Tom McDonnell: Reinhart and Rogoff's finding that the growth rate starts to decline once the public debt to GDP ratio exceeds 90% has become embraced as a stylised fact by the commentariat and in particular by the austerians. However, a recent paper by Thomas Herndon, Michael Ash and Robert Pollin has critiqued this finding. As Slate reports here, Herndon et al. find that the Reinhart and Rogoff result is attributable to a coding error, and they also raise other methodological objections. Herndon et al. find that overall the evidence contradicts Reinhart and Rogoff's claim that public debt loads greater than 90% of GDP consistently reduce GDP growth.
It will be interesting to see how Reinhart and Rogoff respond to the Herndon critique.