responsible for these wage differences, then evidence that this characteristic is more important for men than for women would bolster one's case. This inquiry fits into an extensive literature on the role of segregation in generating racial, ethnic, and sex differences in labor markets, but takes this literature in a new direction. In the literature on sex differences in wages, considerable attention has focused on the role of occupational segregation, in particular the concentration of women in low-wage occupations (e.g., Johnson and Solon, 1986; Sorensen, 1989; Macpherson and Hirsch, 1995). However, relatively little attention has been paid to the role of occupational segregation in generating racial and ethnic differences in wages (for an exception, see Sorensen, 1989), in part because occupational segregation between races and ethnic groups is much less pronounced than occupational segregation between the sexes (King, 1992; Watts, 1995). Furthermore, even less attention has been paid to the role of segregation along other dimensions such as industry, employer, and job cell (occupation within employer). The main reason for the lack of such work is that the data sets labor economists typically use to study wage differences are household data sets, which allow one to measure the percent female or black in an occupation or industry, but not the sex, race, or ethnic composition of firms, establishments or jobs. Economists interested in studying these other dimensions of segregation have had to turn to other special data sources in which information on the workforce is available or can be constructed. For example, Groshen (1991) uses data from the Bureau of Labor Statistics Industry Wage Surveys, with which one can measure the percent female by establishment as well as job cell. Blau (1977) studies BLS Area Wage Surveys, which cover clerical, professional, and technical occupations, and which allow the estimation of percent female along ...
