The Hoover Index is a number used to measure how unequal a group's wealth is. It's named after the US president Herbert Hoover, who was president during the Great Depression in the 1930s.
To figure out how uneven the wealth is in a group, you would look at how much money the wealthiest person has compared to how much money the poorest person has. For example, let's say the wealthiest person has $1,000 and the poorest person has $100. That's a huge difference - the wealthy person has ten times as much money as the poorest person. That means the wealth in the group is really uneven - the wealthiest person has most of the money.
So in this example, the Hoover Index would be 10, because the wealthiest person has ten times more money than the poorest person. A higher Hoover Index number means the group's wealth is more uneven. The higher the Hoover Index number, the more unequal the group's wealth is.