Glenn Rudebusch is making sense. John Taylor is not.
Calculated Risk sends us to Jan Hatzius:
Calculated Risk: The Taylor Rule Debate: [S]everal highly respected voices have weighed in on this debate, with arguments that imply a smaller need for Fed balance sheet expansion than suggested by our calculations. The first challenge came from Professor John Taylor—father of the eponymous rule—at an Atlanta Fed conference (see “Systemic Risk and the Role of Government,” May 12, 2009). Taylor argued that his rule implies a fed funds rate of +0.5%. He specifically attacked a reported Fed staff estimate of an “optimal” Taylor rate of -5% as having "... both the sign and the decimal point wrong.”
What’s going on? The answer can be seen in a note published by Glenn Rudebusch of the San Francisco Fed [in May]; it justifies the Fed’s -5% figure and reads like a direct reaction to Taylor’s criticism, even though it does not reference his speech (see “The Fed’s Monetary Policy Response to the Current Crisis,” FRBSF Economic Letter 2009-17, May 22, 2009). The difference is fully explained by two choices. First, Taylor uses his “original” rule with an assumed (but not econometrically estimated) coefficient of 0.5 on both the output gap and the inflation gap, while the Fed uses an estimated rule with a bigger coefficient on the output gap. Second, Taylor uses current values for both gaps, while the Fed’s estimate of a -5% rate refers to a projection for the end of 2009, assuming a further rise in the output gap and a decline in core inflation.
And Glenn Rudebusch:
FRBSF Economic Letter: The Fed's Monetary Policy Response to the Current Crisis (2009-17, 5/22/2009): A rough guideline for setting the federal funds rate that captures the Fed's behavior over the past two decades is provided by a simple equation that relates the funds rate to the inflation and unemployment rates... a statistical regression of the funds rate on the inflation rate and on the gap between the unemployment rate and the Congressional Budget Office's estimate of the natural, or normal, rate of unemployment. The resulting empirical policy rule of thumb—a so-called Taylor rule—recommends lowering the funds rate by 1.3 percentage points if core inflation falls by one percentage point and by almost two percentage points if the unemployment rate rises by one percentage point. As shown in Figure 2, this simple rule of thumb captures the broad contours of policy over the past two decades.... The estimated Taylor rule can also be used in conjunction with economic forecasts to provide a rough benchmark for calibrating the appropriate stance of monetary policy going forward.... The recommended future policy setting of the funds rate based on the estimated historical policy rule and these economic forecasts is given as the dashed line in Figure 2.... [I]n order to deliver a degree of future monetary stimulus that is consistent with its past behavior, the FOMC would have to reduce the funds rate to -5% by the end of this year—well below its lower bound of zero.... The shaded area in Figure 2 is the difference between the current zero-constrained level of the funds rate and the level recommended by the policy rule. It represents a monetary policy funds rate shortfall, that is, the desired amount of monetary policy stimulus from a lower funds rate that is unavailable because nominal interest rates can't go below zero. This policy shortfall is sizable.... 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.
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, and Williams 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." Other central banks have been even more explicit about the duration of low rates. For example, the central bank of Sweden has recently stated explicitly that it expects to keep its policy rate at a low level until the beginning of 2011. Rudebusch and Williams (2008) describe how such revelation of central bank interest rate projections may help a central bank achieve its policy goals...