Health Indicators - Technical Notes

82-221-XIE

Health Indicators

April 2001

Technical Notes

Appendix 1

Population estimates

In summary, the population estimates for the health regions in this publication were prepared as follows. First, the 1996 population estimates were based on the 1996 Census, adjusted for net undercoverage. Secondly, for non-census years, the Census-based population estimates were adjusted for changes in the population, primarily using administrative data. Lastly, subprovincial/subterritorial population estimates were controlled to sum to the population estimates at the provincial/territorial level prepared by Statistics Canada.

Statistics Canada methodology

For health regions in all provinces/territories¹ except for Quebec and British Columbia, the method is that of Statistics Canada, described below. These estimates are based on census data and on population estimates by census division (CD) produced by Demography Division.

Population universe

The population included in these estimates is based on the 1991 and 1996 Census of Canada. The universe, therefore, corresponds to the census universe, which includes Canadian citizens and landed immigrants with a usual place of residence in Canada (or abroad on a Canadian Forces base, attached to a diplomatic mission or aboard merchant vessels) and non-permanent residents. For a complete description of the census universe, refer to the 1996 Census Dictionary, Statistics Canada Catalogue no 92-351-XPE.

Census data are adjusted to take into account net census undercoverage and incompletely enumerated Indian reserves. Components of population change occurring between census day and July 1, 1991 or 1996 were also taken into account.

Method for deriving demographic estimates by health regions

Population estimates at the census division (CD) level are produced annually by Demography Division, using the component method, which accounts for changes in the number of births and deaths, as well as intraprovincial, interprovincial and international migration. The CD population estimates are prorated to the provincial population estimates.

Demographic estimates by health region are derived from these estimates using the following steps:

Calculation of conversion factors:
Health Statistics Division has created a file linking enumeration areas (EAs), census subdivisions (CSDs) and census divisions (CDs) for each health region.

The 1996 Census population by CDs (EAs or CSDs in case of split CDs) was adjusted for late changes in geography and for partially enumerated Indian reserves to ensure EAs added up to the CD.

In cases where health regions split CDs, the proportion of population in each CD split is used to derive 'conversion factors' in order to allocate the CD level estimate to the appropriate health region.

Application of conversion factors to CD demographic estimates:
Conversion factors were applied to CD population estimates for 1995 to 1997 allowing conversion of CD population estimates into HR population estimates. The same approach used to obtain the total population estimates was used to establish age and sex estimates by HR.

For more information on health region level estimates, please refer to Health Regions - 2000 CD-ROM, Statistics Canada, Catalogue no. 82F0082XCB.

Provincial methodologies

For health regions in Quebec and British Columbia, the administrative files used for adjusting the 1996-based population estimates for non-census years differ from those used by Statistics Canada in the description above. For these two provinces, the health region population estimates were supplied by the Institut de la statistique du Qu�bec and BC Stats.

Quebec
For information on the methodology used to derive the health region population estimates in Quebec, for 1995 to 1997, contact the Institut de la statistique du Qu�bec, Direction des statistiques sociod�mographiques at (418) 691-2406 or e-mail demographie@stat.gouv.qc.ca .

British Columbia
The methodology used by British Columbia to derive small area populations by gender and age group is divided into two parts.

A Regression Approach, specifically the Difference-Correlation Method (DCM), is the primary method underlying the sub-provincial population estimates. A secondary method, known as Proportional Allocation (PA), is also used to estimate the population for certain classes of areas. Both these methods use information derived from a set of indicators obtained from administrative files that are symptomatic of regional population changes.

In essence, the British Columbia small area population estimation model works as follows. Beginning with the most recent federal census (in this case the 1996 Census of Canada), each region's share of provincial population is adjusted up or down according to the current share of the provincial total of a weighted combination of residential hydro connections and/or Old Age Security recipients. Estimates of the population living in municipalities along with that portion of the population living outside the municipality but within the regional district (i.e., unorganized area), are controlled at the provincial level by a British Columbia population estimate prepared by Statistics Canada. Regional district population estimates are derived by summing the municipal and unorganized area population estimates. Local health areas are also controlled at the provincial level, and in order to ensure consistency, the local health area population estimates within each regional district are then tied to the regional district population estimates.²

¹ The population estimates for health regions in Alberta prepared by Statistics Canada differ from those of Alberta Health and Wellness which are based principally on Alberta's health care file. The differences in these estimates are shown in Appendix 2. Work is under way to try to reconcile these differences.

² BC Stats. Generalized Estimation System (GES), Small Area Population Estimation Methodology. Ministry of Finance and Corporate Relations, December 1998.
Detailed information about the methodology used for estimating the age/gender distribution of small area population in British Columbia can be found in two documents on the BC Stats website www.bcstats.gov.bc.ca "Generalized Estimation System (GES)", December 1998, and "Estimating the Age/Gender Distribution of Small Area Populations in British Columbia", April 1994.