A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk Nonlinearities in the relationship between debt and growth: (no) evidence from over two centuries 2 Abstract: I revisit the popular concern over a nonlinearity or threshold in the relationship between public debt and growth employing long time series data from up to 27 countries. My empirical approach recognises that standard time series arguments for long-run equilibrium relations between integrated variables (cointegration) break down in nonlinear specifications such as those predominantly applied in the existing debt-growth literature. Adopting the novel co-summability approach my analysis overcomes these difficulties to find no evidence for a systematic long-run relationship between debt and growth in the bivariate and economic theory-based multivariate specifications popular in this literature.Keywords: public debt; economic growth; nonlinearity; summability and co-summability JEL classification: H63, C22, E62, O40 3 1 Introduction "The latest research [by Reinhart and Rogoff] suggests that once debt reaches more than about 90% of GDP the risks of a large negative impact on long term growth become highly significant."George Osborne, Mais Lecture, February 24, 2010 "The study [Reinhart and Rogoff (2010b)] found conclusive empirical evidence that total debt exceeding 90 percent of the economy has a significant negative effect on economic growth."'The Path to Prosperity,' House Committee on the Budget, April 5, 2011 Despite the rhetoric adopted by a number of governments and opposition parties over recent years, determining a causal link from public debt to long-run growth as well as the potential nonlinearity of this relationship are widely regarded as unresolved empirical issues (IMF, 2012;Panizza and Presbitero, 2014). As above quotes indicate the most influential research on the debt-growth nexus in recent years is unarguably the work by Reinhart and Rogoff (2010b) which has been adopted as justification for fiscal austerity measures by politicians on both sides of the Atlantic. Although recent revelations challenged the descriptive analysis carried out in their paper, Reinhart and Rogoff 4 maintain that "the weight of the evidence to date -including this latest comment [by Herndon, Ash and Pollin, 2014] -seems entirely consistent with our original interpretation of the data" (Wall Street Journal 'Real Time Economics' blog, April 16, 2013), namely that "high debt/GDP levels (90 percent and above) are associated with notably lower growth outcomes" (Reinhart and Rogoff, 2010b: 577; see also Rogoff, 2013). Perhaps aware of the tension between the causal interpretation typically read into this type of statement and ...