This paper studies a New Keynesian business cycle model with agents who are averse to ambiguity (Knightian uncertainty). Shocks to confidence about future TFP are modeled as changes in ambiguity. To assess the size of those shocks, our estimation uses not only data on standard macro variables,...

We estimate a state-of-the-art DSGE model to study the natural rate of interest in the United States over the last 20 years. The natural rate is highly procyclical, and fell substantially below zero in each of the last three recessions. Although the drop was of comparable magnitude across the...

We use rich historical data on military procurement to estimate the effects of government spending. We exploit regional variation in military build-ups to estimate an "open economy relative multiplier" of approximately 1.5. We develop a framework for interpreting this estimate and relating it to...

When the zero lower bound on nominal interest rates binds, monetary policy cannot provide appropriate stimulus. We show that, in the standard New Keynesian model, tax policy can deliver such stimulus at no cost and in a time-consistent manner. There is no need to use inefficient policies such as...

Purely forward-looking versions of the New Keynesian Phillips curve (NKPC) generate too little inflation persistence. Some authors add ad hoc backwardlooking terms to address this shortcoming. We hypothesize that inflation persistence results mainly from variation in the long-run trend component...

Troy Davig and Eric Leeper (2007) have proposed a condition they call the generalized Taylor principle to rule out indeterminate equilibria in a version of the new-Keynesian model where the parameters of the policy rule follow a Markov-switching process. We show that although their condition...

Farmer, Waggoner, and Zha (2009) (FWZ) show that a new Keynesian model with regime-switching monetary policy can support multiple solutions, appearing to contradict findings in Davig and Leeper (2007) (DL). The explanation is straightforward: FWZ derive solutions using a model that differs from...