Constructing an Intercensal Mortality-Net Migration Increment-Decrement Table

Abstract

Even in the case that the population census is taken quite regularly, for instance, at a 5-year interval, the life table related to the census is usually prepared for a period of one year or more centering around the census date. Such a life table, however, cannot be conveniently used for analyzing the intercensal population changes. The usual intention of preparing the life table is to study mortality and longevity rather than to use for analyzing the intercensal population changes. This paper aims at constructing a certain type of double increment-decrement table which will be suited to analyze intercensal mortality and migration experiences. Use was made of the two successive population censuses at a five-year interval from 1970 to 1975 for Kyoto city. The basic techniques are as follows. Data are used on the populations at the both censuses by sex and single years of age, annual deaths by sex and single years age, infant deaths by sex and months of age, and births by sex. On the basis of these data, the number of deaths and net-migration volume for each census cohort are estimated on an annual basis, which are then compiled into cross-sectional figures of deaths and net-migration by single years of age for the intercensal period. These steps produce independent mortality and net-migration tables, for the intercensal period, which can be then converted to interdependent tables. The survival ratios computed by _5L_<x+5>/_5L_x from the interdependent tables have been found to generally fit good the actual census survival ratios.