According to Easterlin, a comprehensive economic framework incorporating the main concepts of demography, sociology and other sciences would be useful to analyse human fertility behaviour in a systematic manner.
Such a framework, it was thought, should be relevant to present and past fertility behaviour in a large number of societies and it should also deal with the trends, fluctuations and differentials observed in fertility during the course of human history.
Keeping these considerations in mind, Easterlin has proposed a framework in which an attempt has been made to combine sociology and economics of human fertility.
As parents are more concerned about the number of grown-up living children rather than the number of births, the principal dependent variable in Easterlin’s theory is the total number of surviving children. It is also assumed that both spouses would live throughout the reproductive span of the wife.