The traditional models of demographic analysis study the growth and development of one sex and ignore the contribution of the other. These one-sex models produce adequate results where the development of an appropriate two-sex model has not been a central issue for demographers. The traditional one-sex models used by demographers are outlined and their limitations are pointed out in handling the necessary interaction between the sexes. Some of the important approaches which have been proposed to tackle the two-sex problem are described.
Pollard, J. H. (1997). Modelling the interaction between the sexes. Mathematical and Computer Modelling, 26(6), 11–24. https://doi.org/10.1016/S0895-7177(97)00166-0