ABSTRACT

The computation of life tables is one of the oldest techniques in demography. The only natural way of introducing the notion of a life table is to follow a birth cohort (or a group of cohorts) through time. The construction of a period life table rests on the derivation of a hypothetical cohort, which is taken through all the ages of life and, at each of the various ages, is subjected to the mortality conditions observed for real cohorts in the year (or group of years) studied. Often the abridged life table is derived from approximate computations based on incomplete and sometimes unstable documentation. Complete life tables have been defined as giving, for example, the number of survivors at successive birthdays. The model life tables describe varying structures of mortality by age, corresponding to different levels of total mortality (defined by the expectation of life at birth).