LearningobjectivesThischapterintroducesyouto(1)theissuesthatmacroeconomistsstudy;(2)thetoolsthatmacroeconomistsuse;(3)someimportantconceptsinmacroeconomicanalysis宏觀經濟學家研究的問題；使用的工具；宏觀經濟分析中的一些重要概念LearningobjectivesThischapte0ImportantissuesinmacroeconomicsWhyaremillionsofpeopleunemployed,evenwhentheeconomyisbooming?Whyarethererecessions?

Canthegovernmentdoanythingtocombatrecessions?Shouldit??為何即使經濟高漲的時候，也有大量勞動力失業？為什么有衰退？政府能做什么？該不該做？Importantissuesinmacroecono1ImportantissuesinmacroeconomicsWhatisthegovernmentbudgetdeficit?Howdoesitaffecttheeconomy?WhydoestheU.S.havesuchahugetradedeficit?Whyaresomanycountriespoor?

Whatpoliciesmighthelpthemgrowoutofpoverty?什么是政府預算赤字（budgetdeficit）？美國為什么有巨額赤字？為什么那么多的國家貧窮？什么樣的政策可以幫助他們擺脫貧困？Importantissuesinmacroecono2U.S.GrossDomesticProduct

inbillionsofchained1996dollarslong-runupwardtrend…GDPU.S.GrossDomesticProduct

i3U.S.GrossDomesticProduct

inbillionsofchained1996dollarsRecessionslongesteconomicexpansiononrecord最長的經濟擴張記錄衰退U.S.GrossDomesticProduct

i4Whylearnmacroeconomics?

為什么學習宏觀經濟學？Themacroeconomyaffectssociety’swell-being（社會福利）.example:Unemploymentandsocialproblems

Eachone-pointincreaseintheu-rate（失業率）isassociatedwith:920moresuicides（自殺者）650morehomicides（殺人者）4000morepeopleadmittedtostatementalinstitutions3300morepeoplesenttostateprisons（監獄）37,000moredeaths（死亡）increasesindomesticviolenceandhomelessness（無家）可歸）例如：失業和社會問題Whylearnmacroeconomics?

為什么學5Whylearnmacroeconomics?Themacroeconomyaffectsyourwell-being.Unemploymentandearningsgrowth每小時工資增長率失業率Whylearnmacroeconomics?Them6Whylearnmacroeconomics?Themacroeconomyaffectsyourwell-being.InterestratesandmortgagepaymentsFora$150,00030-yearmortgage（抵押）:

$9,888$8245.21%$11,520$9606.63%6/21/02annualpaymentmonthlypaymentactualrateon30-yearmortgagedate6/20/03Whylearnmacroeconomics?Them7Whylearnmacroeconomics?Themacroeconomyaffectspolitics¤tevents.Inflationandunemploymentinelectionyearsyear Urate inflationrate elec.outcome1976 7.7% 5.8% Carter(D)1980 7.1% 13.5% Reagan(R)1984 7.5% 4.3% Reagan(R)1988 5.5% 4.1% BushI(R)1992 7.5% 3.0% Clinton(D)1996 5.4% 3.3% Clinton(D)2000 4.0% 3.4% BushII(R)Whylearnmacroeconomics?Them8Economicmodels（經濟模型）…aresimplifiedversionsofamorecomplexrealityirrelevantdetailsarestrippedawayUsedto（1）showtherelationshipsbetweeneconomicvariables（2）explaintheeconomy’sbehavior（3）devisepoliciestoimproveeconomicperformance不相干的細節都被剝離掉了是對真實世界的簡化Economicmodels（經濟模型）…aresimp9Exampleofamodel:

Thesupply&demandfornewcarsexplainsthefactorsthatdeterminethepriceofcarsandthequantitysoldassumesthemarketiscompetitive:eachbuyerandselleristoosmalltoaffectthemarketpriceVariables:Q

d=quantityofcarsthatbuyersdemandQ

s=quantitythatproducerssupplyP=priceofnewcarsY=aggregateincome（外生變量）Ps=priceofsteel(aninput)（外生變量）Exampleofamodel:

Thesupp10Thedemandforcarsshowsthatthequantity

ofcarsconsumersdemand

isrelatedtothepriceofcars

andaggregateincome.Thedemandforcarsshowsthat11Digression:FunctionalnotationGeneralfunctionalnotation

showsonlythatthevariablesarerelated:Alistofthevariables

thataffectQ

dDigression:Functionalnotati12Digression:FunctionalnotationGeneralfunctionalnotation

showsonlythatthevariablesarerelated:Aspecificfunctionalformshows

theprecisequantitativerelationship:Digression:Functionalnotati13Themarketforcars:demandQQuantityofcarsP

