Responding to Thomas Piketty’s response (linked here) to the charges raised by the Financial Times, Chris Giles notes that there remain concerns with Piketty’s presentation:

There are a few things on which we agree. First, the source data on wealth inequality is poor. I have written that it is “sketchy” and Prof Piketty says it is “much less systematic than we have for income inequality”. Second, it would have been preferable for Prof Piketty to have used a more sophisticated averaging technique than a simple average of Britain, France and Sweden to derive an estimate for European wealth inequality. Third, the available data suggests a broad trend of reduction in wealth inequality during most of the 20th Century.

There are more aspects on which there remains disagreement. Prof Piketty does not explain the multiple missing data points in his data or tweaks to it; he explains transcription errors as deliberate adjustments to overcome discontinuities in data, but does not provide formulas or an explanation of why these undocumented adjustments should apply to only one data point in a time series; he does not explain why it is consistent to favour household surveys over estate tax records for the US but not the UK; nor why his UK series showing rising wealth inequality differs so materially from his source materials, which show falling UK wealth inequality in eight of the most recent nine decades.