Home > Uncategorized > How Much Unemployment Was Caused by Reinhart and Rogoff’s Arithmetic Mistake?

How Much Unemployment Was Caused by Reinhart and Rogoff’s Arithmetic Mistake?

From: Dean Baker

That’s the question millions will be asking when they see the new paper by my friends at the University of Massachusetts, Thomas Herndon, Michael Ash, and Robert Pollin. Herndon, Ash, and Pollin (HAP) corrected the spreadsheets of Carmen Reinhart and Ken Rogoff. They show the correct numbers tell a very different story about the relationship between debt and GDP growth than the one that Reinhart and Rogoff have been hawking.

Just to remind folks, Reinhart and Rogoff (R&R) are the authors of the widely acclaimed book on the history of financial crises, This Time is Different. They have also done several papers derived from this research, the main conclusion of which is that high ratios of debt to GDP lead to a long periods of slow growth. Their story line is that 90 percent is a cutoff line, with countries with debt-to-GDP ratios above this level seeing markedly slower growth than countries that have debt-to-GDP ratios below this level. The moral is to make sure the debt-to-GDP ratio does not get above 90 percent.

There are all sorts of good reasons for questioning this logic. First, there is good reason for believing causation goes the other way. Countries are likely to have high debt-to-GDP ratios because they are having serious economic problems.

Second, as Josh Bivens and John Irons have pointed out, the story of the bad growth in high debt years in the United States is driven by the demobilization after World War II. In other words, these were not bad economic times, the years of high debt in the United States had slow growth because millions of women opted to leave the paid labor force.

Third, the whole notion of public debt turns out to be ill-defined. Countries can sell off assets to pay down debts, would this avoid the R&R high debt twilight zone of slow growth? In fact, even the value of debt itself is not constant.Long-term debt issued in times of low interest rates will fall in value when interest rates rise. If there is a high debt twilight zone effect as R&R claim, then we can just buy back bonds at steep discounts and send our debt-to-GDP ratio plummeting.

But HAP tells us that we need not concern ourselves with any arguments this complicated. The basic R&R story was simply the result of them getting their own numbers wrong.

After being unable to reproduce R&R’s results with publicly available data, HAP were able to get the spreadsheets that R&R had used for their calculations. It turns out that the initial results were driven by simple computational and transcription errors. The most important of these errors was excluding four years of growth data from New Zealand in which it was above the 90 percent debt-to-GDP threshold. When these four years are added in, the average growth rate in New Zealand for its high debt years was 2.6 percent, compared to the -7.6 percent that R&R had entered in their calculation.

Since R&R country weight their data (each country’s growth rate has the same weight), and there are only seven countries that cross into the high debt region, correcting this one mistake alone adds 1.5 percentage points to the average growth rate for the high debt countries. This eliminates most of the falloff in growth that R&R find from high debt levels. (HAP find several other important errors in the R&R paper, however the missing New Zealand years are the biggest part of the story.)

This is a big deal because politicians around the world have used this finding from R&R to justify austerity measures that have slowed growth and raised unemployment. In the United States many politicians have pointed to R&R’s work as justification for deficit reduction even though the economy is far below full employment by any reasonable measure. In Europe, R&R’s work and its derivatives have been used to justify austerity policies that have pushed the unemployment rate over 10 percent for the euro zone as a whole and above 20 percent in Greece and Spain. In other words, this is a mistake that has had enormous consequences.

In fairness, there has been other research that makes similar claims, including more recent work by Reinhardt and Rogoff. But it was the initial R&R papers that created the framework for most of the subsequent policy debate. And HAP has shown that the key finding that debt slows growth was driven overwhelmingly by the exclusion of 4 years of data from New Zealand.

If facts mattered in economic policy debates, this should be the cause for a major reassessment of the deficit reduction policies being pursued in the United States and elsewhere. It should also cause reporters to be a bit slower to accept such sweeping claims at face value.

(Those interested in playing with the data itself can find it at the website for the Political Economic Research Institute.)

From original website

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  1. April 16, 2013 at 6:23 pm | #1

    See “EXCESS DEBTS, Very Visible” here:
    http://www.showrealhist.com/debtGDP_whys.html

  2. BFWR
    April 16, 2013 at 6:49 pm | #2

    Not surprising. Policies of all stripes are often engaged in for very long periods of time…and their economic and more importantly their human consequences…are virtually ignored.

    None of what I just said, or what was posted in the article though should be understood as saying that a policy of continuous build up of debt…is good .

