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.
For example, once the FT cleaned up and simplified the data, the European numbers do not show any tendency towards rising wealth inequality after 1970. An independent specialist in measuring inequality shared the FT’s concerns.
Let me first say that the reason why I put all excel files on line, including all the detailed excel formulas about data constructions and adjustments, is precisely because I want to promote an open and transparent debate about these important and sensitive measurement issues (if there was anything to hide, any “fat finger problem”, why would I put everything on line?).
Let me also say that I certainly agree that available data sources on wealth are much less systematic than for income. In fact, one of the main reasons why I am in favor of wealth taxation and automatic exchange of bank information is that this would be a way to develop more financial transparency and more reliable sources of information on wealth dynamics (even if the tax was charged at very low rates, which you might agree with).
For the time being, we have to do with what we have, that is, a very diverse and heterogeneous set of data sources on wealth: historical inheritance declarations and estate tax statistics, scarce property and wealth tax data, and household surveys with self-reported data on wealth (with typically a lot of under-reporting at the top). As I make clear in the book, in the on-line appendix, and in the many technical papers I have published on this topic, one needs to make a number of adjustments to the raw data sources so as to make them more homogenous over time and across countries. I have tried in the context of this book to make the most justified choices and arbitrages about data sources and adjustments. I have no doubt that my historical data series can be improved and will be improved in the future (this is why I put everything on line).
The charges are devastating, and there is plenty to back them up. And again, let’s be abundantly clear: The Financial Times is accusing Thomas Piketty of dishonesty, of making up his arguments, of actively trying to mislead readers and actively trying to mischaracterize inequality trends. This mischaracterization leads to policy prescriptions on Piketty’s part that are both entirely unrealistic in their design and implementation, and, more importantly, are wholly unsupported by the actual data on inequality. The main thrust of Thomas Piketty’s book is entirely undermined, and his arguments and conclusions are annihilated. It is hard to imagine a more comprehensive refutation.
Having established that Piketty’s conclusions are shredded and unbelievable, it is important now to note two things. The first is that the Financial Times–and Chris Giles and Ferdinando Giugliano in particular–deserve kudos for the scholarship and for shining a light on Piketty’s mistakes and dishonesty. For those who are wondering how journalism ought to be done, look no further than the example set down by Giles, Giugliano and the Financial Times in general. They have truly done excellent work. Would that more media outlets followed the example that Giles, Giugliano and the Financial Times have set.
The second thing we ought to note is that neither Giles, nor Giugliano, nor the Financial Times would have discovered that Piketty’s books is fundamentally flawed if they listened to Paul Krugman, who famously said on his blog that “if you think you’ve found an obvious hole, empirical or logical, in Piketty, you’re very probably wrong. He’s done his homework!” Yes, that was a real statement by Paul Krugman, and yes, it ought to haunt him for the rest of his life–and beyond. We now know that it is more accurate to say that Piketty fudged his homework.
I drew the following five conclusions from The Financial Times’s re-analysis:
Not all differences are errors
They essentially agree
Not all differences are equally important
The F.T.'s bottom line is muddier than it looks
This is a debate about wealth inequality, not income inequality.
Of course, one can’t help but be reminded of the kerfuffle about an earlier research paper written by Carmen Reinhart and Ken Rogoff. I fear the similarities are deeper than most realize, with partisans already engaged in gaining political mileage out of sloganeering about fairly inconsequential spreadsheet errors, rather than digging more deeply into what the data actually say. The difference is that this time the political football is an empirical result that is an article of faith among liberals, rather than conservatives. Beyond that, though, it’s different mudslingers, but similar mud.
The Financial Times analysis is definitely provocative. While it raises important questions, I’m not convinced it does more than that. Mr. Piketty has already written a fairly general response to The F.T.'s analysis, but he has yet to respond to the specific charges made. One hopes that in time Mr. Piketty will write a longer and more detailed point-by-point reply, admitting errors where they exist, and defending his data choices where they are defensible.
And perhaps some good will come from all this. The clearest effect of Mr. Piketty’s efforts is that he has brought new attention to the distribution of wealth. I believe that interest will continue to improve and refine our understanding of the evolution of wealth inequality.
[I]s it possible that Piketty’s whole thesis of rising wealth inequality is wrong? Giles argues that it is:
The exact level of European inequality in the last fifty years is impossible to determine, as it depends on the sources one uses. However, whichever level one picks, the lines in red in the graph show that – unlike what Prof. Piketty claims – wealth concentration among the richest people has been pretty stable for 50 years in both Europe and the US.
There is no obvious upward trend. The conclusions of Capital in the 21st century do not appear to be backed by the book’s own sources.
OK, that can’t be right — and the fact that Giles reaches that conclusion is a strong indicator that he himself is doing something wrong. ...
The point is that Giles is proving too much; if his attempted reworking of Piketty leads to the conclusion that nothing has happened to wealth inequality, what that really shows is that he’s doing something wrong.
None of this absolves Piketty from the need to respond to each of the individual questions. But anyone imagining that the whole notion of rising wealth inequality has been refuted is almost surely going to be disappointed.