Could it be that the 9% differential are the result of the many factors not considered, for example, these from the book, Why Men Earn More:
- Women who work "full time" work fewer hours than do men.
- When women make the choice to have children are more likely to spend it with their kids than, for example, flying across the country for a conference, let alone a promotion. Indeed, salary studies of the unmarried find that women, for the same work, earn more than men.
- Even within the same job title, the person with more technical skills is more likely to be given a higher salary, since technical skills are more rarely held. Men are more likely to develop technical expertise.