Projections: of Population Growth

The projections use a "cohort-survival" method, the most commonly used approach for developing long-term projections of population. The model employs the following steps:

1. Starting in the base year of the analysis, data are obtained on population by single year of age, by sex. In this case, the data are for July 1, 2001. The database can be drawn either from the 2001 census, or from Statistics Canada's post-censal estimates. The main difference between these two data sets is that the census data do not include 100 percent of the population, as some people are missed by the census (and some people are counted more than once) whereas the post-censal estimates are adjusted for "net under-coverage" and are presumed to count 100 percent of the population.* In the 2001 census data, the population for the GGH is estimated at 7.53 million; in the 2001 inter-censal estimates, the population is 4.6 percent larger, or 7.88 million.
2. The annual number of births is estimated by applying fertility rates to the estimates of the female population (by age group) at the start of each year. The rates used were the 2001 fertility rates for Ontario, as estimated by Statistics Canada. For each Census Division, the division of the births between males and females is based on the actual male-female shares of the newborn population in the Census Division as of 2001.
3. Each year, as the population ages by one year, each age group is moved up to the next bracket. In the process, "survival rates" (the percentage of people in each age-sex group who are still alive one year later) are applied, to account for deaths. Survival rates are derived from Statistics Canada data for Ontario as of 1995-1997.
4. Adjustments are made for migration -- adding the projected number of immigrants, subtracting the projected number of emigrants, and adding (or subtracting) net interprovincial and net intraprovincial migration. In Section 3 of this report, a method was developed for projecting each of these components of migration, and a summary table showed factors for each of the components, for three aggregated areas: the Inner Ring, Outer Ring, and GGH. In developing the following projections, the sets of factors were projected individually for each of the 16 Census Divisions in the study area. The migration components have been measured and projected in the following way:

• Immigration is the percentage of Canada's immigrants who move into the Census Division each year. The Hemson report (page 20) assumes that immigration to Canada will average 218,000 people per year during 2001 to 2006, and just under 210,000 for the remainder of the projection period. The same assumptions are used here. After total migration is estimated for each Census Division, the migrants are distributed by age and sex using the actual distribution (for the respective Census Divisions) for immigrants who arrived from 2001 to 2003. The assumption that the level of immigration will be stable for a 25-year period is quite strong. For example, in fall 2005, the federal government started to argue for increased immigration targets. It has been suggested that annual immigration could be as high as one percent of Canada's population, which would result in annual figures of more than 300,000.
• Emigration is expressed as a percentage: the number of net emigrants from the Census Division divided by its population at the start of the year. Given the lack of data for analysis, it has been assumed that for each Census Division, the rate is equal to the average seen over the 1997-to-2004 period. The age-sex distribution is based on the actual distribution (for the respective Census Divisions) of emigrants from 2001 to 2003.
• Net interprovincial migration is expressed as a percentage: net interprovincial migration to or from the Census Division, divided by the population of Canada excluding Ontario at the start of the year. Long-term population projections are needed for Ontario and Canada. The projections used here are from Statistics Canada, "Projection 2: medium-growth and medium inter-provincial." These projections cover the 2001-to-2026 period. The projections have been extended to 2031 in this analysis. In applying the projections of net migration, the age-sex distribution is based on the actual distribution (for the respective Census Divisions) of interprovincial in-migrants in 2001-2003.
• Net intraprovincial migration is expressed as a percentage: net intraprovincial migration to (or from) the Census Division divided by the population of Ontario at the start of the year. The age-sex distribution is based on the actual distribution (for the respective Census Divisions) of net intraprovincial in-migrants in 2001-2002.
• This process was followed for each year of the 2001-to-2031 projection -period.

Source: Will Dunning Inc.

Over the 30 years, the projections indicate a shift in the shares of population and population growth:

• In 2001, the Inner Ring had about 74.1 percent of the GGH population, and the Outer Ring had about 25.9 percent.
• During 2001-2011, the Inner Ring receives 69.6 percent of the GGH's population growth. In 2011-2021, the Inner Ring's share of growth falls to 65.7 percent. During 2021-2031, the Inner Ring share of growth falls again to 61.2 percent. Over the entire period, the Inner Ring is projected to receive 66.3 percent of the GGH population growth and the Outer Ring 33.7 percent.
• By 2031, the Inner Ring's share of the GGH population is projected to be 72.1 percent, versus 74.1 percent in 2001.

Table 12: Actual and Projected Population by Area, 2001 to 2031

Notes

* The projections performed by Hemson in its Growth Outlook for the Greater Golden Horseshoe used the census data and a similar cohort-survival model. At the end of the exercise, the Hemson model added an adjustment for under-coverage. In all likelihood, the Hemson approach would generate results similar to those developed in this report, if similar assumptions were used for the key input variables.