Federal Reserve Bank of Chicago boss Charles Evans looks determined to sway the Federal Reserve Board’s powerful monetary-policy committee toward using specific economic-indicator levels to help define the Fed’s next interest rate move. Yet even the Federal Reserve system’s biggest champion of these so-called “numerical thresholds” sees them as only a temporary tool to be used in unusual times (such as those we have now); he doesn’t favour them as the basis for a permanent framework for defining interest-rate policy at the U.S. central bank.