Women and men tend to do different work. Women are concentrated in lower-paid sectors and grades, which is called occupational segregation, and they do most of the unpaid care work at home. National income accounts count mainly market activity, so this work is largely invisible in the figures.
The results are a gender pay gap, a 'glass ceiling' that blocks qualified women from top posts, and a 'sticky floor' that holds many in low-paid jobs. A woman with a paid job and the housework carries a double burden.
The UNDP measures these gaps with indices. Each index has its own components, and questions often test which component belongs to which index.