Modeling U.S. monetary policy during the global financial crisis and lessons for Covid-19.

The paper formulates the modeling of unconventional monetary policy and critically evaluates its effectiveness to address the Global Financial Crisis. We begin with certain principles guiding general scientific modeling and focus on Milton Friedman's 1968 Presidential Address that delineates the strengths and limitations of monetary policy to pursue certain goals. The modeling of monetary policy with its novelty of quantitative easing to target unusually high unemployment is evaluated by a Markov switching econometric model using monthly data for the period 2002-2015.