4. Indicators based on Statistics Canada (STC) surveys

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4.1 National Population Health Survey

The National Population Health Survey (NPHS), which began in 1994/95, collects information about the health of the Canadian population every two years. It covers household and institutional residents in all provinces and territories, except persons living on Indian reserves, Canadian Forces bases, and in some remote areas. The NPHS has both a longitudinal and a cross-sectional component. Respondents who are part of the longitudinal component will be followed for up to 20 years.

The Health Indicators data are based on both the longitudinal and cross–sectional components for household residents (institutional excluded) living in the provinces (territories excluded). Data are available for the first three cycles (1994/95, 1996/97 and 1998/99).

The 1994/95 and 1996/97 cross-sectional samples are made up of longitudinal respondents and their household members and individuals who were selected as part of supplemental samples, or "buy–ins", in some provinces. The 1998/99 cross–sectional sample is made up mostly of longitudinal respondents and their cohabitants. No buy–ins were added to 1998/99 data. However, to keep the sample representative, infants born in 1995 and thereafter and immigrants who entered Canada since the beginning of 1995 were randomly selected and added to the NPHS sample.

The 1994/95 provincial, non–institutional cross–sectional sample consisted of 27,263 households, of which 88.7% agreed to participate in the survey. After application of a screening rule to maintain the representativeness of the sample, 20,725 households remained in scope. In 18,342 of these households, the selected person was aged 12 or older. Their response rate to the in–depth health questions was 96.1% or 17,626 respondents. In 1996/97, the overall response rate at the household level was 82.6%. The response rate for the randomly selected individuals aged 2 or older in these households was 95.6%. A total of 81,804 respondents answered the in depth health questions in 1996/97. In 1998/99, the overall response rate was 88.2% at the household level. The response rate for the randomly selected respondents 0 or older in these households was 98.5%. A total of 17,244 respondents answered the in depth health questions in 1998/99.

The 1994/95 provincial, non–institutional longitudinal sample consisted of 17,276 respondents. A response rate of 93.6% was achieved in 1996/97, and a response rate of 88.9% was achieved in 1998/99.

4.2 National Population Health Survey -- Northern Component

Statistics Canada conducted the northern component of the NPHS in conjunction with the statistical bureaus in Yukon and NWT. Data were obtained through a separate survey due to the special challenges of survey taking in Canada’s North.

The target population of the Yukon/NWTintegrated NPHS/ NLSCY survey included household residents living in private occupied dwellings located in the two territories, with the exclusion of populations on Indian Reserves, Canadian Forces Bases and in institutions. Moreover, persons living in unorganized areas in the Yukon (13% of the population) and persons living in unorganized areas, very small or extreme northern communities of the NWT (4.9% of the population) were also excluded from the target population.

Most of the core content from the 1994/95 NPHS main survey is included in the northern survey; however, special "focus content" on stress was excluded. In each selected household in the North, demographic information was collected from all household members, then one person, aged 12 years and over, was randomly selected for a more in–depth interview. The questionnaire included components on health status, use of health services, risk factors and demographic and socio–economic status. Some content changes were made in the 1996/97 NPHS North survey.

Collection operations ran from November 1994 to March 1995 (and again from November 1996 to March 1997). Computer–assisted personal interviewing (CAPI), used for the NPHS in the provinces, was not available in the territories at the time of the survey. A paper and pencil questionnaire designed to replicate the CAPI application was used instead. Telephone interviews were conducted where available, otherwise personal interviews were done.

The selected person response rate for the NPHS 1994/95 was 94.2% at the North level (2,020 respondents). For the Yukon this rate was 94.8%, while the rate for the NWT was 93.1%. The cross–sectional response rate at the North level (both territories) for the NPHS 1996/97 was 86.2% (1,499 respondents). For the Yukon, this rate was 83.9% while the rate for the NWT was 89.8%.

Data quality note on Heavy Drinking in the 1994/95 NPHS-North:

Due to a high proportion (42.8%) of refusals/non-stated responses to the question on frequency of heavy drinking in the 1994/95 NPHS –North, these data were deemed unreleasable/unreliable. Heavy drinking has been defined as the number of times current drinkers drank 5 or more alcoholic beverages on one occasion.

