31.   Yet for all the familiarity of the pay gap, a clear understanding of its cause remains elusive.

32.   -- Reduce by half the pay gap between men and women, largely by toughening enforcement of discrimination laws.

33.   The pay gap is caused by discrimination and because women get steered into lower-paying occupations, the study said.

34.   The pay gap is based on discrimination and women often getting steered into lower-paying occupations, the study said.