中級宏觀經濟學第十七章課件

中級宏觀經濟學第十七章課件17-1ExpectationsandDecisions:TakingStockExpectations,Consumption,andInvestmentDecisionsExpectationsaffectconsumptionandinvestmentdecisions,bothdirectlyandthroughassetprices.ExpectationsandSpending:

TheChannelsFigure17-1217-1ExpectationsandDecisioNotefromFigure17-1:Anincreaseincurrentandexpectedfutureafter-taxreallaborincome,oradecreaseincurrentandexpectedfuturerealinterestrates,increaseshumanwealthandleadstoanincreaseinconsumption.Anincreaseincurrentandexpectedfuturerealdividends,oradecreaseincurrentandexpectedfuturerealinterestrates,increasesstockpriceswhichleadstoanincreaseinnonhumanwealthandanincreaseinconsumption.17-1ExpectationsandDecisions:TakingStockExpectations,Consumption,andInvestmentDecisions3NotefromFigure17-1:17-1ENotefromFigure17-1:Adecreaseincurrentandexpectedfuturenominalinterestratesleadstoanincreaseinbondprices,whichleadstoanincreaseinnonhumanwealthandanincreaseinconsumption.Anincreaseincurrentandexpectedfuturerealafter-taxprofits,oradecreaseincurrentandexpectedfuturerealinterestrates,increasesthepresentvalueofrealafter-taxprofits,whichleadstoanincreaseininvestment.17-1ExpectationsandDecisions:TakingStockExpectations,Consumption,andInvestmentDecisions4NotefromFigure17-1:17-1EConsumptionandinvestmentdependonexpectationsofthefuture.Totakeintoaccounttheeffectofexpectations,wedothefollowing:Earlier,theISrelationwas:

Defineaggregateprivatespendingorsimply,privatespending,A,as:RewritetheISrelationas:17-1ExpectationsandDecisions:TakingStockExpectationsandtheISRelation5ConsumptionandinvestmentdepGivenandandincorporatingtheroleofexpectations,then:*Primesdenotefuturevalues,andedenotesexpectedvalues.Thepositiveandnegativesignsexplainhow:17-1ExpectationsandDecisions:TakingStockExpectationsandtheISRelation6Givenandandincorporatingthe17-1ExpectationsandDecisions:TakingStockExpectationsandtheISRelationGivenexpectations,adecreaseintherealinterestrateleadstoasmallincreaseinoutput:TheIScurveissteeplydownwardsloping.IncreasesingovernmentspendingorinexpectedfutureoutputshifttheIScurvetotheright.Increasesintaxes,inexpectedfuturetaxes,orintheexpectedfuturerealinterestrateshifttheIScurvetotheleft.TheNewISCurveFigure17-2717-1ExpectationsandDecisioThenewIScurveissteep,whichmeansthatalargedecreaseinthecurrentinterestrateislikelytohaveonly

asmalleffectonequilibriumincome,fortworeasons:Adecreaseinthecurrentrealinterestratedoesnothavemucheffectonspendingiffutureexpectedratesarenotlikelytobeloweraswell.

Themultiplierislikelytobesmall.Ifchangesinincomearenotexpectedtolast,theywillhavea

limitedeffectonconsumptionandinvestment.17-1ExpectationsandDecisions:TakingStockExpectationsandtheISRelation8ThenewIScurveissteep,whiChangesinotherthanYandr,shifttheIScurve:ChangesinT(currenttaxes)orG(currentgovernmentspending)shifttheIScurveChangesinexpectedfuturevariablesalsoshifttheIScurve.17-1ExpectationsandDecisions:TakingStockExpectationsandtheISRelation9ChangesinTheLMrelationisnotmodifiedbecausetheopportunitycostofholdingmoneytodaydependsonthecurrentnominalinterestrate,notontheexpectednominalinterestrateoneyearfromnow.TheinterestratethatenterstheLMrelationisthecurrentnominalinterestrate.17-1ExpectationsandDecisions:TakingStockTheLMRelationRevisited10TheLMrelationisnotmodifietheMissionoftheFED“TheCongresshasentrustedtheFederalReservewithgreatresponsibilities.Ineveryphaseofourworkanddecisionmaking,weconsiderthewell-beingoftheAmericanpeopleandtheprosperityofournation.”——ChairJanetL.Yellen11theMissionoftheFEDWhentheFedexpandedthemoneysupply,“the”interestratewentdown,andspendingincreased.Therearemanyinterestrates,keepthesetwodistinctionsinmind:Thedistinctionbetweenthenominalinterestrateandtherealinterestrate.

