经济学（微观）（英文版原书第7版）课件 第1章　经济学：基础与模型

EconomicsSeventhEditionChapter1Economics:FoundationsandModelsCopyright©2019,2017,2015PearsonEducation,Inc.AllRightsReserved.ChapterOutline1.1

ThreeKeyEconomicIdeas1.2

TheEconomicProblemThatEverySocietyMustSolve1.3

EconomicModels1.4

MicroeconomicsandMacroeconomics1.5EconomicSkillsandEconomicsasaCareer1.6

APreviewofImportantEconomicTermsAppendix

UsingGraphsandFormulasWhatisthisclassabout?Peoplemakechoicesastheytrytoattaintheirgoals.Choicesarenecessarybecauseweliveinaworldofscarcity.Scarcity:Asituationinwhichunlimitedwantsexceedthelimitedresourcesavailabletofulfillthosewants.Economicsisthestudyofthechoicespeoplemaketoattaintheirgoals,giventheirscarceresources.Economistsstudythesechoicesusingeconomicmodels,simplifiedversionsofrealityusedtoanalyzereal-worldeconomicsituations.Sometypical“economics”questionsWewilllearnhowtoanswerquestionslikethese:Howarethepricesofgoodsandservicesdetermined?Whyhavehealthcarecostsrisensorapidly?Whydofirmsengageininternationaltrade,andhowdogovernmentpoliciesaffectinternationaltrade?Whydoesgovernmentcontrolthepricesofsomegoodsandservices,andwhataretheeffectsofthosecontrols?1.1ThreeKeyEconomicIdeasExplainthesethreekeyeconomicideas:Peoplearerational,peoplerespondtoeconomicincentives,andoptimaldecisionsaremadeatthemargin.Economicagentsinteractwithoneanotherinmarkets.Market:Agroupofbuyersandsellersofagoodorserviceandtheinstitutionorarrangementbywhichtheycometogethertotrade.Inanalyzingmarkets,wegenerallyassume:PeoplearerationalPeoplerespondtoeconomicincentivesOptimaldecisionsaremadeatthemargin1.PeopleAreRationalEconomistsgenerallyassumethatpeoplearerational,usingallavailableinformationtoachievetheirgoals.Rationalconsumersandfirmsweighthebenefitsandcostsofeachactionandtrytomakethebestdecisionpossible.Example:Appledoesn’trandomlychoosethepriceofitsiPhones;itchoosestheprice(s)thatitthinkswillbemostprofitable.2.PeopleRespondtoEconomicIncentivesAsincentiveschange,sodotheactionsthatpeoplewilltake.Example:ChangesinseveralfactorshaveresultedinincreasedobesityinAmericansoverthelastcoupleofdecades,including:DecreasesinthepriceoffastfoodrelativetohealthfulfoodImprovednon-activeentertainmentoptionsIncreasedavailabilityofhealthcareandinsurance,protectingpeopleagainsttheconsequencesoftheiractions3.OptimalDecisionsAreMadeattheMarginWhilesomedecisionsareall-or-nothing,mostdecisionsinvolvedoingalittlemoreoralittlelessofsomething.Example:ShouldyouwatchanextrahourofTVorstudyinstead?Economiststhinkaboutdecisionslikethisintermsofthemarginalcostandbenefit(MCandMB):theadditionalcostorbenefitassociatedwithasmallamountextraofsomeaction.ComparingMCandMBisknownasmarginalanalysis.ApplytheConcept:HealthInsuranceandObesity(1of2)ObesityisrisinginAmerica,forvariousreasons.Isoneofthosereasonshealthinsurance?ApplytheConcept:HealthInsuranceandObesity(2of2)Peoplewithhealthinsurancehavelessincentivetostayhealthythanpeoplewithouthealthinsurance.Holdingconstantotherfactorslikeage,gender,andincome,researchshowspeoplewithhealthinsurancearemorelikelytobeobese.Theyarerespondingtoeconomicincentives.1.2TheEconomicProblemThatEverySocietyMustSolveDiscusshowaneconomyanswersthesequestions:Whatgoodsandserviceswillbeproduced?Howwillthegoodsandservicesbeproduced?Whowillreceivethegoodsandservicesproduced?Inaworldofscarcity,wehavelimitedeconomicresourcestosatisfyourdesires.Thereforewefacetrade-offs.Trade-off:Theideathat,becauseofscarcity,producingmoreofonegoodorservicemeansproducinglessofanothergoodorservice.1.WhatGoodsandServicesWillBeProduced?Individuals,firms,andgovernmentsmustdecideonthegoodsandservicesthatshouldbeproduced.Anincreaseintheproductionofonegoodrequiresthereductionintheproductionofsomeothergood.Thisisatrade-off,resultingfromthescarcityofproductiveresources.Thehighest-valuedalternativegivenupinordertoengageinsomeactivityisknownastheopportunitycost.Example:theopportunitycostofincreasedfundingforspaceexplorationmightbegivinguptheopportunitytofundcancerresearch.2.HowWilltheGoodsandServicesBeProduced?Afirmmighthaveseveraldifferentmethodsforproducingitsgoodsandservices.Example#1:AmusicproducercanmakeasongsoundgoodbyHiringagreatsingerandusingstandardproductiontechniques;HiringamediocresingerandusingAuto-Tunetocorrecttheinaccuracies.Example#2:Asthecostofmanufacturinglaborchanges,afirmmightrespondbyChangingitsproductiontechniquetoonethatemploysmoremachinesandfewerworkersMovingitsfactorytoalocationwithcheaperlabor3.WhoWillReceivetheGoodsandServicesProduced?ThewaywearemostfamiliarwithintheUnitedStatesisthatpeoplewithhigherincomesobtainmoregoodsandservices.Changesintaxandwelfarepolicieschangethedistributionofincome,thoughpeopleoftendisagreeabouttheextenttowhichthis“redistribution”isdesirable.TypesofEconomiesCentrallyplannedeconomy:Aneconomyinwhichthegovernmentdecideshoweconomicresourceswillbeallocated.Marketeconomy:

