The 90% public debt threshold: the rise and fall of a stylized fact

We put the original Reinhart-Rogoff data-set, made public by Herndon et al. (2013), to a formal econometric test to identify public debt thresholds endogenously. We show that the nonlinear relation between debt and growth is not robust. Taken with a pinch of salt, our results suggest, however, that a negative association between central government debt and growth may set in at debt levels as low as 20% of GDP. Further (and greater) thresholds may exist, but their magnitude is uncertain. For general government debt, the threshold is considerably higher at about 50%. Country-specific estimates reveal a large amount of cross-country heterogeneity. For some countries including the United States, a nonlinear negative link can be detected at about 30% of GDP. For others, no nonlinearities can be established. Our results are a formal econometric confirmation that the 90% public debt threshold is not in the Reinhart-Rogoff data. But our results also seem to suggest that public debt be associated with poor economic performance at fairly moderate public debt levels. The absence of threshold effects or low estimated thresholds may not preclude the emergence of further threshold effects, especially as public debt levels are rising to unprecedentedly high levels.