中级宏观经济学课件第一章

LearningobjectivesThischapterintroducesyoutotheissuesmacroeconomistsstudythetoolsmacroeconomistsusesomeimportantconceptsinmacroeconomicanalysisImportantissuesinmacroeconomicsWhydoesthecostoflivingkeeprising?Whyaremillionsofpeopleunemployed,evenwhentheeconomyisbooming?Whyarethererecessions?

Canthegovernmentdoanythingtocombatrecessions?Shouldit??ImportantissuesinmacroeconomicsWhatisthegovernmentbudgetdeficit?Howdoesitaffecttheeconomy?WhydoestheU.S.havesuchahugetradedeficit?Whyaresomanycountriespoor?

Whatpoliciesmighthelpthemgrowoutofpoverty?U.S.GrossDomesticProduct

inbillionsofchained1996dollarslong-runupwardtrend…U.S.GrossDomesticProduct

inbillionsofchained1996dollarsRecessionslongesteconomicexpansiononrecordWhylearnmacroeconomics?Themacroeconomyaffectssociety’swell-being.example:

UnemploymentandsocialproblemsUnemploymentandsocialproblemsEachone-pointincreaseinthe

unemploymentrateisassociatedwith:920moresuicides（自杀）650morehomicides（杀人）4000morepeopleadmittedtostatementalinstitutions（精神病院）3300morepeoplesenttostateprisons37,000moredeathsincreasesindomesticviolenceandhomelessnessWhylearnmacroeconomics?Themacroeconomyaffectssociety’swell-being.example:

UnemploymentandsocialproblemsThemacroeconomyaffectsyourwell-being.example1:

Unemploymentandearningsgrowthexample2:

InterestratesandmortgagepaymentsUnemploymentandearningsgrowthInterestratesandmortgagepaymentsFora$150,00030-yearmortgage:$11,782$9816.84%Dec2001$12,771$10647.65%Dec2000annualpaymentmonthlypaymentactualrateon30-yearmortgagedateWhylearnmacroeconomics?Themacroeconomyaffectssociety’swell-being.example:

UnemploymentandsocialproblemsThemacroeconomyaffectsyourwell-being.example1:

Unemploymentandearningsgrowthexample2:

InterestratesandmortgagepaymentsThemacroeconomyaffectspolitics¤tevents.example:

InflationandunemploymentinelectionyearsInflationandUnemploymentinElectionYearsyear 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)Economicmodels…aresimpliedversionsofamorecomplexrealityirrelevantdetailsarestrippedawayUsedtoshowtherelationshipsbetweeneconomicvariablesexplaintheeconomy’sbehaviordevisepoliciestoimproveeconomicperformanceExampleofamodel:

Thesupply&demandfornewcarsexplainsthefactorsthatdeterminethepriceofcarsandthequantitysold.assumesthemarketiscompetitive:eachbuyerandselleristoosmalltoaffectthemarketpriceVariables:Q

d=quantityofcarsthatbuyersdemandQ

s=quantitythatproducerssupplyP=priceofnewcarsY=aggregateincomePs=priceofsteel(aninput)Thedemandforcarsshowsthatthequantity

ofcarsconsumersdemand

isrelatedtothepriceofcars

andaggregateincome.Digression:FunctionalnotationGeneralfunctionalnotationshowsonlythatthevariablesarerelated:Alistofthevariables

thataffectQ

dDigression(枝节话):FunctionalnotationGeneralfunctionalnotationshowsonlythatthevariablesarerelated:Aspecificfunctionalformshowstheprecise（准确地）quantitativerelationship:Themarketforcars:demandQQuantityofcarsP

Price

ofcarsDThedemandcurveshowstherelationshipbetweenquantitydemandedandprice,otherthingsequal.Themarketforcars:supplyQQuantityofcarsP

Price

ofcarsDSThesupplycurveshowstherelationshipbetweenquantitysuppliedandprice,otherthingsequal.Themarketforcars:equilibriumQQuantityofcarsP

Price

ofcarsSDequilibriumpriceequilibrium

quantityTheeffectsofanincreaseinincome:D2QQuantityofcarsP

Price

ofcarsSD1Q1P1Anincreaseinincomeincreasesthequantity

ofcarsconsumersdemandateachprice……whichincreasestheequilibriumpriceandquantity.P2Q2Theeffectsofasteelpriceincrease:QQuantityofcarsP

Price

ofcarsS1DQ1P1AnincreaseinPsreducesthequantityofcarsproducerssupplyateachprice……whichincreasesthemarketpriceandreducesthequantity.P2Q2S2Endogenousvs.exogenous

variables:Thevaluesofendogenousvariables（内生变量）

aredeterminedinthemodel.Thevaluesofexogenousvariables（外生变量）

aredeterminedoutsidethemodel:

themodeltakestheirvalues&behavior

asgiven.Inthemodelofsupply&demandforcars,Nowyoutry:Writedowndemandandsupply

equationsforwirelessphones;

includetwoexogenousvariables

ineachequation.Drawasupply-demandgraph

forwirelessphones.Useyourgraphtoshowhowachangeinoneofyourexogenousvariablesaffectsthemodel’sendogenousvariables.AMultitude（大量）ofModelsNoonemodelcanaddressalltheissueswecareabout.Forexample,Ifwewanttoknowhowafallinaggregateincomeaffectsnewcarprices,wecanusetheS/Dmodelfornewcars.Butifwewanttoknowwhyaggregateincomefalls,weneedadifferentmodel.AMultitudeofModelsSowewilllearndifferentmodelsforstudyingdifferentissues(e.g.unemployment,inflation,long-rungrowth).Foreachnewmodel,youshouldkeeptrackofitsassumptions,whichofitsvariablesareendogenousandwhichareexogenous,thequestionsitcanhelpusunderstand,andthoseitcannot.Prices:Flexible（灵活的）VersusSticky（粘性的）Marketclearing:anassumptionthatpricesareflexibleandadjusttoequatesupplyanddemand.Intheshortrun,manypricesaresticky---theyadjustonlysluggishly(缓慢地)inresponsetosupply/demandimbalances.

Forexample,laborcontractsthatfixthenominalwageforayearorlongermagazinepricesthatpublisherschangeonlyonceevery3-4yearsPrices:FlexibleVersusStickyTheeconomy’sbehaviordependspartlyonwhetherpricesarestickyorflexible:Ifpricesaresticky,thendemandwon’talwaysequalsupply.Thishelpsexplainunemployment(excesssupplyoflabor)theoccasionalinabilityoffirmstosellwhattheyproduceLongrun:pricesflexible,marketsclear,economybehavesverydifferently.Outlineofthisbook:Introductorymaterial(chaps.1&2)ClassicalTheory

(chaps.3-6)

Howtheeconomyworksinthelongrun,whenpricesareflexibleGrowthTheory

(chaps.7-8)

ThestandardoflivinganditsgrowthrateovertheverylongrunBusinessCycleTheory

(chaps9-13)

Howtheeconomyworksintheshortrun,whenpricesaresticky.Outlineofthisbook:Policydebates

(Chaps.14-15)

Shouldthegovernmenttrytosmoothbusinesscyclefluctuations?Isthegovernment’s