A new study using satellite data finds that 58% of the global population has been assigned to the wrong tier in the UN's Human Development Index. That can have real-world consequences for how aid reaches people.
On paper, Arcelia looks like a poor-but-average Mexican town. It sits in Guerrero, Mexico's second-poorest state.
Official data gives it a score of 0.714 — firmly in the "high development" band on the United Nations' Human Development Index (HDI).
Then a satellite looks at Arcelia. Using artificial intelligence to analyze what it sees, it returns a lower score of 0.617.
By the UN's own classification, that is no longer high but medium development — a different development tier and a different policy-reality for 33,000 people.
