微观经济学需求与供给曲线

Demand,Supply,andMarketEquilibrium©2007Pearson/PrenticeHallEconomics:Principles,Applications,andTools,5eO’Sullivan•Sheffrin•[e-mail]:均衡chapter©2007Pearson/PrenticeHallEconomics:Principles,Applications,andTools,5eO’Sullivan•Sheffrin•Perez2of39DEMAND,SUPPLY,ANDMARKETEQUILIBRIUM•perfectlycompetitivemarketAmarketwithsomanybuyersandsellersthatnosinglebuyerorsellercanaffectthemarketprice.chapter©2007Pearson/PrenticeHallEconomics:Principles,Applications,andTools,5eO’Sullivan•Sheffrin•Perez3of394.1Hereisalistofthevariablesthataffectanindividualconsumer’sdecision,usingthepizzamarketasanexample:•Thepriceoftheproduct(forexample,thepriceofapizza)•Theconsumer’sincome•Thepriceofsubstitutegoods(forexample,thepricesoftacosorsandwiches)•Thepriceofcomplementarygoods(forexample,thepricesofbeerorlemonade)•Theconsumer’spreferencesortastesandadvertisingthatmayinfluencepreferences•Theconsumer’sexpectationsaboutfutureprices•quantitydemandedTheamountofaproductthatconsumersarewillingandabletobuy.THEDEMANDCURVEchapter©2007Pearson/PrenticeHallEconomics:Principles,Applications,andTools,5eO’Sullivan•Sheffrin•Perez4of39THEDEMANDCURVETheIndividualDemandCurveandtheLawofDemand需求定律4.1FIGURE4.1TheIndividualDemandCurve•individualdemandcurveAcurvethatshowstherelationshipbetweenthepriceofagoodandquantitydemandedbyanindividualconsumer,ceterisparibus.其他条件不变chapter©2007Pearson/PrenticeHallEconomics:Principles,Applications,andTools,5eO’Sullivan•Sheffrin•Perez5of39THEDEMANDCURVETheIndividualDemandCurveandtheLawofDemand4.1•lawofdemandThereisanegativerelationshipbetweenpriceandquantitydemanded,ceterisparibus.•changeinquantitydemandedAchangeinthequantityconsumersarewillingandabletobuywhenthepricechanges;representedgraphicallybymovementalongthedemandcurve.chapter©2007Pearson/PrenticeHallEconomics:Principles,Applications,andTools,5eO’Sullivan•Sheffrin•Perez6of39FromIndividualDemandtoMarketDemand4.1•marketdemandcurveAcurveshowingtherelationshipbetweenpriceandquantitydemandedbyallconsumers,ceterisparibus.FIGURE4.2FromIndividualtoMarketDemandTHEDEMANDCURVEchapter©2007Pearson/PrenticeHallEconomics:Principles,Applications,andTools,5eO’Sullivan•Sheffrin•Perez7of39STARBUCKSGAINSONCHANGESINEXPECTATIONS•Thesalesgrowthwasattributedtoreintroductionofsomepopularproducts,fallinggaspricesprovidingsome“economicrelief,”andcolderweather.•Thecompany’sstockpricerespondedaccordinglytotheincreasedsalesnumbersandclosedup7.6percent.Starbucks,thespecialtycoffeechain,announcedSeptembersalesthatwerehigherthaninvestorsexpected.Thecompany’ssalesgrowthwassixpercenthigherthanthepreviousperiod.Thestreetestimatehadonlyprojectedanincreaseof3.4percent.Howdoesachangeinexpectationsimpactstockprices?Asinvestorsadjustsales(andprofits)expectations,thedemandforStarbucks’stockswillincreaseandisrepresentedbyarightwardshiftinthedemandcurve.Notethatpriceswillmovehigherasaresult.Itisonlythe“unexpected”portionofthesalesannouncementthatwillactuallyshiftthedemandandmoveprice.The“expected”increaseof3.4percentisalreadyfactoredintothepricebyinvestors.ExtraApplication6chapter©2007Pearson/PrenticeHallEconomics:Principles,Applications,andTools,5eO’Sullivan•Sheffrin•Perez8of39Supposeyouaskthemanagerofafirm,“Howmuchofyourproductareyouwillingtoproduceandsell?”Themanager’sdecisionabouthowmuchtoproducedependsonmanyvariables,includingthefollowing,usingpizzaasanexample:•Thepriceoftheproduct(forexample,thepriceperpizza)•Thewagepaidtoworkers•Thepriceofmaterials(forexample,thepriceofdoughandcheese)•Thecostofcapital(forexample,thecostofapizzaoven)•Thestateofproductiontechnology(forexample,theknowledgeusedinmakingpizza)•Producers’expectationsaboutfutureprices•Taxespaidtothegovernmentorsubsidies(paymentsfromthegovernmenttofirmstoproduceaproduct)4.2THESUPPLYCURVE•quantitysuppliedTheamountofaproductthatfirmsarewillingandabletosell.chapter©2007Pearson/PrenticeHallEconomics:Principles,Applications,andTools,5eO’Sullivan•Sheffrin•Perez9of39THESUPPLYCURVE4.2FIGURE4.3TheIndividualSupplyCurveTheIndividualSupplyCurveandtheLawofSupply•individualsupplycurveAcurveshowingtherelationshipbetweenpriceandquantitysuppliedbyasinglefirm,ceterisparibus.chapter©2007Pearson/PrenticeHallEconomics:Principles,Applications,andTools,5eO’Sullivan•Sheffrin•Perez10of39THESUPPLYCURVETheIndividualSupplyCurveandtheLawofSupply4.2•changeinquantitysuppliedAchangeinthequantityfirmsarewillingandabletosellwhenthepricechanges;representedgraphicallybymovementalongthesupplycurve.•minimumsupplypriceThelowestpriceatwhichaproductwillbesupplied.•lawofsupplyThereisapositiverelationshipbetweenpriceandquantitysupplied,ceterisparibus.chapter©2007Pearson/PrenticeHallEconomics:Principles,Applications,andTools,5eO’Sullivan•Sheffrin•Perez11of39THESUPPLYCURVEWhyIstheIndividualSupplyCurvePositivelySloped?4.2FromIndividualSupplytoMarketSupply•marketsupplycurveAcurveshowingtherelationshipbetweenthemarketpriceandquantitysuppliedbyallfirms,ceterisparibus.chapter©2007Pearson/PrenticeHallEconomics:Principles,Applications,andTools,5eO’Sullivan•Sheffr