The European Central Bank said it has changed interest rates less frequently than the US Federal Reserve because of economic conditions in the euro zone, and not because it is any less committed to meeting its policy goals.
"The ECB's monetary policy strategy... has continuously helped the ECB to carefully calibrate its policy actions to the structural characteristics of the euro area, and most importantly, to anchor inflation expectations," it said in its November monthly bulletin.
The euro zone economy is relatively rigid and has also been hit by an unfavourable mix of shocks in recent years, it said.
"A central bank operating in a relatively rigid economy is able to deliver the same quantum of support to macroeconomic conditions by adjusting its policy instrument in more moderate steps than in a more flexible economy," it said.
The policy stimulus put in place by the ECB in the early years of this decade was therefore "sizeable", it said. The ECB cut its main rate to 2 per cent from 4.75 per cent between 2001 and 2003.
The ECB rejected criticism that it has not been sufficiently active in adjusting rates, and said comparing the frequency and amplitude of central banks' rate moves is an 'overly simplistic way of comparing activism'.
The ECB has changed rates 22 times since it took charge of monetary policy in 1999, and the Fed has adjusted rates more frequently and to a greater extent over this period, but an assessment of whether a central bank is sufficiently active should be based on the vigour and timeliness of decisions taken to meet its policy goals, the ECB said.
A central bank also needs to take account of economic conditions, and the price adjustment process in the euro zone has tended to be rather slow, it said.
The euro zone has also been adversely affected by a decline in productivity growth, which reinforced the economic shock coming from the bursting of the equity market bubble in 2000, whereas the US economy was partly cushioned by stronger productivity growth, it said.
The ECB said its anchoring of inflation expectations at levels close to its price stability definition may also reduce the need for frequent interest rate moves.