Thedistinctionbetweencurrentandexpectedfutureinterestrates.17-2MonetaryPolicy,Expectations,andOutput12WhentheFedexpandedthemoneDecreasingthecurrentnominalinterestrateieffectsthecurrentandexpectedfuturerealinterestratesdependingontwofactors:Whethertheincreaseinthemoneysupplyleadsfinancialmarketstorevisetheirexpectationsofthefuturenominalinterestrate,i’e.Whethertheincreaseinthemoneysupplyleadsfinancialmarketstorevisetheirexpectationsofbothcurrentandfutureinflationπe

andπ’e.17-2MonetaryPolicy,Expectations,andOutputFromtheShortNominalRatetoCurrent

andExpectedRealRates13Decreasingthecurrentnominal17-2MonetaryPolicy,Expectations,andOutputFromtheShortNominalRatetoCurrent

andExpectedRealRatesTheIScurveissteeplydownwardsloping.Otherthingsequal,achangeinthecurrentinterestratehasasmalleffectonoutput.TheLMcurveisupwardsloping.TheequilibriumisattheintersectionoftheISandLMcurves.TheNewIS–LMFigure17-31417-2MonetaryPolicy,Expecta17-2MonetaryPolicy,Expectations,andOutputMonetaryPolicyRevisitedTheeffectsofmonetarypolicyonoutputdependverymuchonwhetherandhowmonetarypolicyaffectsexpectations.TheEffectsofanExpansionaryMonetaryPolicyFigure17-41517-2MonetaryPolicy,ExpectaTheeffectsofmonetarypolicydependcruciallyonitseffectonexpectations:Ifamonetaryexpansionleadsfinancialinvestors,firms,andconsumerstorevisetheirexpectationsoffutureinterestratesandoutput,thentheeffectsofthemonetaryexpansiononoutputmaybeverylarge.Butifexpectationsremainunchanged,theeffectsofthemonetaryexpansiononoutputwillbesmall.17-2MonetaryPolicy,Expectations,andOutputMonetaryPolicyRevisitedPeopleformexpectationsaboutthefuturebyassessingthelikelycourseoffutureexpectedpolicyandthenworkingouttheimplicationsoffutureactivity.Economistsrefertoexpectationsformedinaforward-lookingmannerasrational

expectations16TheeffectsofmonetarypolicyRationalExpectationsUntilthe1970s,macroeconomiststhoughtofexpectationsas:Animalspirits-theKeynesiantreatmentofexpectations,whichconsidersthemimportantbutunexplained.Backward-lookingrules—eitherstaticoradaptiveexpectations.Theassumptionofrationalexpectationsisoneofthe

mostimportantdevelopmentsinmacroeconomicsinthe

last25years.17RationalExpectationsUntiltheRecalltheconclusionswereachedinthecoreabouttheeffectsofabudgetdeficitreduction:Inthelongrun,areductioninthebudgetdeficitislikelytobebeneficialfortheeconomy.Inthemediumrun,alowerbudgetdeficitimplieshighersavingandhigherinvestment.Inthelongrun,higherinvestmenttranslatesintohighercapitalandthushigheroutput.Intheshortrun,however,areductioninthebudgetdeficit,unlessitisoffsetbyamonetaryexpansion,leadstolowerspendingandtoacontractioninoutput.17-3DeficitReduction,Expectations,

