Demographic relationships between generations and models derived from them

Lotkas model represents a dynamic process of population renewal. It links fertility survival and age structure. Some statisticians suggest an intergenerational model that links fertility survival and relationships between cohorts without the stable populations required for the Lotka model. This intergenerational model combines the concept of descendants or reproduction rate with the average generation. The average generation allows researchers to link a mother cohort with a balance of daughter cohorts. One can thus retrace mother cohorts from daughter cohorts and daughter cohorts from mother cohorts. This model will find several uses in demographic theory imperfect statistics in retroprojection and in historical demography. It covers the expanse of time in two directions in a coherent and a symmetrical fashion. It integrates longitudinal vision and transverse vision of demographic phenomena. The basis of this model is the ancestor-descendant relationship or the relationship between mother cohorts and daughter cohorts. In effect it approaches real life relationships between the ages while going backward or forward in the course of time.