Population Control in China: Theory and Applications.

Abstract

Chinas pressing situation of high population growth rates compelled demographers and scientists to develop a model capable of expressing the dynamics of population changes under the countrys planned birth policy thus reflecting the reality of the country. They developed a planned birth model or macro-model of population control consisting of a system of controlled dynamic population equations. This macro-model has been successfully used in Chinas population control program. The book suummarizes those aspects of population control theory that have had direct applications in designing and checking Chinas planned birth program. It includes such topics as population equations with feedback fertility control longterm controlled projections Liapunov stability theory analysis of optimal or feasible population levels and optimization of birth control policy. 2 models are built in this book: one is the continuous model that is a partial differential equation with a boundary-feedback control; and the other is the discrete model that is a difference equation. This is a bilinear system of closed-loop control. Both are sufficiently accurate models to describe Chinas population process. The great advantage of the mathematical models is that population process can be simulated on computers. They provide instruments for population projection and control. Any population control must be based on a theory of stability. For this reason Liapunovs theory of stability is introduced. The theory leads to the use of fertility as the only input of population process. There is a limit in the mean number of children born per woman in the reproductive period. If the observed value of this index persistently exceeds this limit population grows in a manner similar to exponential law. If it is smaller than the limit population declines. When it is equal to this limit total population is eventually a constant. Then the natural increase rate is zero. Both population projections and optimization demonstrate that curbing fertility markedly in the next 20 years is the only measure that can lead China onto the right course of population process. This is the basic reason why the Chinese government is resolute in promoting the single-child family policy.