Data sources, methods and definitions

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Data sources

This article is based on data from the 2012 Canadian Survey on Disability (CSD). The CSD is a survey of Canadian adults whose daily activities are limited because of a long-term condition or health-related problem.

The CSD is based on a social model of disabilities rather than a medical model. The social model is based on the premise that disability is the result of the interaction between a person’s functional limitations and barriers in the environment, such as social and physical barriers, that make it harder to function on a daily basis. Thus, disability is a social disadvantage that an unsupportive environment imposes on an individual’s impairment.^{Note 1}

Methods

The 2012 CSD was based on a sample of persons who reported an activity limitation on the 2011 National Household Survey (NHS) and who were aged 15 and over on the date of the NHS (May 10, 2011). The CSD makes it possible to validate the disability status and identify the type(s) of disability.

This study examined persons with disabilities who were aged 25 to 64 in 2011 (10,506 CSD respondents, representing 2,142,500 Canadians). These persons were compared with a sample of 69,176 respondents without a disability in the same age group, which represented 16,582,000 Canadians. In this article, most of the information, including the information on employment status, occupation, level of education and age, were collected as per the 2011 NHS.

Information on the final disability status (including severity) and information on experiences of discrimination were collected as per the 2012 CSD. The information collected in 2012 about disabilities could therefore be different from the situation that prevailed at the time of the collection of employment information (in 2011).

Definitions

Disability

To determine whether a person has a disability, disability screening questions (DSQ) were used in the CSD. The DSQ measure the type and severity of disabilities of Canadian adults by asking about how often respondents’ daily activities are limited by long-term physical or mental conditions, health problems and task-based difficulties. Screening questions in the DSQ evaluate the presence and severity of 10 distinct types of disabilities related to a health problem or condition that has lasted or is expected to last for six months or more. Screening questions emphasize consistency of measurement across disability types. The questions address the following disability types: 1. Seeing 2. Hearing 3. Mobility 4. Flexibility 5. Dexterity 6. Pain 7. Learning 8. Developmental 9. Mental/psychological 10. Memory.

For each of the 10 disability types, the DSQ always have at least one question on the associated level of difficulty (no difficulty, some difficulty, a lot of difficulty, cannot do) and one question on the frequency of the limitation of activities (never, rarely, sometimes, often, always). For a disability to be assigned to a particular type, the limitation frequency must be ‘sometimes,’ ‘often’ or ‘always,’ or ‘rarely’ combined with a difficulty level of ‘a lot’ or ‘cannot do.’

Severity

A severity score was calculated for each person with a disability. A person’s overall severity score is derived from the scores for the 10 disability types. The score is obtained by adding the severity scores for each type of severity together and dividing the sum by 10. By definition, the overall score is also a number between 0 and 1. Consequently, the more types of disability a person has, the higher his or her score will be. The score also increases with the level of difficulty associated with the disability and the frequency of the limitation of activities.

Four severity classes were established based on the overall severity score—mild, moderate, severe and very severe. In the population of 25- to 64-year-olds, 31% had a mild disability, 19%, a moderate disability, 23%, a severe disability and 27%, a very severe disability.

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