This policy shortfall is sizable.Indeed,the Fed has been able to ease the funds rate only about half as much as the policy rule recommends.It is also persistent.According to the historical policy rule and FOMC economic forecasts,the funds rate should be near its zero lower bound not just for the next six or nine months,but for several years.The policy shortfall persists even though the economy is expected to start to grow later this year.Given the severe depth of the current recession,it will require several years of strong economic growth before most of the slack in the economy is eliminated and the recommended funds rate turns positive.