We study how changes in the steady-state real interest rate (henceforth r*) affect the optimal inflation target in a New Keynesian dynamic stochastic general equilibrium (DSGE) model with trend inflation and a lower bound on the nominal interest rate. In this setup, a lower r* increases the probability of hitting the lower bound. That effect can be counteracted by an increase in the inflation target, but the resulting higher steady-state inflation has a welfare cost in and of itself. We use an estimated DSGE model to quantify that trade-off and determine the implied optimal inflation target, conditional on the monetary policy rule in place before the financial crisis. The relation between r* and the optimal inflation target is downward sloping. While the increase in the optimal inflation rate is in general smaller than the decline in r*, in the currently empirically relevant region the slope of the relation is found to be close to −1. That slope is robust to allowing for parameter uncertainty. Under makeup strategies such as price level targeting, the optimal inflation target is significantly lower and less sensitive to r*.

在具有趋势通胀率和名义利率下限的新凯恩斯主义动态随机一般均衡（DSGE）模型中，我们研究稳态实际利率的变化（henceforth r *）如何影响最佳通胀目标。在此设置中，较低的r *增加了达到下限的可能性。通货膨胀目标的提高可以抵消这种影响，但由此产生的更高的稳态通货膨胀本身具有福利成本。我们使用估计的DSGE模型来量化权衡取舍，并确定隐含的最佳通货膨胀目标，这要视金融危机之前制定的货币政策规则而定。r之间的关系*最佳通胀目标是向下倾斜。尽管最佳通货膨胀率的增长通常小于r *的下降，但在当前经验相关的区域中，该关系的斜率接近-1。该斜率对于允许参数不确定性是鲁棒的。在诸如价格水平目标之类的补充策略下，最佳通货膨胀目标明显较低，并且对r *的敏感性较低。