andOutput18RecalltheconclusionswereacLet’sreviewwhatwelearnedabouttheeffectsofadeficitreductioninthemediumrunandthelongrun:Inthemediumrun,adeficitreductionhasnoeffectonoutput.Itleads,however,toalowerinterestrateandtohigherinvestment.Inthelongrun,higherinvestmentleadstoahighercapitalstock,andtoahigherlevelofoutput.17-3DeficitReduction,Expectations,

andOutputTheRoleofExpectationsabouttheFuture19Let’sreviewwhatwelearneda17-3DeficitReduction,Expectations,

andOutputBacktotheCurrentPeriodWhenaccountistakenofitseffectonexpectations,thedecreaseingovernmentspendingneednotleadtoadecreaseinoutput.TheEffectsofaDeficitReductiononCurrentOutputFigure17-52017-3DeficitReduction,ExpecDeficitreductionmayactuallyincreasespendingandoutput,evenintheshortrun,ifpeopletakeintoaccountthefuturebeneficialeffectsofdeficitreduction.Inresponsetotheannouncementofdeficitreduction,Currentspendinggoesdown—theIScurveshiftstotheleft.Expectedfutureoutputgoesup—theIScurveshiftstotheright.Andtheinterestrategoesdown—theIScurveshiftstotheright.17-3DeficitReduction,Expectations,

andOutputBacktotheCurrentPeriod21DeficitreductionmayactuallySmallcutsingovernmentspendingandlargeexpectedcutsinthefuturewillcauseoutputtoincreasemoreinthecurrentperiod—aconceptknownasbackloading.Backloading,however,mayleadtoaproblemwiththecredibilityofthedeficitreductionprogram—leavingmostofthereductionforthefuture,notthepresent.Thegovernmentmustplayadelicatebalancingact:enoughcutsinthecurrentperiodtoshowacommitmenttodeficitreductionandenoughcutslefttothefuturetoreducetheadverseeffectsontheeconomyintheshortrun.17-3DeficitReduction,Expectations,

andOutputBacktotheCurrentPeriod22SmallcutsingovernmentspendCanaBudgetDeficitReductionLeadtoan

OutputExpansion?Irelandinthe1980sTable1FiscalandOtherMacroeconomicIndicators,Ireland,1981to1984

and1986to1989198119821983198419861987198819891Budgetdeficit(%ofGDP)-13.0-13.4-11.4-9.5-10.7-8.6-4.5-1.82Outputgrowthrate(%)3.32.3-0.24.4-5.83Unemploymentrate(%)9.511.013.515.017.116.916.315.14Householdsavingrate(%ofdisposableincome)17.919.618.118.415.712.911.012.623CanaBudgetDeficitReductionTosummarize,thechangeinoutputasaresultofdeficitreductiondependson:ThecredibilityoftheprogramThetimingoftheprogramThecompositionoftheprogramThestateofgovernmentfinancesinthefirstplace.17-3DeficitReduction,Expectations,

andOutputBacktotheCurrentPeriod24Tosummarize,thechangeinouKeyTermsaggregateprivatespending,orprivatespendinganimalspiritsadaptiveexpectationsrationalexpectationsbackloadingcredibility25KeyTermsaggregateprivatespe中級宏觀經濟學第十七章課件17-1ExpectationsandDecisions:TakingStockExpectations,Consumption,andInvestmentDecisionsExpectationsaffectconsumptionandinvestmentdecisions,bothdirectlyandthroughassetprices.ExpectationsandSpending:

