The key problem with the “77 cents on the dollar statistic” cited in President Obama’s SOTU speech is that it is based upon a naive comparison of average earnings for females compared with males. There are a number of other wage determinants (e.g., differences in occupations, positions, education, job tenure, hours worked, etc.) which must also be taken into consideration.  AEI scholar Christine Sommers notes (in the Daily Beast article linked below): “When all.. relevant factors are taken into consideration, the wage gap narrows to about five cents. And no one knows if the five cents is a result of discrimination or some other subtle, hard-to-measure difference between male and female workers.”