It may be ironic that the perceived success of central banks and increased credibility of monetary policy, giving rise to enhanced expectations with regard to stability in both inflation and interest rates, could have led to the mispricing of risk and hence enhanced risk taking.
Under QQE, it is necessary to extend these approaches from short-term interest rates to the entire yield curve to establish new criteria for judgment. The Bank of Japan has started to work on both theoretical and empirical approaches to do so in the form of developing the concept of, and measuring, the "natural yield curve."