In India, China and sub-Saharan Africa, millions upon millions of women are missing. They are not lost, but dead: victims of violence, discrimination and neglect.

A University of British Columbia economist is amongst those trying to find them – not the women themselves, who are long gone, but their numbers and ages, which paint a sad and startling picture of gender discrimination in the developing world.

The term "missing women" was coined in 1990, when Indian economist Amartya Sen calculated a shocking figure. In parts of Asia and Africa, he wrote in The New York Review of Books, 100 million women who should be alive are not, because of unequal access to medical care, food and social services. These are excess deaths: women "missing" above and beyond natural mortality rates, compared to their male counterparts.

Women who are dead because their lives were undervalued.