The wage gap, by definition, is the difference in income between two groups of people. The term has come to be associated in practice with the difference in pay between women and men. The 1963 Equal Pay Act makes it illegal for employers to discriminate between men and women by giving different pay for the same job.

The EPA has not done a remarkable job in guaranteeing the enforcement of this law. The U.S. Bureau of Labor Statistics reported when the law was passed that men out-earned women 100:58. That ratio now stands at 100:77, showing little difference in more than four decades.

Employers use a number of arguments for why women make less, including lesser education, experience, and productivity. Using these legal criteria for pay differences, employers are able to explain away any difference as one based on the employee’s performance rather than her gender.

Some experts agree with this assessment. Denise Venable, then a research assistant at the National Center for Policy Analysis, wrote an article in 2002 explaining that women’s lifestyle choices, including their decision to take maternity leave, and career choices create a wage gap. Venable argues that the wage gap is a myth.

Other scholars, such as those with the Institute for Women’s Policy Research, tell another story. The IWPR focuses on information released by the U.S Census Bureau in 2004. This information shows a stagnant wage gap in which women and men, when compared to people in their field with the same education and experience level, earn significantly different incomes.

The argument over the wage gap is one likely to continue for some time. Longitudinal studies of the issue showing a continuing trend of inexplicable income differences. Others argue these reasons must exist for some reason beyond gender. Here are some highlights of research available and releases from the U.S. government.

• Female pharmacists have the highest median income of women in any occupation, according to the U.S. Department of Labor.

• The gap is smaller among younger women.

• African American women and Latinas perform the worst in these comparisons. According to the study, African American women may earn only 60 percent of their white male counterparts.

• The Equal Pay Act is virtually unenforceable. Despite its passage, companies continue to pay less money to women. No study exists that shows no wage gap; the difference between studies is the amount of the gap.

• As the stature of profession increases, women’s pay comparable to their male counterparts goes down. The highest discrepancy exists among physicians.

• Education does not reduce the wage gap.