nal sex segregation by sex, researchers usually distinguish labor supply and labor demand factors. Factors related to labor supply generally focus on why women "prefer" certain types of occupation for example, women may "prefer" those with flexible hours in order to allow time for child care, and may also "prefer" occupations which are relatively easy to interrupt for a period of time to bear or rear children. Explanations related to labor demand focus on why employers generally "prefer" to hire women or men for particular occupations and why women and men have different opportunities for promotion and career development within firms.Institutional and labor market segmentation theories are another explanation for why women and men do not work in the same types of jobs. Institutional theories begin with the assumption that labor markets are segmented in certain ways. The best known is dual labor market theory, which distinguishes between a "primary" and a "secondary" sector (Piore, 1971). Jobs in the primary sector are relatively good in terms of pay, security, and opportunities for advancement and working conditions. Secondary sector jobs tend to be relatively poor as regards pay, chances for promotion and working conditions, and to provide little protection or job security. In addition to the duel labor market theory, there is the statistical discrimination theory. This is based on the assumption that there are differences, on average, in the productivity, skills, experience, etc., of distinct groups of workers (such as men and women), and high search and information costs associated with recruitment and promotion decisions. Statistical discrimination theory thus provides an explanation for how some occupations are almost entirely male even though many individual women have greater ability, more education, etc. than many individual men, for example The segmentation of occupations on the basis of workers' sex is thus an important labor ...