Price

ofcarsDThedemandcurveshowstherelationshipbetweenquantitydemandedandprice,otherthingsequal.Themarketforcars:demandQ14Themarketforcars:supplyQQuantityofcarsP

Price

ofcarsDSThesupplycurveshowstherelationshipbetweenquantitysuppliedandprice,otherthingsequal.Themarketforcars:supplyQ15Themarketforcars:equilibriumQQuantityofcarsP

Price

ofcarsSDequilibriumpriceequilibrium

quantityThemarketforcars:equilibr16Theeffectsofanincreaseinincome:D2QQuantityofcarsP

Price

ofcarsSD1Q1P1Anincreaseinincomeincreasesthequantity

ofcarsconsumersdemandateachprice...…whichincreasestheequilibriumpriceandquantity.P2Q2Theeffectsofanincreasein17Theeffectsofasteelpriceincrease:QQuantityofcarsP

Price

ofcarsS1DQ1P1AnincreaseinPsreducesthequantityofcarsproducerssupplyateachprice……whichincreasesthemarketpriceandreducesthequantity.P2Q2S2Ps=priceofsteel(aninput)Theeffectsofasteelpricei18Endogenousvs.exogenousvariables:Thevaluesofendogenousvariables

aredeterminedinthemodel.Thevaluesofexogenousvariables

aredeterminedoutsidethemodel:

themodeltakestheirvalues&behavior

asgiven.Inthemodelofsupply&demandforcars,內生變量對外生變量外生的Y=aggregateincomePs=priceofsteel(aninput)Endogenousvs.exogenousvaria19Nowyoutry:Writedowndemandandsupply

equationsforwirelessphones;

includetwoexogenousvariables

ineachequation.Drawasupply-demandgraph

forwirelessphones.Useyourgraphtoshowhowachangeinoneofyourexogenousvariablesaffectsthemodel’sendogenousvariables.Nowyoutry:Writedowndemand20AmultitudeofmodelsNoonemodelcanaddressalltheissueswecareabout.Forexample,Ifwewanttoknowhow

afallinaggregateincomeaffectsnewcarprices,wecanusetheS/Dmodel（供需模型）fornewcars.Butifwewanttoknowwhyaggregateincomefalls,weneedadifferentmodel.沒有一個模型是萬能的，不同問題需要不同模型。AmultitudeofmodelsNoonemo21AMultitudeofModelsSowewilllearndifferentmodelsforstudyingdifferentissues(e.g.,unemployment,inflation,long-rungrowth).Foreachnewmodel,youshouldkeeptrackof

itsassumptions（它的假定）,whichofitsvariablesareendogenousandwhichareexogenous（變量內生還是外生）,thequestionsitcanhelpusunderstand,andthoseitcannot.AMultitudeofModelsSowewil22Prices:flexibleversusstickyMarketclearing（市場出清）:anassumptionthatpricesareflexibleandadjusttoequatesupplyanddemand.Intheshortrun,manypricesaresticky（粘性的）---

theyadjustonlysluggishly（行動遲緩地）inresponsetosupply/demandimbalances.

Forexample,laborcontractsthatfixthenominalwage

forayearorlongermagazinepricesthatpublisherschange

onlyonceevery3-4yearsPrices:flexibleversusstick23Prices:flexibleversusstickyTheeconomy’sbehaviordependspartlyonwhetherpricesarestickyorflexible:Ifpricesaresticky,thendemandwon’talwaysequalsupply.Thishelpsexplainunemployment(excesssupplyoflabor)theoccasionalinabilityoffirmstosellwhattheyproduce.Longrun:pricesflexible,marketsclear,economybehavesverydifferently

如果價格是粘性的，那么，需求不一定總是等于總供給。Prices:flexibleversusstick24Outlineofthisbook:Introductorymaterial(Chaps.1&2)ClassicalTheory

（古典理論）(Chaps.3to6)

Howtheeconomyworksinthelongrun,whenpricesareflexibleGrowthTheory

(Chaps.7to8)

（經濟增長理論）

ThestandardoflivinganditsgrowthrateovertheverylongrunBusinessCycleTheory

（經濟周期理論(Chaps9to13)

Howtheeconomyworksintheshortrun,whenpricesaresticky）Outlineofthisbook:Introduct25Outlineofthisbook:Policydebates

(Chaps.14to15)

Shouldthegovernmenttrytosmoothbusinesscyclefluctuations?Isthegovernment’sdebt(債務)aproblem?Microeconomicfoundations

(Chaps.16to19)

Insightsfromlookingatthebehaviorofconsumers,firms,andotherissuesfromamicroeconomicperspectiveOutlineofthisbook:Policyde26ChaptersummaryMacroeconomicsisthestudyoftheeconomyasawhole,includinggrowthinincomes,changesintheoveralllevelofprices,theunemploymentrate.Macroeconomistsattempttoexplaintheeconomyandtodevisepoliciestoimproveitsperformance.

