Economic theory suggests that it is useful for the Fed to communicate the likely duration of any policy shortfall. Monetary policy is in large part a process of shaping private-sector expectations about the future path of short-term interest rates,which affect long-term interest rates and other asset prices, in order to achieve various macroeconomic objectives (McGough,Rudebusch,andWilliams 2005).In the current situation,the FOMC (2009) has noted that it“anticipates that economic conditions are likely to warrant exceptionally low levels of the federal funds rate for an extended period.”