The class action suit against Wal-Mart has brought new attention to the issue of sexual discrimination in the workplace. Women typically earn less than men, and this has often been attributed to women having less education and work experience. About half of the wage gap between men and women can be explained by these "observable" factors, however, studies show that anywhere from 10 to 30 percent of the "unobservable" difference in the wage gap is solely a result of gender difference.
See "Discrimination is still a factor in male-female wage gap", Stacey Hirsh, Chicago Tribune, June 29, 2004