Wage discrimination exists when workers are equally qualified and perform the same work but one group of workers is paid more than another. Historically, wage discrimination has favored men over similarly qualified women.[4]
Income disparity between genders stems from processes that determine the quality of jobs and earnings associated with jobs.[clarification needed] Earnings associated with jobs will cause income inequality to take form in the placement of individuals into particular jobs through individual qualifications or stereotypical norms.[citation needed] Placement of men or women into particular job categories can be supported through the human capital theories of qualifications of individuals or abilities associated with biological differences in men and women.[citation needed] Conversely, the placement of men or women into separate job categories is argued to be caused by social status groups who desire to keep their position through the placement of those in lower statuses to lower paying positions.[5]
Human capital theories refer to the education, knowledge, training, experience, or skill of a person which makes them potentially valuable to an employer. This has historically been understood as a cause of the gendered wage gap but is no longer a predominant cause as women and men in certain occupations tend to have similar education levels or other credentials. Even when such characteristics of jobs and workers are controlled for, the presence of women within a certain occupation leads to lower wages. This earnings discrimination is considered to be a part of pollution theory. This theory suggests that jobs which are predominated by women offer lower wages than do jobs simply because of the presence of women within the occupation. As women enter an occupation, this reduces the amount of prestige associated with the job and men subsequently leave these occupations. The entering of women into specific occupations suggests that less competent workers have begun to be hired or that the occupation is becoming deskilled. Men are reluctant to enter female-dominated occupations because of this and similarly resist the entrance of women into male-dominated occupations.