Survey on Living with Neurological Conditions in Canada (SLNCC)
Detailed information for 2011
The purpose of the Survey on Living with Neurological Conditions in Canada is to collect new information about Canadians' experiences with chronic neurological conditions. The survey will report on various factors that impact on health for individuals living with these conditions, their families and caregivers.
Data release - December 12, 2012
- Questionnaire(s) and reporting guide(s)
- Data sources and methodology
- Data accuracy
A national population study of neurological conditions was recently funded by the Government of Canada. Its purpose is to fill gaps in knowledge about individuals living with neurological conditions, their families, and caregivers. Data from this study will be used to provide a clear picture of neurological conditions in Canada and will help governments and stakeholders plan programs and health services for Canadians living with these conditions.
As part of the neurological conditions study, Statistics Canada will conduct the Survey on Living with Neurological Conditions in Canada on behalf of the Public Health Agency of Canada.
The Survey on Living with Neurological Conditions in Canada (SLNCC) is a cross-sectional survey sponsored by the Public Health Agency of Canada that will collect information related to Canadians' experiences with chronic neurological conditions. The SLNCC will focus on 18 neurological conditions including migraine headaches, multiple sclerosis, epilepsy and Alzheimer's disease.
The SLNCC asks respondents about a number of issues related to chronic neurological conditions, including diagnosis of a neurological condition, medication use, social support and the economic impact of having a neurological condition.
The survey has the following objectives:
- To assess the impact of chronic neurological conditions on quality of life, work and general well-being for individuals living with these conditions;
- To evaluate the costs associated with chronic neurological conditions including out-of-pocket expenses and loss of productivity for individuals living with these conditions;
- To analyze the impact of providing assistance on people caring for individuals living with chronic neurological conditions.
The SLNCC data will be used by the Public Health Agency of Canada, Health Canada, and provincial ministries of health to better plan and provide health services for persons with chronic neurological conditions. Researchers will be able to use the data to monitor, analyze, measure and report on factors affecting those living with chronic neurological 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 SLNCC covers the population 15 years of age and over living in the ten provinces who have been diagnosed by a health professional with one or more of the following conditions: migraine headaches, multiple sclerosis, epilepsy, cerebral palsy, spina bifida, hydrocephalus, muscular dystrophy, dystonia, Tourette's syndrome, Parkinson's disease, ALS, Huntington's disease, Alzheimer's disease or other dementia, stroke, brain or spinal cord tumours, or brain or spinal cord injuries. 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 questionnaire was developed by Statistics Canada, in collaboration with the Public Health Agency of Canada and their neurological expert groups. Qualitative testing by Statistics Canada's Questionnaire Design Resource Centre, using face-to-face interviews, was conducted in November of 2010.
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.
A set of questions targeting 18 neurological conditions was added to the 2010 and the 2011 Canadian Community Health Survey (CCHS) (see record number 3226). These questions were asked of all persons living in the household of the selected CCHS respondent. The sample for the Survey on Living with Neurological Conditions in Canada (SLNCC) was drawn from the CCHS respondents and household members aged 15 and over and living in the 10 provinces that reported being diagnosed with at least one of the 18 neurological conditions of interest.
In order to produce the most reliable estimates possible, it was decided to select every household that contained at least one person with a neurological condition, except for the two most prevalent conditions (stroke and migraine). Then a sample of households containing only persons reported to have either stroke or migraine headaches was selected. It was possible that more than one person in a household reported being diagnosed with a neurological condition. However, only one person per household was selected, giving a higher chance of being selected to those with a more rare condition than to those with stroke or migraine headaches. Individuals who reported having multiple neurological conditions were also given a higher chance of being selected.
The raw sample size is 8,200 people.
Data collection for this reference period: 2011-09-09 to 2012-03-31
Responding to this survey is voluntary.
Data are collected directly from survey respondents.
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.
No imputation is done for this statistical program.
The "weight" is defined as the number of individuals that a survey 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 persons in the population suffering from multiple sclerosis who feel that their condition has limited their educational opportunities quite a bit or extremely is estimated by summing the weights of all respondents in the sample with these characteristics. Similarly, an estimate of the proportion of people with a neurological condition who received short-term or long-term professional assistance at home, work or school in the past 12 months because of their neurological condition is computed by dividing the sum of the weights of those who answered yes to this question by the sum of weights of everyone in the sample. Since the SLNCC is a follow-up survey to the CCHS, the initial weights for the SLNCC were obtained from the 2010 and 2011 CCHS weights.