TheChannelsFigure17-12717-1ExpectationsandDecisioNotefromFigure17-1:Anincreaseincurrentandexpectedfutureafter-taxreallaborincome,oradecreaseincurrentandexpectedfuturerealinterestrates,increaseshumanwealthandleadstoanincreaseinconsumption.Anincreaseincurrentandexpectedfuturerealdividends,oradecreaseincurrentandexpectedfuturerealinterestrates,increasesstockpriceswhichleadstoanincreaseinnonhumanwealthandanincreaseinconsumption.17-1ExpectationsandDecisions:TakingStockExpectations,Consumption,andInvestmentDecisions28NotefromFigure17-1:17-1ENotefromFigure17-1:Adecreaseincurrentandexpectedfuturenominalinterestratesleadstoanincreaseinbondprices,whichleadstoanincreaseinnonhumanwealthandanincreaseinconsumption.Anincreaseincurrentandexpectedfuturerealafter-taxprofits,oradecreaseincurrentandexpectedfuturerealinterestrates,increasesthepresentvalueofrealafter-taxprofits,whichleadstoanincreaseininvestment.17-1ExpectationsandDecisions:TakingStockExpectations,Consumption,andInvestmentDecisions29NotefromFigure17-1:17-1EConsumptionandinvestmentdependonexpectationsofthefuture.Totakeintoaccounttheeffectofexpectations,wedothefollowing:Earlier,theISrelationwas:

Defineaggregateprivatespendingorsimply,privatespending,A,as:RewritetheISrelationas:17-1ExpectationsandDecisions:TakingStockExpectationsandtheISRelation30ConsumptionandinvestmentdepGivenandandincorporatingtheroleofexpectations,then:*Primesdenotefuturevalues,andedenotesexpectedvalues.Thepositiveandnegativesignsexplainhow:17-1ExpectationsandDecisions:TakingStockExpectationsandtheISRelation31Givenandandincorporatingthe17-1ExpectationsandDecisions:TakingStockExpectationsandtheISRelationGivenexpectations,adecreaseintherealinterestrateleadstoasmallincreaseinoutput:TheIScurveissteeplydownwardsloping.IncreasesingovernmentspendingorinexpectedfutureoutputshifttheIScurvetotheright.Increasesintaxes,inexpectedfuturetaxes,orintheexpectedfuturerealinterestrateshifttheIScurvetotheleft.TheNewISCurveFigure17-23217-1ExpectationsandDecisioThenewIScurveissteep,whichmeansthatalargedecreaseinthecurrentinterestrateislikelytohaveonly

asmalleffectonequilibriumincome,fortworeasons:Adecreaseinthecurrentrealinterestratedoesnothavemucheffectonspendingiffutureexpectedratesarenotlikelytobeloweraswell.

Themultiplierislikelytobesmall.Ifchangesinincomearenotexpectedtolast,theywillhavea

limitedeffectonconsumptionandinvestment.17-1ExpectationsandDecisions:TakingStockExpectationsandtheISRelation33ThenewIScurveissteep,whiChangesinotherthanYandr,shifttheIScurve:ChangesinT(currenttaxes)orG(currentgovernmentspending)shifttheIScurveChangesinexpectedfuturevariablesalsoshifttheIScurve.17-1ExpectationsandDecisions:TakingStockExpectationsandtheISRelation34ChangesinTheLMrelationisnotmodifiedbecausetheopportunitycostofholdingmoneytodaydependsonthecurrentnominalinterestrate,notontheexpectednominalinterestrateoneyearfromnow.TheinterestratethatenterstheLMrelationisthecurrentnominalinterestrate.17-1ExpectationsandDecisions:TakingStockTheLMRelationRevisited35TheLMrelationisnotmodifietheMissionoftheFED“TheCongresshasentrustedtheFederalReservewithgreatresponsibilities.Ineveryphaseofourworkanddecisionmaking,weconsiderthewell-beingoftheAmericanpeopleandtheprosperityofournation.”——ChairJanetL.Yellen36theMissionoftheFEDWhentheFedexpandedthemoneysupply,“the”interestratewentdown,andspendingincreased.Therearemanyinterestrates,keepthesetwodistinctionsinmind:Thedistinctionbetweenthenominalinterestrateandtherealinterestrate.

