The empirical evidence that he uses to support this thesis with respect to income inequality in the United States is the same used by Emmanuel Saez, who has often collaborated with Piketty in his research.21 The Piketty income data do not include transfer payments, which make up a majority of the income of the bottom 40 percent of the population. His data also overstate the income of higher-income individuals by imputing to them income such as unrealized capital gains, which they do not actually receive.
