I review a book by three sociologists.

Most of the conventional wisdom about relative economic well-being, including the famous studies by Thomas Piketty and Emmanuel Saez, commits the time-series cross-section fallacy. Rank, Hirschl, and Foster did not set out to debunk this fallacy or to attack the many economists guilty of it. Instead, they took what seemed to them a natural approach for studying the evolution of wealth and poverty: longitudinal data. The result, in my reading, is that, like the boy in the fable, they have in an innocent, unintended fashion exposed statistical nakedness among many economists who are regarded as experts on the topic of inequality.