An even more spectacular example of a statistical error and sleight of hand is the widely cited claim of Harvard economists Carmen Reinhart and Kenneth Rogoff that countries’ growth slows sharply if their debt/GDP ratio exceeds 90%. This finding reflected the massive overweighting of one country in their sample, and there was the same confusion between correlation and causation seen in Alesina’s work: high debt levels may cause a lack of growth, or a lack of growth may cause high debt levels.