In the debate over government spending, the central data point wielded by fans of austerity is the claim that once a country reaches a debt load over 90 percent of its economy — a threshold the United States is approaching — economic growth goes into a tailspin. That argument came from a 2010 study by Carmen Reinhart and Kenneth Rogoff. After surveying a wide number of countries, they found that, on average, once the 90 percent mark is crossed, economic growth slows. Though the paper always had problems that kept many economists from embracing it, that didn’t stop it from becoming “the most influential article cited in public and policy debates about the importance of debt stabilization” as Slate’s Matt Yglesias put it.
There were already problems with the Reinhart-Rogoff study, but up until now, other researchers haven’t been able to replicate or pick through its numbers. A new paper finally has, and as Mike Konczal over at Next New Deal reports, it dug up some truly mortal flaws.
First, Reinhart and Rogoff excluded the post-war years for certain countries that enjoyed robust economic growth despite debt levels well over 90 percent. They also chose a skewed method of weighting the data: for example, New Zealand’s single year of terrible growth while over the 90 percent threshold wound up counting just as much as Britain’s 19 years of healthy growth. And they even incorrectly input at least one Excel spreadsheet formula, wrongly excluding several countries form their calculations.
In short, the central argument in support of austerity — cited by MSNBC’s Joe Scarborough, the New York Times’ David Brooks, and multiple times by House Budget Committee Chairman Rep. Paul Ryan (R-WI) — is now defunct. No one disputes that a country should avoid a big build-up in debt over the long-term. But every concrete signal we’re getting from the American economy — our high unemployment, our low inflation, our extraordinarily low interest rates, and our negative real interest rates — are a signal that more debt spending in the short term to fight the depression is perfectly appropriate. Thanks to the austerity drive that was heavily influenced by Reinhart and Rogoff’s study, American lawmakers ignored those signals (and plenty of others) and cut spending, delivering the most destructive fiscal policy we’ve had in any recession since at least 1980.
Economist Jared Bernstein just went through the errors the new Herndon, Ash, and Polin paper found in the Reinhart and Rogoff study, and reworked the latter’s results to account for the deficiencies. As a result, the dramatic slow down in economic growth above the 90 percent debt-to-GDP ratio almost entirely disappears:
And even though 2.2 percent growth isn’t stellar, the apples-to-apples comparison problem and the correlation-causation problem both still remain, as Bernstein points out.
Reinhart and Rogoff have responded to criticisms. Their rejoinder can be read here.