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 SLNCC is considered, a selected individual may no longer belong to the target population. This can be due to changes in neurological condition(s), death, moving to an institution, etc. In order to ensure that the SLNCC respondents truly represent the target population, initial weights are adjusted to shift the weight of non-respondents to 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 with replacement (in the case of the SLNCC, B=500). For each of the B sub-samples, an estimate of the characteristic of interest (for example, the proportion of people with a neurological condition who received short-term or long-term assistance in the past 12 months) is computed. The observed variance between the B estimates is the bootstrap variance estimator.
For the purposes of the SLNCC, the bootstrap replicates are the B sub-samples drawn and used to estimate the variance of the CCHS estimates. Each CCHS bootstrap replicate is adjusted in order to reflect the SLNCC sample design, as well as the non-response and out-of-scope adjustments. The resulting adjusted-weight replicates are considered the bootstrap replicates of the SLNCC, from which estimates of the variance are produced.
Statistics Canada has developed a program called BOOTVAR that can use bootstrap replicates to generate the variance and other measures of precision.
To ensure the survey met its objectives (see "Description"), the SLNCC was developed based on a multi-stage consultation process. A Working Group comprised of authorities from the Public Health Agency of Canada, Statistics Canada, and the Neurological Health Charities of Canada determined the concepts and focus. Experts and stakeholders advised on the selection of content and provided recommendations on appropriate and proven collection instruments and indices.
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, out-of-scope evaluation, on site observation of interviews, improved collection tools for interviewers and others.
Once processing steps were completed, a validation program was run in order to compare estimates for the content that was common with the annual Canadian Community Health Survey. This validation was performed for reported neurological conditions as well as for other common content. Significant differences were examined further to find any anomalies in data.
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.
Revisions and seasonal adjustment
This methodology does not apply to this survey.
The estimated response rate for the 2011 SLNCC was 81.6%.
Since it is an unavoidable fact that estimates from a sample survey are subject to sampling error, sound statistical practice calls for researchers to provide users with some indication of the magnitude of this sampling error. The basis for measuring the potential size of sampling errors is the standard error of the estimates derived from the survey results. However, due to the large variety of estimates that can be produced from a survey, the standard error of an estimate is usually expressed relative to the estimate to which it pertains. This resulting measure, known as the coefficient of variation (CV) of an estimate, is obtained by dividing the standard error of the estimate by the estimate itself and is expressed as a percentage of the estimate.
Statistics Canada commonly uses CV results when analyzing data and urges users producing estimates from the SLNCC data file to do so as well.
With a large number of observations, randomly occurring errors will have little effect on estimates derived from the survey. However, errors occurring systematically will contribute to biases in the survey estimates. Considerable time and effort was devoted to reducing non-sampling errors in the SLNCC. Quality assurance measures were implemented at each step of data collection and processing to monitor the quality of the data.
A major source of non-sampling errors in surveys is the effect of non-response on the survey results. The extent of non-response varies from partial non-response (failure to answer one or a few questions) to total non-response. Partial non-response to the SLNCC was minimal; once the questionnaire was started, it tended to be completed with very little non-response. Total non-response occurred either because a person refused to participate in the survey or because the interviewer was unable to contact the selected person. Total non-response was handled by adjusting the weights of persons who responded to the survey to compensate for those who did not respond.
Non-response to any particular question (item non-response) is generally low, but may be higher in some modules for various reasons. Users are cautioned to account for the larger variations during analysis, for example, by including a dummy variable for income non-response in regression analysis.
There are several reasons for which a person selected for the SLNCC could become out-of-scope including if they had died, moved to an institution or moved outside of Canada. The most prevalent reason was that the respondent reported not having any of the 18 neurological conditions of interest, contrary to what had been reported on the CCHS. This group accounted for 28.7% of all resolved SLNCC cases.
Due to the high number of out-of-scope cases on the SLNCC, it should not be used to produce prevalence estimates for the 18 neurological conditions. To produce prevalence estimates, the CCHS Neurological Conditions Prevalence Files should be used.
- Survey on Living with Neurological Conditions in Canada: Errata (June 2014)