Monetary Policy, Inflation Stabilization, and Welfare

这个项目涉及货币政策替代规则的分析。要考虑的规则包括设定联邦基金利率的反馈规则的替代规范。联邦基金利率是美国的货币政策工具。虽然研究的数字结果将特别涉及美国的政策选择，但更笼统的结论可能也适用于其他经济体。将受到主要关注的这类规则，使基金利率成为通胀和实体经济活动当前和最近过去演变的函数，以及其自身最近过去的价值的函数。这样的规范包含了最明显地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，该类别中的策略也可以被证明是最优的。需要解决的问题包括，政策对这两个变量的反应合乎需要的程度，只对此类数据做出延迟反应的后果，以及只随着时间推移而不是一次突然行动而逐步调整政策的后果。还将考虑使用额外指标的可能好处，特别是在没有足够及时或准确的直接通货膨胀和产出衡量标准的情况下。在这些其他指标中，正确使用通胀预测将受到特别关注。该项目将在一个小型结构模型的背景下分析替代政策，在该模型中，模型方程是从货物供应者和需求者的明确跨期优化中得出的，因此纳入了前瞻性行为；因此，分析将考虑到对更传统的计量经济学政策评估方法的“卢卡斯批评”。同时，模型参数是基于美国总体时间序列估计的，该模型能够相当详细地模拟美国产出、通胀和利率变化数据的属性。在最近与哈佛大学的胡里奥·罗滕贝格的合作中，已经引入了这种模型的基准版本；但该模型将在本项目下进一步阐述。还将考虑使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大的领域得出对备选假设相对可靠的结论。将从各种角度对替代政策进行评估。将特别强调政策对通货膨胀变化的影响，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变化的影响密切相关)。使用具有优化基础的模型意味着，还可以根据模型结构关系中反映的偏好，根据所实现的私人福利水平来考虑替代政策下的宏观经济绩效。因此，该项目还将本着标准公共财政活动的精神，计算价格水平不稳定造成的“无谓损失”的衡量标准，并根据对美联储可获得的信息和规则可能涉及的复杂程度的各种假设，努力确定在最大限度减少这种损失的意义上最优的政策规则的特征。理论上的无谓损失将被证明在平均通货膨胀率及其变异性方面都在增加，这是因为当价格不是同时变化时，通货膨胀造成的相对价格扭曲；因此，就这些直观标准的结果而言是可取的政策与在福利方面是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.