Unfortunately, many of these methods cannot be applied to the most important questions facing economic policymakers. So the evidence does not really tell us whether a heavily indebted country should pay down its debt or borrow and invest more.
许多计量经济学家的职业生涯就是在寻找明智的构建因果方向之法。不幸的是，这些方法大多不能用于经济决策者所面临的最重要的问题。因此证据并不能真的告诉我们高度负债的国家应该多还钱还是借更多钱用于投资。