The Gini coefficient is a standard measure of income inequality. (D.C. Office of the Chief Financial Officer)

Economists for the District’s Office of the Chief Financial Officer have taken a look at D.C.’s level of income inequality over time.

They calculated the city’s yearly Gini coefficient — a standard measure of inequality that has driven much discussion about income disparities in the District and around the world — and data released Wednesday show that the District has a level of inequality that not only distinguishes it among the 50 states but also the globe.

In 2010, the most recent year for which a significant body of global data is available, D.C.’s Gini index stood at 61.4, according to the CFO economists. According to World Bank data, none of the 66 countries reporting data had a higher Gini number — not Namibia (61.3), not Colombia (55.5), not China (42.1) and not the United States as a whole (41.1).

Caveats abound here, starting with the general inadvisedness of comparing a large city, with its mix of very rich and very poor, to a U.S. state or a nation. And the Gini index itself has been criticized as a blunt instrument to measure a nuanced phenomenon. But there is evidence that the District’s performance is notable among global cities. A 2008 United Nations report concluded that major American cities “such as Atlanta, New Orleans, Washington D.C., Miami, and New York, have the highest levels of inequality in the country, similar to those of Abidjan, Nairobi, Buenos Aires, and Santiago.” A Gini of 60 or more puts D.C. above the average seen in selected cities of Latin America and the Caribbean (0.55), Africa (0.54) and Asia (0.4) in the past decade — though well below the 70-plus Gini figures seen in some South African cities.

The new data reinforce the notion that the city’s 15-year cycle of economic growth has resulted in increasing inequality. An analysis shows a relatively close correlation between the Gini index and the performance of the stock market — indicating that when the economy is weaker, inequality declines somewhat. But note that the trough seen following the 2008 economic crisis saw higher Gini levels than in the previous economic slowdown, following the 9/11 attacks — even though the former was considered to be much more severe for the local, national and global economy.

The Gini coefficient is a standard measure of income inequality. (D.C. Office of the Chief Financial Officer)