Monetary Policy, Inflation Stabilization, and Welfare

这个项目涉及对货币政策的可选规则的分析。要考虑的规则包括设定联邦基金利率（美国货币政策工具）的反馈规则的替代规范。虽然研究的数字结果将特别针对美国的政策选择，但更普遍的结论可能也适用于其他经济体。将受到主要关注的一类规则将使基金利率成为当前和最近过去通货膨胀和实际经济活动演变的函数，以及它自己最近过去的价值。这样的规范包含了最明显影响当前美国政策的两类变量，并允许考虑一系列受欢迎的政策建议。至少在某些简单的假设下，该类中的策略也可以被证明是最优的。需要解决的问题包括政策对这两个变量作出反应的可取程度，只对这些数据作出延迟反应的后果，以及只随时间逐渐调整政策而不是突然调整政策的后果。还将考虑到使用其他指标可能带来的好处，特别是在没有足够及时或准确的通货膨胀和产出的直接衡量标准的情况下。在这些其他指标中，适当使用通货膨胀预测将受到特别关注。该项目将在一个小型结构模型的范围内分析备选政策，其中模型方程是从货物的供应者和需求者的明确跨期优化推导出来的，因此纳入前瞻性行为；因此，分析将考虑到对更传统的计量经济政策评估方法的“卢卡斯批判”。同时，模型参数是根据美国累计时间序列估计的，该模型能够相当详细地模拟美国数据在产出、通货膨胀和利率变化方面的特性。最近，哈佛大学的胡里奥·罗滕伯格（Julio Rotemberg）提出了这种模型的一个基准版本；但该模型将在本项目下进一步细化。还将考虑用该模型获得的结果与其他小型结构模型的结果的可比性，以便在模型不确定性特别显著的领域中得出对替代假设相对稳健的结论。备选政策将从不同的角度进行评估。将特别强调政策对通货膨胀可变性的影响，以及对平均通货膨胀率的影响（事实证明，这与政策对短期利率可变性的影响密切相关）。使用具有优化基础的模型意味着，根据模型结构关系中反映的偏好，也可以根据所获得的私人福利水平来考虑替代政策下的宏观经济表现。因此，该项目还将以标准公共财政实践的精神，计算价格水平不稳定导致的“无谓损失”的度量，并寻求在对美联储可获得的信息的各种假设以及规则可能涉及的复杂程度下，从最小化这种损失的意义上来说，最优政策规则的特征。理论上的无谓损失将显示在平均通货膨胀率及其可变性方面都在增加，因为当价格并非全部同时变化时，通货膨胀造成的相对价格扭曲；因此，就这些直观标准的后果而言，可取的政策与那些在福利方面最优的政策密切相关。

This project is concerned with the analysis of alternative rules for monetary policy. The rules to be considered consist of alternative specifications of feedback rules for setting the Federal funds rate, the instrument of monetary policy in the U.S. While the numerical results of the study will address U.S. policy choice in particular, the more general conclusions are likely to be of application to other economies as well. The class of rules that will receive primary attention makes the funds rate a function of the current and recent past evolution of inflation and real economic activity, and of its own recent past values. Such a specification incorporates the two types of variables that most clearly affect current U.S. policy, and allows consideration of a range of popular policy proposals as well. Under at least certain simple assumptions, a policy within that class can also be shown to be optimal. Issues to be addressed include the degree to which it is desirable for policy to respond to these two variables, the consequences of responding to such data only with a delay, and the consequences of adjusting policy only gradually over time rather than in one sudden move. Consideration will also be given to the possible advantages of the use of additional indicators, especially when direct measures of inflation and output are not available that are sufficiently timely or accurate. Among such other indicators, the proper use of inflation forecasts will receive particular attention. The project will analyze alternative policies in the context of a small structural model in which the model equations are derived from explicit intertemporal optimization on the part of the suppliers and demanders of goods, and as a result incorporate forward-looking behavior; the analysis will thus take account of the `Lucas critique` of more traditional methods of econometric policy evaluation. At the same time, the model parameters are estimated on the basis of U.S. aggregate time series, and the model is able to mimic the properties of U.S. data on output, inflation and interest rate variations in considerable detail. A benchmark version of such a model has been introduced in recent work with Julio Rotemberg of Harvard; but the model will be further elaborated under this project. Comparability of the results obtained with this model with those of other small structural models will also be considered, in attempt to reach conclusions that are relatively robust to alternative assumptions in areas where model uncertainty is especially significant. Alternative policies will be evaluated from a variety of points of view. Particular emphasis will be given to the consequences of policy for the variability of inflation, and for the average rate of inflation (which turns out to be closely related to a policy's consequences for the variability of short term interest rates). The use of a model with optimizing foundations means that it is also possible to consider macroeconomic performance under alternative policies in terms of the level of private welfare attained, according to the preferences reflected in the structural relations of the model. Thus the project will also compute measures of the `deadweight loss` resulting from price level instability, in the spirit of standard public finance exercises, and seek to characterize the policy rules that are optimal in the sense of minimizing this loss, under various assumptions about the information available to the Fed, and the degree of complexity that the rule may involve. Theoretical deadweight loss will be shown to be increasing in both the average rate of inflation and its variability, owing to the relative price distortions caused by inflation when prices are not all changed simultaneously; hence policies that are desirable in terms of their consequences for these intuitive criteria are closely related to those that are optimal in welfare terms.