If you want to talk about income inequality, chances are you’ll use the Gini Coefficient, a one-number measurement that is so ubiquitous we’ve forgotten its history. Here’s a long story I did for Pacific Standard about the history of social science’s most influential metric, and how it became a pop phenomenon.
It’s been so useful, so adaptable, that its strange history has survived only as a footnote: the coefficient was developed in 1912 by Corrado Gini, an Italian sociologist and statistician—who also wrote a paper called “The Scientific Basis of Fascism.” After running Italy’s Central Institute of Statistics under Mussolini, Gini eventually had a falling-out with the fascist state, but he remained a control freak to the end of his life. In the 1950s, at his own statistics institute in Rome, he made his professors and assistants work “in small glass boxes, fitted with a microphone which Gini could use to listen and talk, but the occupier of the box could only reply if spoken to,” according to a professor who worked there. To Gini, statistics—including his famous coefficient—were a way for states to see beyond the “noise” of individual feelings and agendas, channeling human and material resources to become more powerful.
And yet, nearing its 100th birthday, the Gini Index became part of the noise in the streets. When crowds at Occupy Wall Street events shouted “We are the 99 percent,” the media reached for the Gini to explain and evaluate the broad narrative of inequality.