Stargazers hate clouds. Even modest levels of humidity and wind make it hard to “see” the wonders of the night sky. Very few places on our planet have consistently clear, dark skies.

Central bankers face a similar, albeit earthly, challenge. Even the simplest economic models require estimation of unobservable factors; something that generates considerable uncertainty. As Vice Chairman Clarida recently explained, the Fed depends on new data not only to assess the current state of the U.S. economy, but also to pin down the factors that drive a wide range of models that guide policymakers’ decisions.

In this post, we highlight how the Federal Open Market Committee’s (FOMC’s) views of two of those “starry” guides—the natural rates of interest (r*) and unemployment (u*)—have evolved in recent years. Like sailors under a cloudy sky, central bankers may need to shift course when the clouds part, revealing that they incorrectly estimated these economic stars. The uncertainty resulting from unavoidable imprecision not only affects policy setting, but also complicates policymakers’ communication, which is one of the keys to making policy effective….