Mortality risk assessment through stationary space-time covariance functions

Dynamic life tables arise as an alternative to the standard (static) life tables with the aim of incorporating the evolution of mortality over time. These tables can be considered as a two-way table on a grid equally spaced in either the vertical (age) or horizontal (year) directions, and the data can be decomposed into a deterministic large-scale variation (trend) plus a stochastic small-scale variation (residuals). In this context, space-time geostatistical methods can be used for fitting and predicting the dynamic mortality. We use four different space-time covariance functions for fitting and predicting mortality in Spain during the period 1980-2005. In particular, we aim at showing the behavior of separable versus nonseparable fitted structures on one hand, and the behavior of simple structures given by combinations of products and sums versus more complicated negative structures on the other hand.