An illustration One can illustrate the complications that may arise in the actual work with the aid of the type of figure I showed earlier, where one marks the average squared deviations, the mean squared gaps, during the forecast period. For a concrete example of a time when the differences were particularly visible, we can study the forecast from September 2008. In addition to the repo rate path in the main scenario, the Riksbank usually also analyses two alternative repo rate paths; one that is higher than the one in the main scenario and one that is lower. The mean squared gaps for different measures of inflation and resource utilisation generated by these three interest rate paths in September 2008 are shown in Figure 2. 4  4  See, for instance, Blinder, A. S. (2007), “Central Banking by Committee: Why and How?” European Journal of Political Economy vol. 23, pp. 106–123. BIS central bankers’ speeches  Figure 2. Mean squared gaps September 2008  Source: The Riksbank Note: Red dots show the main scenario, blue dots show the alternative with a higher repo rate path and yellow dots show the alternative with a lower repo rate path. If inflation is measured in terms of the CPIF, that is, the CPI excluding direct effects of interest rates, and if resource utilisation is measured with a gap calculated on the number of hours worked in the economy, one obtains the three dots up on the left-hand side of the figure.
This could mean that the central bank chooses a repo rate path that, while it does not give the lowest squared deviations over the three-year forecast period, is nevertheless judged preferable from a longer-term perspective. For instance, the bank may hold the policy rate higher to try to prevent a credit boom that is feared would cause problems – with large squared deviations – beyond the forecast horizon. A closely-related reason is that the central bank under certain circumstances gives consideration to specific risks when setting interest rates. This is something I personally find to be one of the most important factors missing in the simple analytical framework. This could also be expressed as the central bank holding the policy rate at a higher level to reduce the risk – within or beyond the forecast horizon – that, for instance, a credit boom would continue too long and cause problems. The central bank might also wish to hold the policy rate at a higher level to reduce the risk of inflation expectations rising too high, which could also be problematic. The higher policy rate could give larger deviations during the forecast period, but may nevertheless be preferable as it reduces the risk of a really poor outcome. Framework more difficult to apply with an Executive Board Another circumstance that I perceive as complicating matters with regard to putting the theoretical approach into practice is the fact that there are six of us making the monetary policy decisions.