Aneconomyinwhichthedecisionsofhouseholdsandfirmsinteractinginmarketsallocateeconomicresources.Mixedeconomy:Aneconomyinwhichmosteconomicdecisionsresultfromtheinteractionofbuyersandsellersinmarketsbutinwhichthegovernmentplaysasignificantroleintheallocationofresources.WhichofthesebestdescribestheUnitedStatestoday?EfficiencyofMarketEconomiesMarketeconomiestendtobemoreefficientthancentrally-plannedeconomies.Marketeconomiespromote:Productiveefficiency,asituationinwhichagoodorserviceisproducedatthelowestpossiblecost;andAllocativeefficiency,astateoftheeconomyinwhichproductionisinaccordancewithconsumerpreferences;inparticular,everygoodorserviceisproduceduptothepointwherethelastunitprovidesamarginalbenefittosocietyequaltothemarginalcostofproducingit.SourceofEconomicEfficiencyProductiveefficiencycomesaboutbecauseofcompetition.Allocativeefficiencyarisesduetovoluntaryexchange.Voluntaryexchange:Asituationthatoccursinmarketswhenboththebuyerandthesellerofaproductaremadebetteroffbythetransaction.Eachtransactionthattakesplaceimprovesthewell-beingofthebuyerandseller;transactionscontinueuntilnofurtherimprovementcantakeplace.CaveatsaboutMarketEconomiesMarketsmaynotresultinfullyefficientoutcomes.Forexample:PeoplemightnotimmediatelydothingsinthemostefficientwayGovernmentsmightinterferewithmarketoutcomesMarketoutcomesmightignorethedesiresofpeoplewhoarenotinvolvedintransactions–ex:pollutionMarketEconomiesandEquityEconomicallyefficientoutcomesarenotnecessarilydesirable.Lessefficientoutcomesmaybemorefairorequitable.Equity:Thefairdistributionofeconomicbenefits.Animportanttrade-offforagovernmentisthatbetweenefficiencyandequity.Example:Ifwetaxincome,peoplemightworklessoropenfewerbusinesses,butthosetaxreceiptscanfundprogramsthataidthepoor.1.3EconomicModelsExplainhoweconomistsusemodelstoanalyzeeconomiceventsandgovernmentpolicies.Economistsdevelopeconomicmodelstoanalyzereal-worldissues.Buildinganeconomicmodeloftenfollowsthesesteps:Decideontheassumptionstouse.Formulateatestablehypothesis.Useeconomicdatatotestthehypothesis.Revisethemodelifitfailstoexplaintheeconomicdatawell.Retaintherevisedmodeltohelpanswersimilareconomicquestionsinthefuture.ImportantFeaturesofEconomicModelsAssumptionsandsimplifications:everymodelneedstheminordertobeuseful.Testability:goodmodelsgeneratetestablepredictions,whichcanbeverifiedordisprovenusingdata.Economicvariables:somethingmeasurablethatcanhavedifferentvalues,suchasthenumberofpeopleemployedinmanufacturing.FormingHypothesesinEconomicModelsInaneconomicmodel,ahypothesisisastatementaboutaneconomicvariablethatmaybeeithercorrectorincorrect.Ex:TheincreaseduseofindustrialrobotsandinformationtechnologyinU.S.factorieshasresultedinadeclineinmanufacturingemployment.Mosteconomichypothesesareaboutcausalrelationships.TestingHypothesesinEconomicModelsAftercollectingtherelevantdata,economistsusestatisticalmethodstoevaluatethehypotheses.Itisoftendifficulttoestablishwhetheraneffectiscausal.Ex:Employmentinmanufacturingdiddeclineatthesametimethattheuseofrobotsincreased,butthatdoesn’tproveonecausedtheother.Economistsacceptanduseaneconomicmodelifitleadstohypothesesthatareconfirmed(ornotrejected)bystatisticalanalysis.Newinformationmayrejectpreviously-believedhypotheses.PositiveandNormativeAnalysisEconomiststrytomimicnaturalscientistsbyusingthescientificmethod.Buteconomicsisasocialscience;studyingthebehaviorofpeopleisoftentricky.Whenanalyzinghumanbehavior,wecanperform:Positiveanalysis:analysisconcernedwithwhatis.Normativeanalysis:analysisconcernedwithwhatoughttobe.Economistsmostlyperformpositiveanalysis.Governmentpolicymakershaveincreasinglyreliedoneconomicanalysis.ApplytheConcept:WhatCanEconomicsContributetotheDebateoverTariffs?Governmentscanimposetariffs(taxesonimports)toraiserevenueordiscourageimports.Economictheorycanidentifythelikelywinnersandlosersfromaparticulartariff.Economicanalysiscanusemodelsanddatatoestimatethedollaramountsgainedbythewinnersandlostbythelosers.Typically,thelossesoutweighthegains,soeconomistsgenerallydiscouragetariffs.Butpolicymakersmayplacehighervalueonthewell-beingofsomegroups—anormativejudgment.1.4MicroeconomicsandMacroeconomicsDistinguishbetweenmicroeconomicsandmacroeconomics.Microeconomicsisthestudyofhowhouseholdsandfirmsmakechoices,howtheyinteractinmarkets,andhowthegovernmentattemptstoinfluencetheirchoices.Macroeconomicsisthestudyoftheeconomyasawhole,includingtopicssuchasinflation,unemployment,andeconomicgrowth.Table1.1IssuesinMicroeconomicsandMacroeconomicsExamplesofMicroeconomicIssuesExamplesofMacroeconomicIssuesHowconsumersreacttochangesinproductpricesHowfirmsdecidewhatpricestochargefortheproductstheysellWhichgovernmentpolicywouldmostefficientlyreduceobesityThecostsandbenefitsofapprovingthesaleofanewprescriptiondrugThemostefficientwaytoreduceairpollutionWhyeconomiesexperienceperiodsofrecessionandincreasingunemploymentWhy,overthelongrun,someeconomieshavegrownmuchfasterthanothersWhatdeterminestheinflationrateWhatdeterminesthevalueoftheU.SdollarinexchangeforothercurrenciesWhethergovernmentinterventioncanreducetheseverityofrecessions1.5EconomicSkillsandEconomicsasaCareerDescribeeconomicsasacareerandthekeyskillsyoucangainfromstudyingeconomics.Whenbuyingahouse,ahomeinspectorcandescribeproblemsthehousehas,andadvisehowtofixtheproblems,andthelikelycost.Similarly,aneconomistcandescribehowindividuals,businesses,andgovernmentsmakechoices,andwhattheconsequencesofthosechoiceswouldbe;andadviseonhowbetterdecisionscanbemade.SomeTypicalEconomistRolesinBusiness,Government,orNonprofitOrganizationsForecastthedemandforelectriccarsoverthenext10yearsForecastfuturevaluesofinterestratesEvaluatewhethernewstoreswouldbeprofitableEvaluatetheeffectonamarketfromaproposedmergerForecastregionaltrendsinemploymentandproductionInterpretmonetarypolicyforwideaudiencesAnalyzetheeffectivenessofadevelopmentprograminalow-incomecountry1.6APreviewofImportantEconomicTermsDefineimportanteconomicterms.Likeallfieldsofstudy,economicsusestermsorjargonwithspecific,precisemeanings.Sometimesthesetermswillbeusedinwaysthatdifferevenfromcloselyrelateddisciplines.Examples:Technology:theprocessesafirmusestoproducegoodsandservicesCapital:manufacturedgoodsthatareusedtoproduceothergoodsandservicesPaycloseattentiontotermsdefinedinclassandinthetextbook!Appendix:UsingGraphsandFormulasUsegraphsandformulastoanalyzeeconomicsituations.Amapisasimplifiedmodelofreality,showingessentialdetailsonly.Economicmodels,withfeatureslikegraphsandformulas,canhelpusunderstandeconomicsituationsjustlikeamaphelpsustounderstandthegeographiclayoutofacity.Figure1A.1BarGraphsandPieChartsTheleftpanelshowsabargraphofmarketsharedatafortheU.S.automobileindustry;marketshareisrepresentedbytheheightofthebar.Therightpanelshowsapiechartofthesamedata;marketshareisrepresentedbythesizeofthe“sliceofthepie”.Figure1A.2Time-SeriesGraphsBothpanelspresenttime-seriesgraphsofFordMotorCompany’sworldwidesalesduringeachyearfrom2005to2015.Therightpanelhasatruncatedscaleontheverticalaxis,whiletheleftpaneldoesnot.Asaresult,thefluctuationsinFord’ssalesappearsmallerintheleftpanelthantherightone.Figure1A.3PlottingPriceandQuantityPointsinaGraphThefigureshowsatwo-dimensionalgridonwhichwemeasurethepriceofpizzaalongtheverticalaxis(ory-axis)andthequantityofpizzasoldperweekalongthehorizontalaxis(orx-axis).Eachpointonthegridrepresentsoneofthepriceandquantitycombinationslistedinthetable.Byconnectingthepointswithaline,wecanbetterillustratetherelationshipbetweenthetwovariables.Figure1A.4CalculatingtheSlopeofaLine(1of2)Wecancalculatetheslopeofalineasthechangeinthevalueofthevariableonthey-axisdividedbythechangeinthevalueofthevariableonthex-axis.Becausetheslopeofastraightlineisconstant,wecanuseanytwopointsinthefiguretocalculatetheslopeoftheline.Figure1A.4CalculatingtheSlopeofaLine(2of2)Forexample,whenthepriceofpizzadecreasesfrom$14to$12,thequantityofpizzademandedincreasesfrom55perweekto65perweek.So,theslopeofthislineequals−2dividedby10,or−0.2.Figure1A.5ShowingThreeVariablesonaGraph(1of3)Thedemandcurveforpizzashowstherelationshipbetweenthepriceofpizzasandthequantityofpizzasdemanded,holdingconstantotherfactorsthatmightaffectthewillingnessofconsumerstobuypizza.Figure1A.5ShowingThreeVariablesonaGraph(2of3)Ifthepriceofpizzais$14(pointA),anincreaseinthepriceofhamburgersfrom$1.50to$2.00increasesthequantityofpizzasdemandedfrom55to60perweek(pointB)andshiftsustoDemandcurve2.Figure1A.5ShowingThreeVariablesonaGraph(3of3)Or,ifwestartonDemandcurve1andthepriceofpizzais$12(pointC),adecreaseinthepriceofhamburgersfrom$1.50to$1.00decreasesthequantityofpizzademandedfrom65to60perweek(pointD)andshiftsustoDemandcurve3.Figure1A.6GraphingthePositiveRelationshipbetweenIncomeandConsumptionInapositiverelationshipbetweentwoeconomicvariables,asonevariableincreases,theothervariablealsoincreases.Inanegativerelationship,asonevariableincreases,theotherdecreases.Thisfigureshowsthepositiverelationshipbetweendisposablepersonalincomeandconsumptionspending.Figure1A.7DeterminingCauseandEffectUsinggraphstodrawconclusionsaboutcauseandeffectishazardous.Forexample,inpanel(a),asthenumberoffiresinfireplacesincreases,thenumberofleavesontreesfalls;butthefiresdon’tcausetheleavestofall.Inpanel(b),asthenumberoflawnmowersbeingusedincreases,sodoestherateatwhichgrassgrows.AreGraphsofEconomicRelationshipsAlwaysStraightLines?Therelationshipbetweentwovariablesislinearwhenitcanberepresentedbyastraightline.Feweconomicrelationshipsareactuallylinear.Howeverlinearapproximationsaresimplertouseandareoften“goodenough”inmodeling.Figure1A.8TheSlopeofaNonlinearCurve(panel(a))Anon-linearcurvehasdifferentslopesatdif