曼昆《经济学原理》6供给与需求政府管制

Copyright©2004South-Western6Supply,Demand,andGovernmentPoliciesCopyright©2004South-Western/ThomsonLearningSupply,Demand,andGovernmentPolicies•Inafree,unregulatedmarketsystem,marketforcesestablishequilibriumpricesandexchangequantities.•在自由的、不存在规制的市场中，市场力量建立均衡价格和数量。•Whileequilibriumconditionsmaybeefficient,itmaybetruethatnoteveryoneissatisfied.•均衡可能是有效率的，但并不是每个人对这种自由市场调整的结果都感到满意。•Oneoftherolesofeconomistsistousetheirtheoriestoassistinthedevelopmentofpolicies.•经济学家的一个职责就是运用理论帮助政府制定政策。Copyright©2004South-Western/ThomsonLearningCONTROLSONPRICES价格控制•Areusuallyenactedwhenpolicymakersbelievethemarketpriceisunfairtobuyersorsellers.•Resultingovernment-createdpriceceilingsandpricefloors.•当政策制定者认为，对卖者或者买者而言，价格不公时，会采取控制价格的措施。比如，价格上限、价格下限。Copyright©2004South-Western/ThomsonLearningCONTROLSONPRICES•PriceCeiling价格上限•Alegalmaximumonthepriceatwhichagoodcanbesold.法定最高价格•PriceFloor价格下限•Alegalminimumonthepriceatwhichagoodcanbesold.法定最低价格Copyright©2004South-Western/ThomsonLearningHowPriceCeilingsAffectMarketOutcomes价格上限如何影响市场结果•Twooutcomesarepossiblewhenthegovernmentimposesapriceceiling:•政府制定价格上限会有两种可能的结果：•Thepriceceilingisnotbindingifsetabovetheequilibriumprice.•如果制定的价格高于均衡价格，那么价格上限没有限制作用。•Thepriceceilingisbindingifsetbelowtheequilibriumprice,leadingtoashortage.•如果制定的价格上限低于均衡价格，那么价格价格上限有限制作用，会导致短缺。Figure1AMarketwithaPriceCeiling(a)APriceCeilingThatIsNotBindingQuantityofIce-CreamCones0PriceofIce-CreamConeEquilibriumquantity$4PriceceilingEquilibriumpriceDemandSupply3100制定的价格高于均衡价格Figure1AMarketwithaPriceCeilingCopyright©2003Southwestern/ThomsonLearning(b)APriceCeilingThatIsBindingQuantityofIce-CreamCones0PriceofIce-CreamConeDemandSupply2PriceceilingShortage75Quantitysupplied125QuantitydemandedEquilibriumprice$3制定的价格低于均衡价格Copyright©2004South-Western/ThomsonLearningHowPriceCeilingsAffectMarketOutcomes价格上限如何影响市场结果•EffectsofPriceCeilings：价格上限的作用•Abindingpriceceilingcreates•ShortagesbecauseQDQS.短缺•Example:Gasolineshortageofthe1970s•Nonpricerationing非价格配给•Examples:Longlines,discriminationbyseller•当政府对竞争市场实行限制性价格上限时，会产生物品的短缺，卖者在大量的买者中配给稀缺物品。这种配给制很少是合意的。排长队无效率，根据卖者偏好的歧视既无效率，也不公平。Copyright©2004South-Western/ThomsonLearning•In1973,OPECraisedthepriceofcrudeoilinworldmarkets.Crudeoilisthemajorinputingasoline,sothehigheroilpricesreducedthesupplyofgasoline.•Whatwasresponsibleforthelonggaslines?CASESTUDY:LinesattheGasPump•Economistsblamegovernmentregulationsthatlimitedthepriceoilcompaniescouldchargeforgasoline.Copyright©2004South-Western/ThomsonLearning经典案例：加油站前排长队•1973年石油输出国组织提高原油价格，原油是生产汽油的主要投入，结果导致生产汽油的成本上升，汽油供给减少，加油站前排起了长队。•多数人将原因归咎于欧佩克，如果他们不提高原油价格，就不会出现汽油的短缺。•经济学家将其归咎于限制石油公司对汽油可收取价格的政府管制。最终，美国对汽油价格的价格管制撤销了。立法者终于明白，他们必须为美国人排队等候买汽油而浪费时间承担部分责任。Figure2TheMarketforGasolinewithaPriceCeilingCopyright©2003Southwestern/ThomsonLearning(a)ThePriceCeilingonGasolineIsNotBindingQuantityofGasoline0PriceofGasoline1.Initially,thepriceceilingisnotbinding...PriceceilingDemandSupply,S1P1Q1Figure2TheMarketforGasolinewithaPriceCeilingCopyright©2003Southwestern/ThomsonLearning(b)ThePriceCeilingonGasolineIsBindingQuantityofGasoline0PriceofGasolineDemandS1S2PriceceilingQS4....resultinginashortage.3....thepriceceilingbecomesbinding...2....butwhensupplyfalls...P2QDP1Q1Copyright©2004South-Western/ThomsonLearningCASESTUDY:RentControlintheShortRunandLongRun短期、长期租金控制•Rentcontrolsareceilingsplacedontherentsthatlandlordsmaychargetheirtenants.•Thegoalofrentcontrolpolicyistohelpthepoorbymakinghousingmoreaffordable.•Oneeconomistcalledrentcontrol“thebestwaytodestroyacity,otherthanbombing.”•许多城市，地方政府规定了房东能够向房客收取的租金的上限。目的是为了帮助穷人能够租的起房子。经济学家认为，这是一种极端没有效率的方法。“除了轰炸以外，毁灭一个城市的最好办法”。Figure3RentControlintheShortRunandintheLongRunCopyright©2003Southwestern/ThomsonLearning(a)RentControlintheShortRun(supplyanddemandareinelastic)QuantityofApartments0SupplyControlledrentRentalPriceofApartmentDemandShortage短期内，供给和需求都缺乏弹性较小短缺Figure3RentControlintheShortRunandintheLongRunCopyright©2003Southwestern/ThomsonLearning(b)RentControlintheLongRun(supplyanddemandareelastic)0RentalPriceofApartmentQuantityofApartmentsDemandSupplyControlledrentShortage长期内，供给和需求都富有弹性较大短缺Copyright©2004South-Western/ThomsonLearningHowPriceFloorsAffectMarketOutcomes价格下限如何影响市场结果•Whenthegovernmentimposesapricefloor,twooutcomesarepossible.•Thepricefloorisnotbindingifsetbelowtheequilibriumprice.•Thepricefloorisbindingifsetabovetheequilibriumprice,leadingtoasurplus.•有两种可能的结果：如果价格下限低于均衡价格，价格下限没有限制性；如果价格下限高于均衡价格，价格下限有限制性，会产生盈余。Figure4AMarketwithaPriceFloorCopyright©2003Southwestern/ThomsonLearning(a)APriceFloorThatIsNotBindingQuantityofIce-CreamCones0PriceofIce-CreamConeEquilibriumquantity2PricefloorEquilibriumpriceDemandSupply$3100Figure4AMarketwithaPriceFloorCopyright©2003Southwestern/ThomsonLearning(b)APriceFloorThatIsBindingQuantityofIce-CreamCones0PriceofIce-CreamConeDemandSupply$4Pricefloor80Quantitydemanded120QuantitysuppliedEquilibriumpriceSurplus3Copyright©2004South-Western/ThomsonLearningHowPriceFloorsAffectMarketOutcomes价格下限如何影响市场结果•Apricefloorpreventssupplyanddemandfrommovingtowardtheequilibriumpriceandquantity.•Whenth