A probability mixture model of completed parity

This research was designed to find a probability model that would adequately describe completed parity for women in populations characterized by high fertility combined with high zero parity. A negative binomial mixture distribution was adapted for this purpose. The form of this distribution suggests the hypothesis that human populations consist of two subgroups of women with respect to completed parity, defined according to whether they do or do not produce viable offspring. Results of the present research further suggest that the proposed distribution for completed parity has general applicability across human populations, whether they are of a high or low fertility type, and whether they have a high or low zero parity.