Monetary Policy with Model Uncertainty: Distribution Forecast Targeting

We examine optimal and other monetary policies in a linear-quadratic setup with relatively general forms of model uncertainty. The forms of uncertainty our framework encompasses include: simple i.i.d. model deviations; serially correlated model deviations; estimable regime-switching models; more complex structural uncertainty, such as uncertainty about a set of structurally very different models, for instance, backward- and forward-looking models; central-bank judgment about the state of model uncertainty; and so forth. We provide an algorithm for finding the optimal policy as well as solutions for arbitrary reaction functions. This allows us to compute and plot consistent distribution forecasts---fan charts---of target variables and instruments. Our methods hence extend certainty equivalence and "mean forecast targeting" to the more general certainty non-equivalence and "distribution forecast targeting."