By Chris Giles in London
Economist and author Thomas Piketty
Thomas Piketty’s book, ‘Capital in the Twenty-First Century’, has been the publishing sensation of the year. Its thesis of rising inequality tapped into the zeitgeist and electrified the post-financial crisis public policy debate.
The data underpinning Professor Piketty’s 577-page tome, which has dominated best-seller lists in recent weeks, contain a series of errors that skew his findings. The FT found mistakes and unexplained entries in his spreadsheets, similar to those which last year undermined the work on public debt and growth of Carmen Reinhart and Kenneth Rogoff.
The central theme of Prof Piketty’s work is that wealth inequalities are heading back up to levels last seen before the first world war. The investigation undercuts this claim, indicating there is little evidence in Prof Piketty’s original sources to bear out the thesis that an increasing share of total wealth is held by the richest few.
Prof Piketty, 43, provides detailed sourcing for his estimates of wealth inequality in Europe and the US over the past 200 years. In his spreadsheets, however, there are transcription errors from the original sources and incorrect formulas. It also appears that some of the data are cherry-picked or constructed without an original source.
Contacted by the FT, Prof Piketty said he had used “a very diverse and heterogeneous set of data sources ... [on which] one needs to make a number of adjustments to the raw data sources.
“I have no doubt that my historical data series can be improved and will be improved in the future ... but I would be very surprised if any of the substantive conclusion about the long-run evolution of wealth distributions was much affected by these improvements,” he said.
His contention to have found a “central contradiction of capitalism” has in recent months made him a hero of the left. Although his conclusions have stirred controversy, there has, until now, been near unanimous praise for the quality of his statistical work.
On a tour of the US last month, Prof Piketty met Jacob Lew, US Treasury secretary, gave a presentation to the White House Council of Economic Advisers and lectured at the International Monetary Fund and the UN.
Professor Joseph Stiglitz of Columbia University said Prof Piketty’s “fundamental contribution” was the provision of data on the distribution of wealth. It was the subject of laudatory reviews in the Financial Times and other publications.
In Britain, Ed Miliband, Labour leader, told the Evening Standard: “I’m in the early stages of the book. In a way, he is symptomatic of what people are actually feeling”.
In his response to the FT, Prof Piketty said that more recent data not in his work showed “the rise in top wealth shares in the US in recent decades has been even larger than what I show in my book”.