The Deflationary Bias of the ZLB and the FED's Strategic Response
在一个简单分析框架中证明，当自然利率较低且名义利率受零下限约束时，央行的相机抉择会产生通缩偏向，导致平均通胀低于目标；对称双重使命的央行尤其严重，但严格通胀目标制也无法避免。
Abstract The paper shows, in a simple analytical framework, the existence of a deflationary bias in an economy with a low natural rate of interest, a zero lower bound (ZLB) constraint on nominal interest rates and a discretionary Central Bank (CB) with an inflation mandate. The presence of the ZLB prevents the CB from offsetting negative shocks to inflation whereas it can offset positive shocks. This asymmetry pushes average inflation below the target which in turn drags down inflation expectations and reinforces the likelihood of hitting the ZLB. We show that this deflationary bias is particularly relevant for a CB with a symmetric dual mandate (i.e., minimizing deviations from inflation and employment), especially when facing demand shocks. But a strict inflation targeter cannot escape the suboptimal deflationary equilibrium either. The deflationary bias can be mitigated by targeting “shortfalls” instead of “deviations” from maximum employment and/or using flexible average inflation targeting. However, changing monetary policy strategy risks inflation expectations becoming entrenched above the target if the natural interest rate increases.