Ben Bernanke reinforced his standing as the most activist Federal Reserve chairman in history by doing the unexpected: nothing. Bernanke said the Fed must determine its policies based on "what's needed for the economy", even if it surprises markets. The decision to abstain from tapering bond purchases underscored Bernanke's willingness to do anything to lower unemployment, according to Lou Crandall, chief economist at Wrightson ICAP. Bernanke, whose term ends on January 31, has kept interest rates near zero for almost five years and swelled the Fed's balance sheet to a record US$3.66 trillion through buying treasuries and mortgage-backed securities. In his press conference on Wednesday and in his policies since the financial crisis, Bernanke has refused to give up on the power of monetary policy or the ability of the US economy to heal from the worst recession since the Depression. To the extent "our policy decision today makes conditions just a little bit easier, that's desirable," Bernanke said. "We want to make sure that the economy has adequate support." Central bankers in December last year linked the federal funds rate to inflation and unemployment. They said that the rate would remain in a range of zero to 0.25 per cent so long as the jobless rate was above 6.5 per cent and inflation forecasts did not exceed 2.5 per cent. Bernanke suggested at his press conference the unemployment threshold may be too high partly because the rate is not telling the whole story of labour market conditions. Unemployment fell to 7.3 per cent last month as workers left the labour force.