This illustrates the crowding model / overcrowding model. This is when crowding into lower wage jobs due to preferences or lack of alternative opportunities. This non-neoclassical model was first established by Bergmann. According to the model, result of the professional segregation is wage differentials between two genders. The explanations for segregation may be socialization, individual decisions, or labor market discrimination. Wage differentials occur when the job openings or demand for the female-dominated sector is less than the supply of women.