James K. Galbraith — Piketty's World Inequality Review: A Critical Analysis

My new essay examines the question from three points of view: the coverage provided by tax data in the world economy, the consistency of tax data with other sources of information on income inequality, and the peculiarities of tax-based measurement of inequality in the United States. It goes on to make a comparison with measures drawn from other forms of administrative data—specifically payroll records, used by the University of Texas Inequality Project—which are generally more consistent with records of inequality measured in household surveys than are the WIR’s tax records.

In brief summary, the review shows that by comparison with payroll and survey data, available records from tax files are relatively sparse, and biased toward wealthier countries and those that were once British colonies, which imposed income tax. It shows that tax data are far less consistent with survey and payroll records than are the latter two with each other. And it shows that even within the United States, a country with good tax records by world standards, changes in tax law distort the WIR’s measures of changes in the top income shares, while a misunderstanding of the nature of low-income tax filers in the US leads to a dramatic but nonsensical claim that the earnings of the bottom 50 percent of Americans have “collapsed” in recent decades. 

Overall, the review casts doubt on claims by the authors of the World Inequality Report to have produced major advances in the study of world economic inequality, and documents that many of the findings touted in the Report as new and unprecedented have in fact been reported in the literature for years, even decades in some cases....

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Piketty's World Inequality Review: A Critical Analysis

James K. Galbraith | Lloyd M. Bentsen Jr. Chair in Government/Business Relations and Professor of Government at the Lyndon B. Johnson School of Public Affairs, The University of Texas at Austin