ABSTRACT

Together with extending length of people's life, more precise identification of regularities in mortality of the aged becomes more and more important. More often, so called fourth age group (besides children, adults, elderly people) is singled out – the aged, that is people at the age of over 80 years. This caesura of age is accepted not only in demography, but also in researches within the scope of biology, gerontology and others. Changes in the age structure and intense ageing of population in different regions of the world brings with it significant consequences of social and economic kind. Therefore, there is nothing surprising in the fact of heightened interest in mortality of people in this age group, and hence in the possibilities of modelling proper functions describing the living pattern for those people. Adapting models describing length of human life for the aged leads most frequently to overestimation of mortality, because over certain age there is a noticeable decrease in the rate of growth of probability of death among the aged. Accepting such an assumption, of a decrease in the rate of growth of probability of death among the aged, is connected with selection intensifying with age, which causes that up to the old age live people of the best health. Changes are also visible in the relation between endo- and exogenous factors of deaths, that is „risk of the background – environment” and risk connected with the processes of ageing of an individual.