The researchers Cynthia Wu and Fan Dora Xia estimate that the US Federal Reserve’s open-ended asset purchases (so-called quantitative easing, or QE) have led to an effective US policy rate of -1.6%. QE helped American exports by weakening the dollar relative to other currencies.
而货币政策方面最具野心的国家是美国。据研究者芝加哥大学教授吴静和夏凡估计，美联储的无限期资产购买计划（所谓的量化宽松政策或QE）导致美国实际政策利率为-1.6%。量化宽松政策通过削弱美元兑其他货币的汇率协助美国出口。一旦日本启动自己的量化宽松政策之后领导日元迅速贬值，而那使得欧元走强。