供給、需求與政府政策

供給、需求與政府政策供給、需求與政府政策供給、需求與政府政策

在一個(gè)沒(méi)有政府管制的競(jìng)爭(zhēng)市場(chǎng)上，市場(chǎng)力量調(diào)整均衡價(jià)格、均衡數(shù)量.并非每個(gè)人對(duì)這種自由市場(chǎng)調(diào)整過(guò)程的結(jié)果都感到滿(mǎn)意.經(jīng)濟(jì)學(xué)家的作用之一便是運(yùn)用他們的理論幫助世界更好.價(jià)格控制政策制定者認(rèn)為一種物品或勞務(wù)的市場(chǎng)價(jià)格對(duì)買(mǎi)者或賣(mài)者不公平時(shí)所實(shí)施的.政府定出的價(jià)格上限和價(jià)格下限.價(jià)格控制價(jià)格上限（PriceCeiling）可以出售一種物品的法定最高價(jià)格. 價(jià)格下限（PriceFloor）可以出售一種物品的法定最低價(jià)格. 價(jià)格上限如何影響市場(chǎng)結(jié)果政府實(shí)現(xiàn)價(jià)格上限時(shí)可能有兩種結(jié)果:價(jià)格上限高于均衡價(jià)格，價(jià)格上限沒(méi)有限制作用.價(jià)格上限低于于均衡價(jià)格，價(jià)格上限有限制性約束.Figure1AMarketwithaPriceCeiling(a)APriceCeilingThatIsNotBindingQuantityofIce-CreamCones0PriceofIce-CreamConeEquilibriumquantity$4PriceceilingEquilibriumpriceDemandSupply3100Figure1AMarketwithaPriceCeilingCopyright?2003Southwestern/ThomsonLearning(b)APriceCeilingThatIsBindingQuantityofIce-CreamCones0PriceofIce-CreamConeDemandSupply2PriceceilingShortage75Quantitysupplied125QuantitydemandedEquilibriumprice$3價(jià)格上限如何影響市場(chǎng)結(jié)果價(jià)格上限的結(jié)果有限制作用的價(jià)格上限導(dǎo)致QD>QS，帶來(lái)短缺.比如：計(jì)劃經(jīng)濟(jì)的各種票證

非價(jià)格配給機(jī)制 比如:排長(zhǎng)隊(duì)，賣(mài)者歧視第一，經(jīng)濟(jì)學(xué)家?guī)缀跻恢抡J(rèn)為對(duì)市場(chǎng)干預(yù)具有某種必要性。第二，經(jīng)濟(jì)學(xué)家認(rèn)為應(yīng)當(dāng)注意對(duì)供求規(guī)律作用干預(yù)不同方式選擇。區(qū)分兩類(lèi)干預(yù)方式：一種是取消市場(chǎng)機(jī)制的干預(yù)方式另一種是與供求規(guī)律具有兼容性的干預(yù)方式1973,OPEC提高了世界石油市場(chǎng)的原油價(jià)格.由于原油是用于生產(chǎn)汽油的主要投入,較高的石油價(jià)格減少了汽油供給.什么導(dǎo)致了人們排隊(duì)加油呢?案例:加油站前的長(zhǎng)隊(duì)經(jīng)濟(jì)學(xué)家認(rèn)為政府的價(jià)格管制要為美國(guó)人排隊(duì)等候買(mǎi)汽油而失去的許多時(shí)間承擔(dān)部分責(zé)任.Figure2TheMarketforGasolinewithaPriceCeilingCopyright?2003Southwestern/ThomsonLearning(a)ThePriceCeilingonGasolineIsNotBindingQuantityofGasoline0PriceofGasoline1.Initially,thepriceceilingisnotbinding...PriceceilingDemandSupply,S1P1Q1Figure2TheMarketforGasolinewithaPriceCeilingCopyright?2003Southwestern/ThomsonLearning(b)ThePriceCeilingonGasolineIsBindingQuantityofGasoline0PriceofGasolineDemandS1S2PriceceilingQS4....resultinginashortage.3....thepriceceilingbecomesbinding...2....butwhensupplyfalls...P2QDP1Q1案例研究:

