on individuals, as well as how people with chronic disease manage their health condition.
Data release - December 10, 2009
- Questionnaire(s) and reporting guide(s)
- Data sources and methodology
- Data accuracy
The SLCDC is a cross-sectional survey sponsored by the Public Health Agency of Canada that collects information related to the experiences of Canadians with chronic health conditions. The SLCDC will take place every two years, with two chronic diseases covered in each survey cycle.
The SLCDC asks respondents about a number of issues related to chronic health conditions, including diagnosis of a chronic health condition, care received from health professionals, medication use and self-management of their condition. The survey has the following objectives:
- To assess the impact of chronic health conditions on quality of life
- To provide more information on how people manage their chronic health conditions
- To identify health behaviors which influence disease outcomes
- To identify barriers to self-management of chronic health conditions
The SLCDC data can be used by governments to better plan and provide health services for persons with chronic health conditions and to develop public education campaigns primarily aimed at health promotion and disease prevention. Researchers will be able to use the data to monitor, analyse, measure and report on those factors affecting chronic health conditions.
Reference period: Varies according to the question (for example: "currently" or "during the past month", etc.)
- Diseases and health conditions
Data sources and methodology
The SLCDC covers the population 20 years of age and over living in the ten provinces who have been diagnosed by a health professional with one or both of the following conditions: arthritis or hypertension. Excluded from the survey coverage are: persons living on reserves and other Aboriginal settlements; full-time members of the Canadian Forces; the institutionalized population 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 overall Canadian population.
The two questionnaires were developed by Statistics Canada, in collaboration with the Public Health Agency of Canada and their arthritis and hypertension expert groups. Qualitative testing by Statistics Canada's Questionnaire Design Resource Centre, using face-to-face interviews, was conducted in May and June of 2008.
The 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.
This is a sample survey with a cross-sectional design.
The sample for this survey was drawn from respondents of the 2008 Canadian Community Health Survey (CCHS) (see record number 3226). In order to produce reliable estimates by age and sex groups, it was determined that a sample of 11,300 respondents was necessary. Respondents from the 2008 CCHS were stratified by age and sex, and the sample was randomly selected from each stratum in proportion to its size. Only the CCHS respondent, not the whole household, was eligible for selection.
It should be noted that more respondents were selected than necessary during sample selection to lessen the effect of non-response and out-of-scope units (for example, respondents who moved outside of Canada or indicated that they no longer had the condition.) The raw sample size is 16,200 respondents.
Data collection for this reference period: 2009-02-03 to 2009-03-31
Responding to this survey is voluntary.
Data are collected directly from survey respondents.
Proxy interviews are not permitted. Respondents are interviewed using a computer assisted telephone interview (CATI) system.
View the Questionnaire(s) and reporting guide(s).
Some editing of the data is performed at the time of the interview by the computer-assisted interviewing (CAI) application. It is not possible for interviewers to enter out-of-range values and flow errors are controlled through programmed skip patterns. For example, CAI ensures that questions that do not apply to a respondent are not asked. In response to some types of inconsistent or unusual reporting, warning messages are invoked but no corrective action is taken at the time of the interview.
Several edits are performed at Head Office during the data processing step. Inconsistencies are usually corrected by setting one or both of the variables in question to "not stated". A critical error edit is done that rejects respondent entries (for instance, excluded populations). Flow errors are also adjusted during processing and a data inconsistency detection and correction program is applied.
There is no imputation in the SLCDC.
The "weight" is defined as the number of individuals that a participant represents in the target population, including him- or herself. The sum of the weights of all individuals in the sample should equal the size of the target population. The principle behind estimation consists of using weights to assess the prevalence of a characteristic by extrapolating from the sample to the target population. For example, the number of women in the population aged 45 to 65 years old and suffering from hypertension is estimated by summing the weights of all women in the sample with those characteristics. Similarly, an estimate of the proportion of arthritis sufferers in the target population who are male is computed by dividing the sum of the weights of men with arthritis by the sum of weights of everyone (male and female) with arthritis. Since the SLCDC is a follow-up survey to the CCHS, the initial weights for the SLCDC were obtained from the final weights of the CCHS.
Once selected, individuals may fail to respond to surveys for any number of reasons (refusal, inability, unavailability during attempts to contact them, etc.). When more up-to-date information from the SLCDC is considered, a selected individual may no longer belong to the target population. In order to ensure that SLCDC respondents truly represent the target population, initial weights are adjusted to shift weight from non-respondents onto respondents. Selected individuals who are no longer part of the target population are removed from the file.
To measure the precision of the generated estimates, the variance must be computed. Owing to the complexity of the sample design, it is very difficult to obtain an expression for the variance. Therefore, the variance is estimated using the method known as bootstrap replication. This method consists of drawing B sub-samples from the full sample (in the case of the SLCDC, generally B=500) with replacement. For each of the B sub-samples, an estimate of the characteristic of interest (for example, the proportion of men suffering from hypertension) is computed. The observed variance between the B estimates is the bootstrap variance estimator.
For purposes of the SLCDC, the bootstrap replications are the B sub-samples used to estimate the variance of the CCHS. For each bootstrap replication of the CCHS, weights are adjusted in the same way as during the sample design. The resulting adjusted-weight replications are considered bootstrap replications of the SLCDC, from which estimates of the variance are produced.
Statistics Canada has developed a program called bootvar that can use bootstrap samples to generate variance and the corresponding measures of precision.
Throughout the collection and processing processes, 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, follow-ups with respondents, improvement of collection tools for interviewers and others.
Statistics Canada is prohibited by law from releasing any information it collects which 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.
Revisions and seasonal adjustment
This methodology does not apply to this survey.
The response rate for the 2009 SLCDC was 78%.
Please refer to Chapter 9.0 (Data Quality) of the User Guide for detailed information.
- Survey on Living with Chronic Diseases in Canada - User Guide - 2009
The purpose of this document is to facilitate the manipulation of the SLCDC data file and to describe the methodology used.
- Survey on Living with Chronic Diseases in Canada (SLCDC) - Erratum (June 2010)
- Survey on Living with Chronic Diseases in Canada (SLCDC) - Erratum (March 2012)