Optimal Monetary Policy under Commitment with a Zero Bound on Nominal Interest Rates
在一个前瞻性新凯恩斯模型中研究名义利率受零下限约束时的最优承诺政策，发现政策应更激进地降息，且理性预期会放大负面冲击的影响，但最优政策下零利率并不常见，也不导致正的平均通胀。
We determine optimal monetary policy under commitment in a forward-looking New Keynesian model when nominal interest rates are bounded below by zero. The lower bound represents an occasionally binding constraint that causes the model and optimal policy to be nonlinear. A calibration to the U.S. economy suggests that policy should reduce nominal interest rates more aggressively than suggested by a model without lower bound. Rational agents anticipate the possibility of reaching the lower bound in the future and this amplifies the effects of adverse shocks well before the bound is reached. While the empirical magnitude of U.S. mark-up shocks seems too small to entail zero nominal interest rates, shocks affecting the natural real interest rate plausibly lead to a binding lower bound. Under optimal policy, however, this occurs quite infrequently and does not imply positive average inflation rates in equilibrium. Interestingly, the presence of binding real rate shocks alters the policy response to (non-binding) markup shocks.