Remember that study which found zoning over-regulation costs the economy over $1 trillion? Turns out that number was way off.

In 2015, Professors Chang-Tai Hsieh and Enrico Moretti published a landmark paper on the economic costs of zoning over-regulation. The study got a lot of attention because it calculated housing restrictions cost the economy some $1.6 trillion.

However, the paper made some major blunders in the calculations. The actual number is in fact far higher: $3.39 trillion!!:

Critics may rush to accuse HM of motivated reasoning, but the shoe does not fit.  Their reported figures for the effect of housing deregulation on total GDP and the wage bill turn out to be gross understatements.  The reasonable interpretation, rather, is that authors and referees alike focused so intently on the advanced mathematics that they glossed over some elementary yet crucial errors.  And this is roughly what Hsieh told me: The referees requested some changes to the text (not the tables, which look fine), but these were inconsistently implemented.