A CAPITAL ERROR: You may remember the fuss over income inequality a few years ago caused by the release of Thomas Piketty’s book Capital in the Twenty-First Century, the bestseller no-one read. it turns out that yet another paper has found problems with Piketty’s data:

I conclude that Piketty’s data for the wealth share of the top 10 percent for the period 1870 to 1970 are unreliable. The values he reported are manufactured from the observations for the top 1 percent inflated by a constant 36 percentage points. Piketty’s data for the top 1 percent of the distribution for the nineteenth century (1810–1910) are also unreliable. They are based on a single mid-century observation that provides no guidance about the antebellum trend and only tenuous information about the trend in inequality during the Gilded Age. The values Piketty reported for the twentieth century (1910–2010) are based on more solid ground, but have the disadvantage of muting the marked rise of inequality during the Roaring Twenties and the decline associated with the Great Depression.

Phil Magness and Robert Murphy, who first drew attention to these errors, are vindicated once again.