But a change in a country's interest rates affects the allocation of all its resources: if interest rates are too low, money will flow out of the banks and into the market place where it will trigger price inflation; if rates are too high they raise the cost of borrowing for firms and depress the economy.
而一國利率的變化更會牽動所有的資源配置：利率太低，錢在銀行留不住，會流到市場上來引發通貨膨脹；利率太高，又會使企業貸款的成本提高，造成經濟不景氣，因此升跌幅度總是令各國央行傷透腦筋。