宏观经济学课件

Copyright©2004South-Western35TheShort-RunTradeoff(权衡)betweenInflationandUnemploymentCopyright©2004South-WesternUnemploymentandInflation•Thenaturalrateofunemploymentdependsonvariousfeaturesofthelabormarket.•Examplesincludeminimum-wagelaws,themarketpowerofunions,theroleofefficiencywages,andtheeffectivenessofjobsearch.•Theinflationratedependsprimarilyongrowthinthequantityofmoney,controlledbytheFed.Copyright©2004South-WesternUnemploymentandInflation•Societyfacesashort-runtradeoffbetweenunemploymentandinflation.•Ifpolicymakersexpandaggregatedemand,theycanlowerunemployment,butonlyatthecostofhigherinflation.•Iftheycontractaggregatedemand,theycanlowerinflation,butatthecostoftemporarilyhigherunemployment.Copyright©2004South-Western35.1THEPHILLIPSCURVE•ThePhillipscurveillustratestheshort-runrelationshipbetweeninflationandunemployment.Figure1ThePhillipsCurveUnemploymentRate(percent)0InflationRate(percentperyear)Phillipscurve4B67A2Copyright©2004South-WesternCopyright©2004South-WesternAggregateDemand,AggregateSupply,andthePhillipsCurve•ThePhillipscurveshowstheshort-runcombinations(结合)ofunemploymentandinflationthatariseasshiftsintheaggregatedemandcurvemovetheeconomyalongtheshort-runaggregatesupplycurve.Copyright©2004South-WesternAggregateDemand,AggregateSupply,andthePhillipsCurve•Thegreatertheaggregatedemandforgoodsandservices,thegreateristheeconomy’soutput,andthehigheristheoverallpricelevel.•Ahigherlevelofoutputresultsinalowerlevelofunemployment.Figure2HowthePhillipsCurveisRelatedtoAggregateDemandandAggregateSupplyQuantityofOutput0Short-runaggregatesupply(a)TheModelofAggregateDemandandAggregateSupplyUnemploymentRate(percent)0InflationRate(percentperyear)PriceLevel(b)ThePhillipsCurvePhillipscurveLowaggregatedemandHighaggregatedemand(outputis8,000)B46(outputis7,500)A728,000(unemploymentis4%)106B(unemploymentis7%)7,500102ACopyright©2004South-WesternCopyright©2004South-Western35.2SHIFTSINTHEPHILLIPSCURVE:THEROLEOFEXPECTATIONS•ThePhillipscurveseemstoofferpolicymakersamenuofpossibleinflationandunemploymentoutcomes.Copyright©2004South-WesternTheLong-RunPhillipsCurve•Inthe1960s,FriedmanandPhelpsconcludedthatinflationandunemploymentareunrelatedinthelongrun.•Asaresult,thelong-runPhillipscurveisverticalatthenaturalrateofunemployment.•Monetarypolicycouldbeeffectiveintheshortrunbutnotinthelongrun.Figure3TheLong-RunPhillipsCurveUnemploymentRate0NaturalrateofunemploymentInflationRateLong-runPhillipscurveBHighinflationLowinflationA2....butunemploymentremainsatitsnaturalrateinthelongrun.1.WhentheFedincreasesthegrowthrateofthemoneysupply,therateofinflationincreases...Copyright©2004South-WesternFigure4HowthePhillipsCurveisRelatedtoAggregateDemandandAggregateSupplyQuantityofOutputNaturalrateofoutputNaturalrateofunemployment0PriceLevelPAggregatedemand,ADLong-runaggregatesupplyLong-runPhillipscurve(a)TheModelofAggregateDemandandAggregateSupplyUnemploymentRate0InflationRate(b)ThePhillipsCurve2....raisesthepricelevel...1.Anincreaseinthemoneysupplyincreasesaggregatedemand...AAD2BA4....butleavesoutputandunemploymentattheirnaturalrates.3....andincreasestheinflationrate...P2BCopyright©2004South-WesternCopyright©2004South-WesternExpectationsandtheShort-RunPhillipsCurve•Expectedinflationmeasureshowmuchpeopleexpecttheoverallpriceleveltochange.Copyright©2004South-WesternExpectationsandtheShort-RunPhillipsCurve•Inthelongrun,expectedinflationadjuststochangesinactualinflation.•TheFed’sabilitytocreateunexpectedinflationexistsonlyintheshortrun.•Oncepeopleanticipateinflation,theonlywaytogetunemploymentbelowthenaturalrateisforactualinflationtobeabovetheanticipatedrate.Copyright©2004South-Western•Thisequationrelatestheunemploymentratetothenaturalrateofunemployment,actualinflation,andexpectedinflation.ExpectationsandtheShort-RunPhillipsCurveNaturalrateofunemployment-aActualinflationExpectedinflationUnemploymentRate=Figure5HowExpectedInflationShiftstheShort-RunPhillipsCurveUnemploymentRate0NaturalrateofunemploymentInflationRateLong-runPhillipscurveShort-runPhillipscurvewithhighexpectedinflationShort-runPhillipscurvewithlowexpectedinflation1.Expansionarypolicymovestheeconomyupalongtheshort-runPhillipscurve...2....butinthelongrun,expectedinflationrises,andtheshort-runPhillipscurveshiftstotheright.CBACopyright©2004South-WesternCopyright©2004South-WesternTheNaturalExperimentfortheNatural-RateHypothesis•Theviewthatunemploymenteventuallyreturnstoitsnaturalrate,regardlessoftherateofinflation,iscalledthenatural-ratehypothesis.•Historicalobservationssupportthenatural-ratehypothesis.Copyright©2004South-WesternTheNaturalExperimentfortheNaturalRateHypothesis•TheconceptofastablePhillipscurvebrokedownintheintheearly’70s.•Duringthe’70sand’80s,theeconomyexperiencedhighinflationandhighunemploymentsimultaneously.Figure6ThePhillipsCurveinthe1960s123456789100246810UnemploymentRate(percent)InflationRate(percentperyear)19681966196119621963196719651964Copyright©2004South-WesternFigure7TheBreakdownofthePhillipsCurve123456789100246810UnemploymentRate(percent)InflationRate(percentper