曼昆第10版课件mankiw10e-lecture-slides-ch01

TheScienceofMacroeconomicsMacroeconomicsN.GregoryMankiw©2019WorthPublishers,allrightsreservedINTHISCHAPTER,YOUWILLLEARN:AbouttheissuesmacroeconomistsstudyAboutthetoolsmacroeconomistsuseSomeimportantconceptsinmacroeconomicanalysisImportantissuesinmacroeconomicsPart1Macroeconomics—thestudyoftheeconomyasawhole—addressesmanytopicalissues,suchas:Whatcausesrecessions?Whatis“governmentstimulus,”andwhymightithelp?Howcanproblemsinthehousingmarketspreadtotherestoftheeconomy?Whatisthegovernmentbudgetdeficit?Howdoesitaffectworkers,consumers,businesses,andtaxpayers?ImportantissuesinmacroeconomicsPart2Macroeconomics—thestudyoftheeconomyasawhole—addressesmanytopicalissues,suchas:Whydoesthecostoflivingkeeprising?Whyaresomanycountriespoor?Whatpoliciesmighthelpthemgrowoutofpoverty?Whatisthetradedeficit?Howdoesitaffectacountry’swell-being?U.S.realGDPpercapita(2009dollars)(1of2)U.S.realGDPpercapita(2009dollars)(2of2)U.S.unemploymentrate(%oflaborforce)Economicmodels…aresimplifiedversionsofmorecomplexrealitieswithirrelevantdetailsstrippedaway…areusedto:showrelationshipsbetweenvariablesexplaintheeconomy’sbehaviordevisepoliciestoimproveeconomicperformanceExampleofamodel:SupplyanddemandfornewcarsShowshowvariouseventsaffectthepriceandquantityofcarsAssumesthemarketiscompetitive:eachbuyerandselleristoosmalltoaffectthemarketpriceVariablesQd=quantityofcarsthatbuyersdemandQs=quantityofcarsthatproducerssupplyP=priceofnewcarsY=aggregateincomePs=priceofsteel(aninput)ThedemandforcarsDemandequation:Qd=D(P,Y)ShowsthatthequantityofcarsconsumersdemandisrelatedtothepriceofcarsandaggregateincomeDigression:FunctionalnotationGeneralfunctionalnotation

showsonlythatthevariablesarerelated.Aspecificfunctionalformshowstheprecisequantitativerelationship.Example:

D(P,Y)=60–10P+2YThemarketforcars:DemandDemandequation:Qd=D(P,Y)Thedemandcurveshowstherelationshipbetweenquantitydemandedandprice,otherthingsequal.Themarketforcars:SupplySupplyequation:Qs=S(P,PS)Thesupplycurve

showstherelationshipbetweenquantitysuppliedandprice,otherthingsequal.Themarketforcars:EquilibriumTheeffectsofanincreaseinincomeDemandequation:Qd=D(P,Y)Anincreaseinincomeincreasesthequantity

ofcarsconsumersdemandateachprice……whichincreasestheequilibriumpriceandquantity.TheeffectsofasteelpriceincreaseSupplyequation:Qs=S(P,PS)AnincreaseinPs

reducesthequantityofcarsproducerssupplyateachprice……whichincreasesthemarketpriceandreducesthequantity.Endogenousvs.exogenousvariablesThevaluesofendogenous

variables

aredeterminedinthemodel.Thevaluesofexogenous

variablesaredeterminedoutsidethemodel:themodeltakestheirvaluesandbehaviors

asgiven.Inthemodelofsupplyanddemandforcars,endogenousvariables:P,Qd,Qsexogenousvariables:Y,PsNOWYOUTRY

SupplyanddemandWritedowndemandandsupplyequationsforsmartphones,includetwoexogenousvariablesineachequation.Drawasupply–demandgraphforsmartphonesandidentifytheequilibriumpriceandquantity.Useyourgraphtoshowhowachangeinoneofyourexogenousvariablesaffectsthemodel’sendogenousvariables.Theuseofmultiplemodels,part1Nosinglemodelcanaddressalltheissueswecareabout.Forexample,oursupply–demandmodelofthecarmarket…cantellushowafallinaggregateincomeaffectspriceandquantityofcarscannottelluswhyaggregateincomefallsTheuseofmultiplemodels,part2Wewilllearndifferentmodelsforstudyingdifferentissues(e.g.,unemployment,inflation,long-rungrowth).Foreachnewmodel,youshouldkeeptrackof:itsassumptionswhichvariablesareendogenousandwhichareexogenousthequestionsitcanhelpusunderstandandthoseitcannotPrices:Flexiblevs.sticky,part1Marketclearing:Anassumptionthatpricesareflexibleandadjusttoequatesupplyanddemand.Intheshortrun,manypricesaresticky—adjustsluggishlyinresponsetochangesinsupplyordemand.Forexample:manylaborcontractsfixthenominalwageforayearorlongermanymagazinepublisherschangepricesonlyonceevery3to4yearsPrices:Flexiblevs.sticky,part2Theeconomy’sbehaviordependspartlyonwhetherpricesarestickyorflexible:Ifpricesaresticky(shortrun),demandmaynotequalsupply,whichexplains:unemployment(excesssupplyoflabor)whyfirmscannotalwayssellallthegoodstheyproduceIfpricesareflexible(longrun),marketsclear,andtheeconomybehavesverydifferently.Outlineofthisbook(1of2)Introductorymaterial(Chapters1,2)Classicaltheory(Chapters3–7)

Howtheeconomyworksinthelongrun,whenpricesareflexibleGrowththeory(Chapters8,9)

ThestandardoflivinganditsgrowthrateovertheverylongrunBusinesscycletheory(Chapters10–14)

Howtheeconomyworksintheshortrun,whenpricesarestickyOutlineofthisbook(2of2)Macroeconomictheory(Chapters15–17)

Macroeconomicdynamics,modelsofconsumerbehavior,theoriesoffirms’investmentdecisionsMacroeconomicpolicy(Chapters18–19)

Stabilizationpolicy,governmentdebtanddeficits,financialcri