Presentation at the HLEG thematic workshop on "Intra-generational and Inter-generational Sustainability", 22-23 September 2014, Rome, Italy, http://oe.cd/StrategicForum2014

1. "Lessons from the 2013 Public Debt and Growth
Debate: How to Assess Economic Sustainability"
Thomas Herndon, Doctoral Candidate
University of Massachusetts Amherst, Department of Economics and
Political Economy Research Institute
9-23-2014

2. Outline
• 2013 Reinhart-Rogoff/HAP Public Debt and Growth Debate
• Problems Identified in literature
• Problems with Causality: Debt -> Growth?
• Endogeneity
• Panizza and Presbitero
• Problems with estimating debt thresholds
• Endogeneity
• Kourtellos, Stengos, Tan
• Heterogeneity
• Eberhardt and Presbitero

5. Herndon, Ash, Pollin (2014). Cambridge Journal of Economics

6. Herndon, Ash, Pollin (2014). Cambridge Journal of Economics

7. Herndon, Ash, Pollin (2014). Cambridge Journal of Economics

8. Problems with Causality
• Does high debt cause slow growth, or is it reverse causality?
• Early review of Literature – Panizza and Presbitero (2013)
• “While many papers have found a negative correlation between debt and
growth, our reading of the empirical literature is that theres is no paper that
can make a strong case for a causal relationship going from debt to economic
growth.”
• Dube (2013) Comment

9. Dube (2013) Comment on Causality

10. Dube Comment (2013), Evidence for Reverse
Causality

11. Problems with Estimating Debt Threshold
Identified by the Literature
• Endogeneity
• Most papers use a PSTR model based on either Hansen (1999) or Hansen and
Caner (2005), however these rely on an exogenous threshold variable.
• Kourtellos, Stengos and Tan (2012) – “One difficulty with the above studies is
that they ignore the problem of endogeneity in the threshold variable. This
is important because, as Kourtellos, Stengos, and Tan (2011) argue, if the
threshold variable is endogenous, the above approaches will yield
inconsistent parameter estimates for the regime-specific partial effects.”
• Heterogeneity
• Eberhardt and Presbitero (2013) – Heterogeneity makes it difficult to
determine whether threshold is within or across countries.

12. Checherita and Rother (2010) replication with RR data. They fit a quadratic curve in
their regression, and found an inverted U-shape. Below is a loess regression for five
year future growth and debt/GDP, which replicates their finding.

13. But there’s a lot of heterogeneity, with many countries showing a positive relationship
at high levels of debt. The inverted U-shape appears to be driven by the outlier of
Ireland. (Note, RR dataset doesn’t include Luxembourg, while C-R does. )

14. Loess regression, but excluding Ireland.

15. More Recent Lit on Debt and Growth
confirms our finding of lack of threshold.
• Pescatori, Sandri, and Simon (2014) - Debt and Growth: Is There a Magic
Threshold?
• Lof and Malinen (2014) – Does Sovereign Debt Weaken Growth? A Panel
VAR Analysis
• Eberhardt (2013) - Nonlinearities in the Relationship between Debt and
Growth: Evidence from Co-Summability Testing
• Eberhardt and Presbitero (2013) - This Time They’re Different:
Heterogeneity and Nonlinearity in the Relationship between Debt and
Growth
• Egert (2013) – The 90% Public Debt Threshold: The Rise and Fall of a
Stylized Fact
• Bell, Johnston and Jones (2013) - Stylised fact or situated messiness? The
diverse effects of increasing debt on national economic growth

16. Bank of England: 300 Years of Public Debt and Interest Rates

17. Results of Austerity? De Grauwe and Ji (2013)
Austerity and GDP Growth 2011-2012 Austerity and Increases in Debt/GDP 2011-2012
Source: Financial Times and Datastream. Note: The Greek debt ratio excludes the
debt restructuring of end 2011 that amounted to about 30% of GDP.