Combining the reference hypotheses gives the reference scenario A-00-2020, combining the high hypotheses gives the “high” scenario B-00 2020 and combining the low hypotheses gives the “low” scenario C-00-2020.
The reference scenario describes the trend considered, at the time of calculation, to be most plausible for the coming decade. The “high” and “low” scenarios indicate the plausible range of future growth in the resident population and the economically active population.
In addition to these three basic scenarios, two alternative scenarios and seven variant projections were calculated with regard to population change and seven variant projections with regard to the economically active population.
The variants of the reference scenario were established by changing the assumptions for only one component of population change in each case: fertility, mortality and migration. These variants are calculated in order to study the influence of each demographic component on the evolution of the population and on the evolution of the various indicators describing its structure.
The alternative scenarios D-00-2020 "accelerated ageing" and E-00-2020 "attenuated ageing" give a plausible range for the evolution of old-age dependency ratios. The first has the same assumptions as the "low" scenario except for the mortality that corresponds to that of the "high" scenario and the second has the same assumptions as the "high" scenario except for the mortality that corresponds to that of the "low" scenario.