One can only say that if the bank policy succeeds in stabilizing prices, the bank rate must have been brought in line with the natural rate, but if it does not, it must not have been.”8 What is more, ultra-expansionary monetary policy compressed long-term interest rates for a prolonged period of time, which may feed into estimates of the natural rate.
In addition, many methods fail to take account of the risk dimension that prevails in the real economy. They often use as a starting point yields on government bonds which are regularly deemed riskless. But the concept of the natural rate refers to characteristics of the real economy, so it would be appropriate to apply a risk-bearing return on capital.