1、宏觀經濟研究經濟整體：包括收入增長、價格水平全面變化、失業率；2、解釋經濟并設計政策以改進績效。ChaptersummaryMacroeconomics27ChaptersummaryEconomistsusedifferentmodelstoexaminedifferentissues.（使用數學模型來探討不同問題）Modelswithflexibleprices（易變價格模型）describetheeconomyinthelongrun;modelswithstickyprices（粘性價格模型）describeeconomyintheshortrun.Macroeconomiceventsandperformancearisefrommanymicroeconomictransactions（微觀經濟交易）;somacroeconomicsusesmanyofthetoolsofmicroeconomics（微觀經濟工具）.

ChaptersummaryEconomistsuse28LearningobjectivesThischapterintroducesyouto(1)theissuesthatmacroeconomistsstudy;(2)thetoolsthatmacroeconomistsuse;(3)someimportantconceptsinmacroeconomicanalysis宏觀經濟學家研究的問題；使用的工具；宏觀經濟分析中的一些重要概念LearningobjectivesThischapte29ImportantissuesinmacroeconomicsWhyaremillionsofpeopleunemployed,evenwhentheeconomyisbooming?Whyarethererecessions?

Canthegovernmentdoanythingtocombatrecessions?Shouldit??為何即使經濟高漲的時候，也有大量勞動力失業？為什么有衰退？政府能做什么？該不該做？Importantissuesinmacroecono30ImportantissuesinmacroeconomicsWhatisthegovernmentbudgetdeficit?Howdoesitaffecttheeconomy?WhydoestheU.S.havesuchahugetradedeficit?Whyaresomanycountriespoor?

Whatpoliciesmighthelpthemgrowoutofpoverty?什么是政府預算赤字（budgetdeficit）？美國為什么有巨額赤字？為什么那么多的國家貧窮？什么樣的政策可以幫助他們擺脫貧困？Importantissuesinmacroecono31U.S.GrossDomesticProduct

inbillionsofchained1996dollarslong-runupwardtrend…GDPU.S.GrossDomesticProduct

i32U.S.GrossDomesticProduct

inbillionsofchained1996dollarsRecessionslongesteconomicexpansiononrecord最長的經濟擴張記錄衰退U.S.GrossDomesticProduct

i33Whylearnmacroeconomics?

為什么學習宏觀經濟學？Themacroeconomyaffectssociety’swell-being（社會福利）.example:Unemploymentandsocialproblems

Eachone-pointincreaseintheu-rate（失業率）isassociatedwith:920moresuicides（自殺者）650morehomicides（殺人者）4000morepeopleadmittedtostatementalinstitutions3300morepeoplesenttostateprisons（監獄）37,000moredeaths（死亡）increasesindomesticviolenceandhomelessness（無家）可歸）例如：失業和社會問題Whylearnmacroeconomics?

為什么學34Whylearnmacroeconomics?Themacroeconomyaffectsyourwell-being.Unemploymentandearningsgrowth每小時工資增長率失業率Whylearnmacroeconomics?Them35Whylearnmacroeconomics?Themacroeconomyaffectsyourwell-being.InterestratesandmortgagepaymentsFora$150,00030-yearmortgage（抵押）:

$9,888$8245.21%$11,520$9606.63%6/21/02annualpaymentmonthlypaymentactualrateon30-yearmortgagedate6/20/03Whylearnmacroeconomics?Them36Whylearnmacroeconomics?Themacroeconomyaffectspolitics¤tevents.Inflationandunemploymentinelectionyearsyear Urate inflationrate elec.outcome1976 7.7% 5.8% Carter(D)1980 7.1% 13.5% Reagan(R)1984 7.5% 4.3% Reagan(R)1988 5.5% 4.1% BushI(R)1992 7.5% 3.0% Clinton(D)1996 5.4% 3.3% Clinton(D)2000 4.0% 3.4% BushII(R)Whylearnmacroeconomics?Them37Economicmodels（經濟模型）…aresimplifiedversionsofamorecomplexrealityirrelevantdetailsarestrippedawayUsedto（1）showtherelationshipsbetweeneconomicvariables（2）explaintheeconomy’sbehavior（3）devisepoliciestoimproveeconomicperformance不相干的細節都被剝離掉了是對真實世界的簡化Economicmodels（經濟模型）…aresimp38Exampleofamodel:

