"Point four three. Point five three. Point five six!" It's not every day that you get to write a lede this juicy.
But in an election year where who's making how much money is making serious headlines, the story behind 0.43, 0.53, 0.56, and 8 other numbers just like them, cut to the very heart of Vermont Senator Bernie Sanders' argument for becoming the next Cranky Ol' Commander and Chief of these United States.
Bernie's Favorite Numbers: The Gini Index quantifies income inequality. I mapped it since 1820! What do you think the trend is? Hmmmm?
These 11 numbers -- which you can explore live here -- are numeric royalty. They're part of the Gini Index, a single-number score for just how effing bad society is at dividing its riches. The Gini Index is the brainchild of turn-of-the-20th-century Italian sociologist and numbers-nerd Corrado Gini. Who back in 1912, rocked the numeric world by developing a score of how the rich dick over the poor.
I Dream of Gini: Italian sociologist Corrado Gini is the eh ... "Prince" of social scientists.
The Gini Index is rock-star numeric stuff: The World Bank uses the Gini Index. The CIA uses the Gini Index. Mathworld even uses the Gini Index. And I see why: The Gini score packs big meaning into just a few numbers. And in these days where terabytes of data can be worse than meaningless, it is positively thrilling to be reminded that exactly 11 numbers, if they are the right numbers, can teach anybody about the rich and the poor -- over the past two hundred years!
If only Mr. Gini had founded Google, who knows how lean and mean the Web would have turned out to be.
Gini's Index in Action: Each ten-out-of-hundred get a given share of society's wealth. The steeper the curve, the more unequal the wealth. Where do you think you live? Chart by Clear Lines Consulting.
Here's how the Gini Index works: Each group of 10 people out-of-a-100 in society is ranked from right to left in the chart above. And the share of society's wealth each gets is ranked from top to bottom. I dug this Gini Index chart from the kind folks at Clear Lines Consulting, a San Francisco-based analytics firm. The straight blue line is the theoretical county of Equalistan, where wealth is divided evenly across all 10 groups. The top 10 out-of-every-100 people may be richer than the bottom 9, but not proportionally so. See the idea? Everything is equal. What happens if the top 10 percent sneak in more than average say, 15 cents of every dollar of wealth? That leaves the bottom 10 people out of 100 with only 5 cents of every dollar. And the curve sags down to the red line now graphed as Similaristan. Here wealth distribution is essentially similar across all groups. But not equal. Pretty cool!
But, and this is a big but, if the top 10 out of a 100 get a full 90 cents of every dollar of society's wealth, what happens? We are all shivering away in a country called Slaveristan, where the top 10 out of a 100 people make 90 cents out of every dollar society makes. Or pretty much what the United States of America looks like these days if you believe Bernie Sanders' "ten percent take-all" argument.
A World Bank data nerd named Branko Milanovic took Gini's work and retrofited it back to 1820, with this WikiPedia post. That's the chart I created above that shows the relative progress of income inequality over the past few centuries.
If these 11 numbers are even half-correct, is it any wonder a political nobody from Vermont came to dominate the debate on how the world splits its wealth? Agree or disagree with Bernie Sanders, but Mr. Gini, and his ratio show why this man has the shaped national debate.
90 people out of a 100 have no other choice but to feel the "Bern."