鲁迪格·多恩布什-宏观经济学（第十三版）IPPTChap018.pptVIP

PolicyChapter #18Copyright ? 2014 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. IntroductionIn this chapter we examine how policymakers formulate appropriate policy measuresConsider:TimingUncertaintyHow individuals will respond to specific policiesRole of credibilityMonetary or fiscal policy, or a mixDifferent policy instrumentsDifferent intermediate and ultimate targets18-2 Lags in the Effects of PolicySuppose the economy is at full employment:Affected by a negative aggregate demand disturbance ? reduces the equilibrium level of income below full employmentNo advance warning of disturbance ? no policy action taken in anticipation of its occurrencePolicymakers must decide:Should they respond to the disturbance?If so, how should they respond?18-3 Lags in the Effects of PolicyIs the disturbance permanent (or persistent) or temporary?Figure 18-1 illustrates a temporary aggregate demand shockA one period reduction in consumption ? best policy is to do nothing at allToday’s policy actions take time to have an effect ? would hit economy after back at full-employment level, driving it away from the optimal level18-4 Lags in the Effects of Policy Inside Lags: the time period it takes to undertake a policy actionRecognition Lag: the period that elapses between the time a disturbance occurs and the time the policymakers recognize that action is requiredLag is negative if the disturbance is predicted and appropriate policy actions considered before it occurs (Ex. Increase money supply prior Christmas)Lag is typically positive18-5Policymaking is a process:Takes time to recognize and implement a policy actionTakes time for an action to work its way through the economyEach step involves delays or lags:Inside lagsRecognition lagsDecision lagsAction lagsOutside lags Lags in the Effects of Policy 18-6Inside Lags: the time period it takes to undertake a policy actionDecision Lag: the delay betwe