Thedistinctionbetweencurrentandexpectedfutureinterestrates.17-2MonetaryPolicy,Expectations,andOutput37WhentheFedexpandedthemoneDecreasingthecurrentnominalinterestrateieffectsthecurrentandexpectedfuturerealinterestratesdependingontwofactors:Whethertheincreaseinthemoneysupplyleadsfinancialmarketstorevisetheirexpectationsofthefuturenominalinterestrate,i’e.Whethertheincreaseinthemoneysupplyleadsfinancialmarketstorevisetheirexpectationsofbothcurrentandfutureinflationπe

andπ’e.17-2MonetaryPolicy,Expectations,andOutputFromtheShortNominalRatetoCurrent

andExpectedRealRates38Decreasingthecurrentnominal17-2MonetaryPolicy,Expectations,andOutputFromtheShortNominalRatetoCurrent

andExpectedRealRatesTheIScurveissteeplydownwardsloping.Otherthingsequal,achangeinthecurrentinterestratehasasmalleffectonoutput.TheLMcurveisupwardsloping.TheequilibriumisattheintersectionoftheISandLMcurves.TheNewIS–LMFigure17-33917-2MonetaryPolicy,Expecta17-2MonetaryPolicy,Expectations,andOutputMonetaryPolicyRevisitedTheeffectsofmonetarypolicyonoutputdependverymuchonwhetherandhowmonetarypolicyaffectsexpectations.TheEffectsofanExpansionaryMonetaryPolicyFigure17-44017-2MonetaryPolicy,ExpectaTheeffectsofmonetarypolicydependcruciallyonitseffectonexpectations:Ifamonetaryexpansionleadsfinancialinvestors,firms,andconsumerstorevisetheirexpectationsoffutureinterestratesandoutput,thentheeffectsofthemonetaryexpansiononoutputmaybeverylarge.Butifexpectationsremainunchanged,theeffectsofthemonetaryexpansiononoutputwillbesmall.17-2MonetaryPolicy,Expectations,andOutputMonetaryPolicyRevisitedPeopleformexpectationsaboutthefuturebyassessingthelikelycourseoffutureexpectedpolicyandthenworkingouttheimplicationsoffutureactivity.Economistsrefertoexpectationsformedinaforward-lookingmannerasrational

expectations41TheeffectsofmonetarypolicyRationalExpectationsUntilthe1970s,macroeconomiststhoughtofexpectationsas:Animalspirits-theKeynesiantreatmentofexpectations,whichconsidersthemimportantbutunexplained.Backward-lookingrules—eitherstaticoradaptiveexpectations.Theassumptionofrationalexpectationsisoneofthe

mostimportantdevelopmentsinmacroeconomicsinthe

last25years.42RationalExpectationsUntiltheRecalltheconclusionswereachedinthecoreabouttheeffectsofabudgetdeficitreduction:Inthelongrun,areductioninthebudgetdeficitislikelytobebeneficialfortheeconomy.Inthemediumrun,alowerbudgetdeficitimplieshighersavingandhigherinvestment.Inthelongrun,higherinvestmenttranslatesintohighercapitalandthushigheroutput.Intheshortrun,however,areductioninthebudgetdeficit,unlessitisoffsetbyamonetaryexpansion,leadstolowerspendingandtoacontractioninoutput.17-3DeficitReduction,Expectations,

andOutput43RecalltheconclusionswereacLet’sreviewwhatwelearnedabouttheeffectsofadeficitreductioninthemediumrunandthelongrun:Inthemediumrun,adeficitreductionhasnoeffectonoutput.Itleads,however,toalowerinterestrateandtohigherinvestment.Inthelongrun,higherinvestmentleadstoahighercapitalstock,andtoahigherlevelofoutput.17-3DeficitReduction,Expectations,

andOutputTheRoleofExpectationsabouttheFuture44Let’sreviewwhatwelearneda17-3DeficitReduction,Expectations,

andOutputBacktotheCurrentPeriodWhenaccountistakenofitseffectonexpectations,thedecreaseingovernmentspendingneednotleadtoadecreaseinoutput.TheEffectsofaDeficitReductiononCurrentOutputFigure17-54517-3DeficitReduction,ExpecDeficitreductionmayactuallyincreasespendingandoutput,evenintheshortrun,if