rivista italiana di economia demografia e statistica - Sieds

Rivista Italiana di Economia Demografia e Statistica
changes concavity, K is a parameter governing the steepness of at age H,
and G is the value of in H.
For all of the Australian mortality datasets, rates graduated by (3) are almost
identical to those obtained by model (2) and so are the reported scores (see
Table 1). Mortality rates for the Valencian dataset, graduated using both models,
are displayed in Figure 1; model (3) seems to adapt better than model (2) at older
ages. But there is also an improvement at those ages that more feel the effects of
accidental mortality; this is due to the additive nature of (1). The better fit of (3)
over (2) is confirmed by a 26% lower score.
Figure 1 – Graduation of mortality data for the Valencia Region (1999-2001) using model
(3) (solid line) and model (2) (broken line). The observed qx values are indicated by dots.
log(q x)
-7 -6 -5 -4 -3 -2 -1 0
0 20 40 60 80
Our second model is an “augmented” version of model (2); it contains a new
parameter R that controls the peakness of the second component and so provides
further flexibility in fitting the accidental bump
x
7