A population projection scenario is obtained by combining assumptions on how each component of population growth will evolve in the future. Text table 2.1 summarizes the assumptions made for each of the components.

When three assumptions on fertility, mortality and international immigration and four assumptions on interprovincial migration are combined, 108 different scenarios can be generated, which is much too large a number for all the scenarios to be relevant and described here. Of this set of 108 combinations, we have chosen six that offer a range of possibilities among the scenarios that generate high and low population growth for the provinces and territories.

This choice results from a number of considerations, including:

1. offering a high-growth scenario and a low-growth scenario that should together provide, at the national level, a range of projected numbers that is sufficiently wide to represent the uncertainty inherent in this analysis;
2. taking account of the fact that of all the components of population growth, the most volatile and difficult to project is interprovincial migration;
3. taking account of the fact that while long-term projections are useful for various purposes, the scenarios published should emphasize the short and medium terms, since projections are updated regularly.

Text table 2.1
Assumptions of fertility, mortality, immigration, emigration, non-permanent residents and interprovincial migration

Text table 2.2
Summary table presenting underlying assumptions to the six selected scenarios

The synoptic table describes the six scenarios selected (Text table 2.2 ). Scenarios 1 and 6 combine the low and high assumptions on fertility, mortality and immigration so as to produce respectively the lowest and the highest growth levels at the national level, thus meeting the first of the above selection criteria. The medium interprovincial migration assumption is associated with these two scenarios.

The medium assumptions on fertility, mortality and immigration are combined with the four assumptions on interprovincial migration to form scenarios 2 to 5. During the past 30 years, fertility has changed little from one year to the next, while the upward trend in life expectancy is almost linear. Immigration levels have been relatively high since 1990 and the most recent immigration plan of Citizenship and Immigration Canada slightly raises immigration objectives (between 225,000 and 255,000 in 2006) compared to the previous three years. The middle assumption of each of these components is based on this recent past. We thus meet the second and third criteria set out above by associating each of the four interprovincial migration assumptions with the medium assumptions on how the other components will evolve.