Demographic-Effects Assessing Of Chinese Population Fertility Transition

To nearly-closed Chinese population system, the indexes of its population states change or develop inherently and coherently, which logical relations between population changing and fertility changing, mortality changing and other demographic factors are clear and precisely. Thereby, both on quantity changing and age-structure ratios changing of Chinese population, demographic effects or relative influences which caused by fertility changing, mortality and other factors changing are quantified respectively and compared, so did phased-historical population changing. The results can be used to explain how Chinese population had been changing, so did scientific anticipation of future population state's changing.On the analyzing methods of demographic effects, time factor of population changing (such as fertility changing, mortality changing, etc) and population's quantity changing and age-structure changing is divided by two periods, one is analyzing period, the other is future period. It is supposed that fertility will takes the level of replacement fertility, mortality and other factors will not change in future period, and which is also selected for comparative anticipation in studying period. So, based on demographic analyzing method(such as Comparative Anticipation analyzing method) an stable population theory, the procedure of quantifying demographic effects method which is caused by fertility changing or by population changing during history time, are constructed. For logical of analyzing procedure is consistent with Mule's law, and demographic effects is time- serially changing, the results of demographic effects quantifying can be used to make clear the logical relation between fertililty changing,population changing and population states changing wholly and intutivitely.The main of research can be divided by four parts. Firstly, the procedure of demographic effects which is caused by a period of time fertility changing is constructed, so did time-lagged demographic effects which is caused by historical population changing; Secondly, whole Chinese population is selected as studying object, time is separated by three phases, which can be called "before Fertility Transition, "during Fertility Transition" and after Fertility Transition". In further, the period of Chinese Fertility Transition can be separated by "fertility declining fast phase", "fertility changing toward replace level phase", and" low-level fertility phase", demographic effects which is caused by periodic historical population changing or by periodic fertility changing are quantified individually, also be compared in the same time. Thirdly, demographic effects which are caused by different procedure of fertility transition is constructed and compared, one can be used to clarify influence of different fertility changing procedure between county and city on population quantity and age-structure, the other can be used to evaluated Chinese fertility control policy's influence on population changing.In end, the uncertain of future population's anticipation's origin and influence is analyzed.The main of this research can be summarized as follows,Firstly, demographic effects which are caused by historical population changing before Chinese population fertility transition starting, would change with time changing, which have been obligated peak of population quantity and elder ratio level. On population quantity changing, large scale momentum of population changing had been laid aside, which will almost made Chinese future scale, its influence will last until 2027; On age-structure changing, low dependency ratio, low elder dependency ratio during 1982～2027 had been laid aside, with aging procedure be deferred.Secondly, demographic effects which are caused by historical population changing until Chinese fertility transition finished, will have been expanding population size. In linkage with influence of age-structure changing, potential size will exceed stable population quantity during 2015～2075. Meanwhile, population negative increase will be obligated during 2045-2100, potential aging will be deferred until 2050. Accordingly, its time-lagged influences will decrease potential level of elder dependence ratio. Nevertheless, which will increase potential level of aging in last half of 21st century, so does elder dependency ratio. Its time-lagged influences cause dependency ratio fluctuating largely, which also cause demographic dividend be obligated until 2040, demographic debt be obligated during 2040～2065.Thirdly, demographic effects which are caused by population changing during Chinese fertility transition are different from the upper. On population quantity changing, its time serial distributing takes on "one peak", potentially expanding quantity size. However, influence is smaller than before. On age-structure changing, it accelerates potential aging in the last half of 21st century, decreasing the level of elder dependency ratio in the beginning of 21st century. Meanwhile, it will increase potential level henceforth. Accordingly, time-serially distributing of demographic effects on dependence ratios takes on "two peak", demographic dividend in first half of 21st century, demographic debt during2015～2025 will be obligated accordingly.It also shows that the scale of demographic effects caused by fertility factor would be positive relation with fertility level exceeding the replacement's scale, so do fertility changing's time. Comparatively, demographic effects caused by none-fertility factors are evidently different. On population quantity changing, fertility decreasing is main influencing factor. However, on age-structure changing, mortality and other none- fertility factors is main influencing factors, but all time-lagged demographic effects on aging structure changing will die away in a hundred year.Forthly, demographic effects which are caused by fertility changing different procedure between county and city, could made clear of its influence on whole Chinese population state's changing procedure, so did on heterogeneity of Chinese population changing. Demographic effects which are caused by different fertility changing procedure between china and other country are analyzed to provide a useful method to evaluate Chinese fertility policy's influence on population quantity control.Nevertheless, based on further analyzing and comparing on some influential anticipation of future Chinese population which made by different authorities, the uncertainty of the demographic anticipation results and its distribution is evidently disclosed. It shows that quantity, age-structure of future Chinese population, and population states evolving all are uncertain. it can make reasonable explain that spical future population changing circumstance is supposed to consistently analyzing demographic effects.In conclusion, Chinese demographic effects are quantified and compared in the same time, the research results directly show different factors'divergent influences during population station evolving, which also show the order of population changing, so did logical relation between fertility, or mortality and population changing. So, the research has some academic significance. The results can provide scientific demographic evidence to clarify or anticipate population problems, which are closely relative with population states changing. So, Chinese demographic effects analyzing research also has application value in making social policy.