Thesupply&demandfornewcarsexplainsthefactorsthatdeterminethepriceofcarsandthequantitysoldassumesthemarketiscompetitive:eachbuyerandselleristoosmalltoaffectthemarketpriceVariables:Q

d=quantityofcarsthatbuyersdemandQ

s=quantitythatproducerssupplyP=priceofnewcarsY=aggregateincome（外生變量）Ps=priceofsteel(aninput)（外生變量）Exampleofamodel:

Thesupp39Thedemandforcarsshowsthatthequantity

ofcarsconsumersdemand

isrelatedtothepriceofcars

andaggregateincome.Thedemandforcarsshowsthat40Digression:FunctionalnotationGeneralfunctionalnotation

showsonlythatthevariablesarerelated:Alistofthevariables

thataffectQ

dDigression:Functionalnotati41Digression:FunctionalnotationGeneralfunctionalnotation

showsonlythatthevariablesarerelated:Aspecificfunctionalformshows

theprecisequantitativerelationship:Digression:Functionalnotati42Themarketforcars:demandQQuantityofcarsP

Price

ofcarsDThedemandcurveshowstherelationshipbetweenquantitydemandedandprice,otherthingsequal.Themarketforcars:demandQ43Themarketforcars:supplyQQuantityofcarsP

Price

ofcarsDSThesupplycurveshowstherelationshipbetweenquantitysuppliedandprice,otherthingsequal.Themarketforcars:supplyQ44Themarketforcars:equilibriumQQuantityofcarsP

Price

ofcarsSDequilibriumpriceequilibrium

quantityThemarketforcars:equilibr45Theeffectsofanincreaseinincome:D2QQuantityofcarsP

Price

ofcarsSD1Q1P1Anincreaseinincomeincreasesthequantity

ofcarsconsumersdemandateachprice...…whichincreasestheequilibriumpriceandquantity.P2Q2Theeffectsofanincreasein46Theeffectsofasteelpriceincrease:QQuantityofcarsP

Price

ofcarsS1DQ1P1AnincreaseinPsreducesthequantityofcarsproducerssupplyateachprice……whichincreasesthemarketpriceandreducesthequantity.P2Q2S2Ps=priceofsteel(aninput)Theeffectsofasteelpricei47Endogenousvs.exogenousvariables:Thevaluesofendogenousvariables

aredeterminedinthemodel.Thevaluesofexogenousvariables

aredeterminedoutsidethemodel:

themodeltakestheirvalues&behavior

asgiven.Inthemodelofsupply&demandforcars,內生變量對外生變量外生的Y=aggregateincomePs=priceofsteel(aninput)Endogenousvs.exogenousvaria48Nowyoutry:Writedowndemandandsupply

equationsforwirelessphones;

includetwoexogenousvariables

ineachequation.Drawasupply-demandgraph

forwirelessphones.Useyourgraphtoshowhowachangeinoneofyourexogenousvariablesaffectsthemodel’sendogenousvariables.Nowyoutry:Writedowndemand49AmultitudeofmodelsNoonemodelcanaddressalltheissueswecareabout.Forexample,Ifwewanttoknowhow

afallinaggregateincomeaffectsnewcarprices,wecanusetheS/Dmodel（供需模型）fornewcars.Butifwewanttoknowwhyaggregateincomefalls,weneedadifferentmodel.沒有一個模型是萬能的，不同問題需要不同模型。AmultitudeofmodelsNoonemo50AMultitudeofModelsSowewilllearndifferentmodelsforstudyingdifferentissues(e.g.,unemployment,inflation,long-rungrowth).Foreachnewmodel,youshouldkeeptrackof

itsassumptions（它的假定）,whichofitsvariablesareendogenousandwhichareexogenous（變量內生還是外生）,thequestionsitcanhelpusunderstand,andthoseitcannot.AMultitudeofModelsSowewil51Prices:flexibleversusstickyMarketclearing（市場出清）:anassumptionthatpricesareflexibleandadjusttoequatesupplyanddemand.Intheshortrun,manypricesaresticky（粘性的）---

theyadjustonlysluggishly（行動遲緩地）inresponsetosupply/demandimbalances.

Forexample,laborcontractsthatfixthenominalwage

forayearorlongermagazinepricesthatpublisherschange

onlyonceevery3-4yearsPrices:flexibleversusstick52Prices:flexibleversusstickyTheeconomy’sbehaviordependspartlyonwhetherpricesarestickyorflexible:Ifpricesaresticky,thendemandwon’talwaysequalsupply.Thishelpsexplainunemployment(excesssupplyoflabor)theoccasi