2.2.4 Results for the support ratios
We calculated six sets of projections for the support ratio. The first four sets were obtained by combining the four population variants described above with the base consumption and productivity weights. The remaining two were obtained by combining the base population variant with the alternative variants for consumption and productivity. The various combinations are summarized in Table 4.
| Demographic rates | |||||
|---|---|---|---|---|---|
| Projection | Fertility | Mortality | Migration | Consumption | Productivity |
| Base | Base | Base | Base | Base | Base |
| Low fertility | Alternative | Base | Base | Base | Base |
| Low mortality | Base | Alternative | Base | Base | Base |
| Low migration | Base | Base | Alternative | Base | Base |
| Alternative consumption | Base | Base | Base | Alternative | Base |
| Alternative productivity | Base | Base | Base | Base | Alternative |
Figure 7 presents the results of the calculations. In all cases apart from the low-mortality scenario, the support ratio stops changing towards the end of the projection period, as the condition of population stability (discussed above) is reached. Predictably, the support ratio falls furthest in the low-fertility and low-mortality cases. It is worth noticing, however, that the support ratio is initially higher in the low-fertility case than in the base case. The reason can be identified in Figure 5. In the low-fertility case, the proportion of the population aged 0-19 falls sharply from the very beginning of the projection, which pushes the support ratio upwards. This effect is eventually counteracted by the rise in the proportion aged 65 and over, but there is a delay of several decades before the rise in the population aged 65 and over occurs. Comparison of the base and alternative consumption projections shows the effects of using different consumption weightings: the support ratio falls further in the base case than in the alternative case because the Jensen equivalence scale gives a higher relative weight to the consumption of older adults than the Guest and McDonald scale. Much the same is true for the alternative productivity weights. The support ratio falls further in the base case than in the alternative case because older adults are more productive, relative to younger adults, in the alternative case.