    What we need is a policy of balancing the ability to pay debt with….enough total individual demand/income….as is necessary to accomplish this. And in order for that to occur ……….is a SOCIAL CREDIT to balance the lack of balance caused by BOTH the accounting flaw that, in a profit making economic system, enforces a scarcity of total individual incomes in comparison to total prices, AND the replacement of the rational need for employment in a technologically advanced economy.

    Ah, but technology creates jobs! Well, not really. Nominally jobs are being destroyed faster than they are being created…..and much more important than that…..why maintain the current centralizing and onerous system….just so everyone can have an increasingly unneeded and meaningless job!!!!!!!!!!!!!!!!!!!!!!!

    Wisdom integrates all realities and makes for the optimal ethical and economic policy….if we will only contemplate it and trust it.

  3. April 16, 2013 at 6:53 pm | #3

    The attention given to Reinhart and Rogoff (RR) shows how low is the standard of empirical research in economics. The data across different time and geographies, were analysed for correlations between two economic variables, as though the data are sampling from same probability distribution, committing the ergodic fallacy.

    The correlations are statistically insignificant (see Figure 4 of Herndon et al.) because there are other variables which have significant impact on the correlations. These other significant variables are different across time and geographies. For example, many countries were selling government assets through massive privatizations in recent decades. Public debt has a different significance, depending on the amount of public assets (which earn dividends to pay interest in the debt), just to name one factor.

    Empirical research in economics rarely get criticized to the extent they deserve, due to repressive journal policies. Herndon et al. shows another example of incompetent or deceptive manipulation of data by RR. Will they get published in a journal? The standard of econometrics on applied economics is low and its impact on theory negligible, resulting in a parallel universe of dogmatic and false theories, unchecked by wishy-washy data analysis.

  4. April 16, 2013 at 7:14 pm | #4

    Shared excerpt: Warren Mosler posted in MMT Deficit Owl USA Committee
    Researchers Finally Replicated…
    Warren Mosler 1:08pm Apr 16
    Researchers Finally Replicated Reinhart-Rogoff, and There Are Serious Problems.

    Apr 16, 2013Mike Konczal
    In 2010, economists Carmen Reinhart and Kenneth Rogoff released a paper, “Growth in a Time of Debt.” Their “main result is that…median growth rates for countries with public debt over 90 percent of GDP are roughly one percent lower than otherwise; average (mean) growth rates are several percent lower.” Countries with debt-to-GDP ratios above 90 percent have a slightly negative average growth rate, in fact.

    This has been one of the most cited stats in the public debate during the Great Recession. Paul Ryan’s Path to Prosperity budget states their study “found conclusive empirical evidence that [debt] exceeding 90 percent of the economy has a significant negative effect on economic growth.” The Washington Post editorial board takes it as an economic consensus view, stating that “debt-to-GDP could keep rising — and stick dangerously near the 90 percent mark that economists regard as a threat to sustainable economic growth.”

    Is it conclusive? One response has been to argue that the causation is backwards, or that slower growth leads to higher debt-to-GDP ratios. Josh Bivens and John Irons made this case at the Economic Policy Institute. But this assumes that the data is correct. From the beginning there have been complaints that Reinhart and Rogoff weren’t releasing the data for their results (e.g. Dean Baker). I knew of several people trying to replicate the results who were bumping into walls left and right – it couldn’t be done.

    In a new paper, “Does High Public Debt Consistently Stifle Economic Growth? A Critique of Reinhart and Rogoff,” Thomas Herndon, Michael Ash, and Robert Pollin of the University of Massachusetts, Amherst successfully replicate the results. After trying to replicate the Reinhart-Rogoff results and failing, they reached out to Reinhart and Rogoff and they were willing to share their data spreadhseet. This allowed Herndon et al. to see how how Reinhart and Rogoff’s data was constructed.

    They find that three main issues stand out. First, Reinhart and Rogoff selectively exclude years of high debt and average growth. Second, they use a debatable method to weight the countries. Third, there also appears to be a coding error that excludes high-debt and average-growth countries. All three bias in favor of their result, and without them you don’t get their controversial result. Let’s investigate further:

    Selective Exclusions. Reinhart-Rogoff use 1946-2009 as their period, with the main difference among countries being their starting year. In their data set, there are 110 years of data available for countries that have a debt/GDP over 90 percent, but they only use 96 of those years. The paper didn’t disclose which years they excluded or why.

