According to Ariane Hegewisch, a study director at the Institute for Women’s Policy Research, pay gaps between men and women are often wider in traditionally high-paying occupations. Six of the 10 occupations with the widest pay gaps had median weekly earnings of more than $1,100, and were all among the higher weekly earnings figures.

These relatively high-paying jobs tend to have much more flexible pay packages that can include such extra incomes as commissions, bonuses, and merit pay. These advantages frequently favor males over females. Six of the 10 occupations had commission-based pay structures, available bonuses, merit-based pay such as tips, or a combination of the three.

These extra earnings are most common in financial occupations. Personal financial advisors, financial services sales agents, and financial managers all had among the 10 worst pay gaps, as well as relatively high median weekly earnings for men and women. The more forms of extra earnings available, Hegewisch explained, “the more scope there is for bias and discrimination.”

How well-represented females are in a particular occupation’s workforce is also a factor contributing to the pay gap. The occupations with the smallest pay gaps tend to have higher proportions of female workers. Alternatively, in six of the 10 occupations with the worst pay gaps, females were a minority of the workforce in 2014.

Hegewisch explained that men working in occupations with fewer men experience less discrimination than women working in male-dominated fields. Discrimination can take several forms. For example, it can be direct when a person is treated differently based on a personal characteristic protected by law. Discrimination can occur indirectly, when a practice or condition is implemented that will have the effect of illegitimate discrimination.

The gender composition of the workforce has changed over the last several decades, but the demands of both career and motherhood remain the same. Jobs such as doctors pay women less in part because women often choose specialties that require fewer hours and can accommodate family responsibilities. For example surgeons, who can “work 80-hour weeks, or 14 hours in a stretch” and receive more money as a result, are disproportionately men, Hegewisch said.