The "how" question is easily answered in most economics textbooks. Once the Federal Open Market Committee (FOMC) decides to cut the federal funds rate by 50 basis points, the Open Market Trading Desk purchases the quantity of government securities necessary to reach the new federal funds rate. The graph on the right shows how open-market purchases could lower the federal funds rate from 5.25% to 4.75%.
So far, I have stuck to the facts without building a model of the Fed's behavior. Economists sometimes find it convenient to model the behavior of the Fed in terms of a monetary policy reaction function (MPRF). The following is an example of an MPRF from Ben Bernanke and Robert Frank's Principles of Economics:
In addition to equations, economists often use graphs to depict models. The following graph shows the simple MPRF with the real interest rate on the Y-axis and the inflation rate on the X-axis. Assume a 3% actual and long-run target inflation rate.
1. Refer to the simple MPRF equation. A downward shift of the MPRF could be accomplished by a reduction in the long-run target real interest rate (r*). The Fed typically sets r* in line with the equilibrium real interest rate that prevails in the market for loanable funds. Is there reason to believe that the recent financial turbulence has disrupted investment, private saving, public saving, or net capital inflows?
2. A downward shift of the MPRF could also be accomplished by an increase in the long-run target inflation rate. Is there reason to believe that the Fed has increased the long-run target inflation rate?
3. Are there other factors that the Fed should consider in its MPRF?