    Herndon-Ash-Pollin find that they exclude Australia (1946-1950), New Zealand (1946-1949), and Canada (1946-1950). This has consequences, as these countries have high-debt and solid growth. Canada had debt-to-GDP over 90 percent during this period and 3 percent growth. New Zealand had a debt/GDP over 90 percent from 1946-1951. If you use the average growth rate across all those years it is 2.58 percent. If you only use the last year, as Reinhart-Rogoff does, it has a growth rate of -7.6 percent. That’s a big difference, especially considering how they weigh the countries.

    Unconventional Weighting. Reinhart-Rogoff divides country years into debt-to-GDP buckets. They then take the average real growth for each country within the buckets. So the growth rate of the 19 years that England is above 90 percent debt-to-GDP are averaged into one number. These country numbers are then averaged, equally by country, to calculate the average real GDP growth weight.

    In case that didn’t make sense let’s look at an example. England has 19 years (1946-1964) above 90 percent debt-to-GDP with an average 2.4 percent growth rate. New Zealand has one year in their sample above 90 percent debt-to-GDP with a growth rate of -7.6. These two numbers, 2.4 and -7.6 percent, are given equal weight in the final calculation, as they average the countries equally. Even though there are 19 times as many data points for England.

    Now maybe you don’t want to give equal weighting to years (technical aside: Herndon-Ash-Pollin bring up serial correlation as a possibility). Perhaps you want to take episodes. But this weighting significantly reduces the average; if you weight by the number of years you find a higher growth rate above 90 percent. Reinhart-Rogoff don’t discuss this methodology, either the fact that they are weighing this way or the justification for it, in their paper.

    Coding Error. As Herndon-Ash-Pollin puts it: “A coding error in the RR working spreadsheet entirely excludes five countries, Australia, Austria, Belgium, Canada, and Denmark, from the analysis. [Reinhart-Rogoff] averaged cells in lines 30 to 44 instead of lines 30 to 49…This spreadsheet error…is responsible for a -0.3 percentage-point error in RR’s published average real GDP growth in the highest public debt/GDP category.” Belgium, in particular, has 26 years with debt-to-GDP above 90 percent, with an average growth rate of 2.6 percent (though this is only counted as one total point due to the weighting above).

    Being a bit of a doubting Thomas on this coding error, I wouldn’t believe unless I touched the digital Excel wound myself. One of the authors was able to show me that, and here it is. You can see the Excel blue-box for formulas missing some data:

    This error is needed to get the results they published, and it would go a long way to explaining why it has been impossible for others to replicate these results. If this error turns out to be an actual mistake Reinhart-Rogoff made, well, all I can hope is that future historians note that one of the core empirical points providing the intellectual foundation for the global move to austerity in the early 2010s was based on someone accidentally not updating a row formula in Excel.

    So what do Herndon-Ash-Pollin conclude? They find “the average real GDP growth rate for countries carrying a public debt-to-GDP ratio of over 90 percent is actually 2.2 percent, not -0.1 percent as [Reinhart-Rogoff claim].” Going further into the data, they are unable to find a breakpoint where growth falls quickly and significantly.

    This is also good evidence for why you should release your data online, so it can be probably vetted. But beyond that, looking through the data and how much it can collapse because of this or that assumption, it becomes quite clear that there’s no magic number out there. The debt needs to be thought of as a response to the contigent circumstances we find ourselves in, with mass unemployment, a Federal Reserve desperately trying to gain traction at the zero lower bound, and a gap between what we could be producing and what we are. The past guides us, but so far it has failed to provide an emergency cliff. In fact, it tells us that a larger deficit right now would help us greatly.

    View Post on Facebook
    ****Conclusion: So what do Herndon-Ash-Pollin conclude? They find “the average real GDP growth rate for countries carrying a public debt-to-GDP ratio of over 90 percent is actually 2.2 percent, not -0.1 percent as [Reinhart-Rogoff claim].”

  5. merijnknibbe
    April 16, 2013 at 7:47 pm | #5

    We should not throw out the R@R baby (financial capitalism is unstable and financial crises have long lasting consequences) with their weird growth story bathwater: http://rwer.wordpress.com/2011/01/23/doubts-about-debts-reinhart-reinhart-and-rogoff-on-the-nature-of-modern-capitalism-1800-2010/

  6. April 23, 2014 at 10:32 am | #6

    As Göran Therborn wrote in his book The killing fields of inequality, surplus death caused by high unemployment should be counted in tens of thousands, and people have been sentenced for crime against humanity for less than that in the International Court at Haag.

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