From the Federal Reserve Bank of New York's Liberty Street Economics blog:
One way to assess the stance of monetary policy is to assert that there is a natural interest rate (NIR), defined as the rate consistent with output being at its potential. Broadly speaking, monetary policy can be seen as expansionary if the policy rate is below the NIR with the gap between the rates measuring the extent of the policy stimulus. Of course, there are many challenges in defining and measuring the NIR, with various factors driving its value over time. A key factor that needs to be considered is the effect of uncertainty and risk aversion on households’ savings decisions. Households’ tolerance for risk tends to be lower during downturns, putting upward pressure on precautionary savings, and thereby downward pressure on the natural interest rate. In addition, uncertainty dictates how much precautionary savings responds to changes in risk aversion. So policymakers need to be aware that rate moves to offset adverse economic conditions that are appropriate in tranquil times may not be sufficient in times of high uncertainty.
As nicely explained in an FRBSF Economic Letter, the NIR is unobservable, but can be tracked with a model that identifies the interest rate that would prevail when output is at its potential—or, absent cost shocks, at a level consistent with stable inflation. In a recent article, we describe the determinants of the natural rate of interest in a fairly standard economic model of the so-called New Keynesian (NK) variety. Our simple setup clearly doesn’t account for all factors driving the natural rate. For example, the closed-economy nature of the model excludes the possibility that global factors such as reserve purchases by foreign central banks or a significant increase in the global supply of savings could be pushing down the equilibrium interest rate. But our model does account for uncertainty and precautionary savings motives. The importance of both of these factors has been apparent during the recent recession, and both are typically ignored in the textbook NK model. Considering the ability of changes in risk aversion and uncertainty to affect the transmission mechanism of shocks and monetary policy allows our setup to clarify how these considerations affect the natural interest rate.
In the standard NK model, the long-run natural interest rate is pinned down by the potential growth rate of the economy and the rate at which agents discount the future. In the medium run, expectations of lower growth can push down the NIR temporarily. Tighter fiscal policy or changes in people’s discount preferences are additional reasons for the NIR to drop....MORE
