Finite Approximations in Demography.

Conventions exist for carrying out the arithmetic of population projection, finding the intrinsic rate of natural increase, and other demographic calculations. These are good approximations only for populations which are stationary or increasing very slowly. For rapidly increasing populations, they can be readily improved. The aim of this article is to review present practices and suggest some improvements in finite approximations on population. The improved formulae take account of the way in which the increase shifts the distribution of population within the five-year age group. A number of examples are given of the derivation of corrections to existing formulae.