An economy that switches between high and low growth regimes creates incentives for the monetary authority to change the parameters in its simple rule. As lower growth tends to produce lower real interest rates, the monetary authority has an incentive to increase the inflation target and increase the degree of inertia in setting rates in an attempt to keep the nominal rate away from the zero lower bound. An optimal simple rule therefore responds to permanently lower growth by slightly increasing both the inflation target and inertia; focusing solely on the inflation target ignores a key margin of adjustment. With repeated growth rate regime switches, an optimal simple rule that switches at the same time internalizes both the direct effects of growth regime change and the indirect expectation effects generated by switching in policy. The switching rule improves economic outcomes relative to a constant rule. A constant rule may be preferred if the monetary authority attempts a switching rule but implements the wrong rule with high enough frequency.

在高增长和低增长机制之间切换的经济体会激励货币当局改变其简单规则中的参数。由于较低的增长往往会导致较低的实际利率，货币当局有动机提高通胀目标并增加设定利率的惯性程度，以试图使名义利率远离零下限。因此，一个最优的简单规则通过略微增加通胀目标和惯性来应对永久性较低的增长；只关注通胀目标会忽略一个关键的调整幅度。通过反复的增长率制度转换，同时转换的最优简单规则内化了增长制度改变的直接影响和政策转换产生的间接预期影响。相对于恒定规则，转换规则改善了经济结果。如果货币当局尝试转换规则但以足够高的频率实施错误规则，则可能更喜欢恒定规则。