Just went to a talk by Jesse Shapiro where he gave an overview his work on the media, much of it joint with Matt Gentzkow. One theme is that competing newspapers with different party affiliations generate more information for the electorate. How fitting to return to my office and find this Guardian discussion (by Howard Reed) on FT takedown of Piketty (by Chris Giles). Main issue is that FT did not account for differences in way wealth is measured across separate series which are then merged into one time series:
To summarise, Chris Giles’s investigation of Piketty’s data has uncovered some errors and inconsistencies which Piketty will hopefully address in future work. This shows the importance of quality assurance and third party checking of all results from statistical analysis – particularly when they involve spreadsheets, where it is very easy to make errors.
However, Giles then goes on to make a very serious error of his own in handling the UK data: he treats changes in the way wealth inequality is measured over the decades as if they were real changes in the underlying distribution of wealth. This error leads him to the misleading conclusion that wealth inequality fell in the UK between 1980 and 2010, whereas in fact it has increased (although not by quite as much as Piketty’s published results would suggest).
In some ways, the Guardian discussion is even clearer than Piketty’s own response today. This reflects the universal truth that (good) referees and discussants can often explain your paper better than you can yourself.
But this all leaves one question unanswered: When is Piketty going to respond to Debraj? He disputed Piketty’s theory not his data.