"Piketty findings undercut by errors"

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).