For more information about the NPHS (Household or North component), see /english/sdds/indexa.htm and look for 3225 for the Household component and 5004 for the North component.

4.3 Canadian Community Health Survey

Health region level rates from the latest survey cycle (2005) are based on the boundaries in effect as of June 2005.

Starting with data year 2000/01, the Canadian Community Health Survey (CCHS) replaces the cross-sectional aspect of the NPHS.

The primary objective of the CCHS is to provide timely cross-sectional estimates of health determinants, health status and health system utilization at a sub-provincial level (health region or combination of health regions).

The CCHS collects information from individuals aged 12 or older who are living in private dwellings. People living on Indian reserves or Crown lands, residents of institutions, full-time members of the Canadian Armed Forces, and residents of certain remote regions are excluded. The CCHS covers approximately 98% of the Canadian population aged 12 or older.

Each two–year collection cycle is comprised of two distinct surveys: a health region–level survey in the first year with a total sample of 130,000 and a provincial-level survey in the second year with a total sample of 30,000. Sample sizes in any particular month or year may increase due to provincial or health region–level sample buy–ins.

For more information about the CCHS (health region or provincial component), see /english/sdds/indexa.htm and look for 3226 for the health region component and 5015 or 5049 for the provincial components.

Data quality note on probability of depression from CCHS:
The depression module used in CCHS Cycle 3.1 (as well as in Cycles 1.1 and 2.1 and in the NPHS) is based on a long form of the Composite International Diagnostic Interview (CIDI) scale, which was developed in the late 1980s/early 1990s. This scale was never fully validated by the CIDI research team and its psychometric properties are therefore not well understood.  Statistics Canada is currently exploring strategies to complete such a validation. At this time, Statistics Canada recommends that analysis of data from this module be restricted to examination of depression as a correlate of other health behaviours and characteristics. For now, use of the data as an indicator for the probability of depression or to calculate simple population prevalence is discouraged.

4.4 National Longitudinal Survey of Children and Youth

The National Longitudinal Survey of Children and Youth (NLSCY), developed jointly by Human Resources Development Canada and Statistics Canada, is a comprehensive survey which follows the development of children in Canada and paints a picture of their lives. The survey monitors children’s development and measures the incidence of various factors that influence their development, both positively and negatively.

The first cycle of the NLSCY, which was conducted in late 1994 and early 1995, interviewed parents of approximately 23,000 children up to the age of 11. They shared information not only about their children, but also about themselves and the children's families, schools and neighbourhoods.

The second cycle, carried out in winter and spring of 1996/97, interviewed parents of the same children and provides unique insights into the evolution of children and their family environments over a two–year period. A new sample of newborn and 1–year–old children was added to cycle 2 to allow for cross-sectional estimates.

Collection of cycle 3 began in the fall of 1998 and was carried until June 1999. In addition to the original sample of children, who were aged 2 to 13 years at the time of the second data collection, a new sample of newborn and 1–year–old children was added to cycle 3 to allow for cross-sectional estimates. An extra cross–sectional sample of children 5 years old was also added to allow some provincial estimates for that age group.

For more information on the NLSCY, see /english/sdds/indexa.htm and look for 4450.

4.5 Bootstrapping

To ensure high data quality for estimates from the NPHS, the CCHS and NLSCY , a weighted bootstrap resampling procedure (and for the NPHS–North, a modified bootstrap procedure) was used to calculate coefficients of variation (CVs) for totals and rates. If the CV was greater than 33.3% or the sample size was less than 10, the data were suppressed and an ‘F’ symbol appears in the data cell. If the CV is greater than 16.5% and no greater than 33.3%, the data should be interpreted with caution and an ‘E’ symbol appears in the same cell as the data. Data with CVs of 16.5% or less are presented without restrictions.

Sampling theory dictates that sample survey results of exactly 100% or 0% must have a coefficient of variation of exactly 0. In reality it is possible that in rare circumstances the true estimate may be lower than 100% or conversely greater than 0% and results should be interpreted as such.