短期與長(zhǎng)期租金控制租金控制是地方政府規(guī)定房東向房東收取的租金上限該政策的目的是幫助窮人更能租得起住房.一位經(jīng)濟(jì)學(xué)家稱(chēng)租金控制是“除了轟炸之外，毀滅一個(gè)城市的最好方法.”Figure3RentControlintheShortRunandintheLongRunCopyright?2003Southwestern/ThomsonLearning(a)RentControlintheShortRun(supplyanddemandareinelastic)QuantityofApartments0SupplyControlledrentRentalPriceofApartmentDemandShortageFigure3RentControlintheShortRunandintheLongRunCopyright?2003Southwestern/ThomsonLearning(b)RentControlintheLongRun(supplyanddemandareelastic)0RentalPriceofApartmentQuantityofApartmentsDemandSupplyControlledrentShortage價(jià)格下限如何影響市場(chǎng)結(jié)果政府實(shí)行價(jià)格下限時(shí)，可能有兩種結(jié)果.均衡價(jià)格高于價(jià)格下限，價(jià)格下限沒(méi)有限制性.均衡價(jià)格低于價(jià)格下限，價(jià)格下限有限制性，引起過(guò)剩.Figure4AMarketwithaPriceFloorCopyright?2003Southwestern/ThomsonLearning(a)APriceFloorThatIsNotBindingQuantityofIce-CreamCones0PriceofIce-CreamConeEquilibriumquantity2PricefloorEquilibriumpriceDemandSupply$3100Figure4AMarketwithaPriceFloorCopyright?2003Southwestern/ThomsonLearning(b)APriceFloorThatIsBindingQuantityofIce-CreamCones0PriceofIce-CreamConeDemandSupply$4Pricefloor80Quantitydemanded120QuantitysuppliedEquilibriumpriceSurplus3價(jià)格下限如何影響市場(chǎng)結(jié)果價(jià)格下限阻止供求力量使價(jià)格向均衡價(jià)格變動(dòng).當(dāng)市場(chǎng)價(jià)格達(dá)到下限時(shí)，就不能再下降了，此時(shí)的市場(chǎng)價(jià)格等于價(jià)格下限.價(jià)格下限如何影響市場(chǎng)結(jié)果有限制性的價(jià)格下限會(huì)導(dǎo)致...QS>QD，引起過(guò)剩.非價(jià)格機(jī)制用歧視標(biāo)準(zhǔn)等代替價(jià)格機(jī)制作為配給機(jī)制.比如:最低工作，農(nóng)業(yè)價(jià)格支持 最低工資價(jià)格下限的一個(gè)重要例子是最低工資。最低工資法規(guī)定了任何一個(gè)雇主要支付的最低勞動(dòng)力價(jià)格。Figure5HowtheMinimumWageAffectstheLaborMarketCopyright?2003Southwestern/ThomsonLearningQuantityofLaborWage0LabordemandLaborSupplyEquilibriumemploymentEquilibriumwageFigure5HowtheMinimumWageAffectstheLaborMarketCopyright?2003Southwestern/ThomsonLearningQuantityofLaborWage0LaborSupplyLaborsurplus(unemployment)LabordemandMinimumwageQuantitydemandedQuantitysupplied稅收政府用稅收為公共項(xiàng)目籌資.稅收歸宿稅收歸宿（Taxincidence）：如何在市場(chǎng)參與者間分擔(dān)稅收負(fù)擔(dān)Figure6ATaxonBuyersCopyright?2003Southwestern/ThomsonLearningQuantityofIce-CreamCones0PriceofIce-CreamConePricewithouttaxPricesellersreceiveEquilibriumwithouttaxTax($0.50)PricebuyerspayD1D2Supply,S1Ataxonbuyersshiftsthedemandcurvedownwardbythesizeofthetax($0.50).$3.3090Equilibriumwithtax2.803.00100向買(mǎi)者（和賣(mài)者）征稅如何影響市場(chǎng)結(jié)果稅收抑制了市場(chǎng)活動(dòng).當(dāng)對(duì)一種物品征稅時(shí)，該物品在新均衡時(shí)的銷(xiāo)售量減少了.買(mǎi)者與賣(mài)者分?jǐn)偠愂肇?fù)擔(dān).Figure7ATaxonSellersCopyright?2003Southwestern/ThomsonLearning2.80QuantityofIce-CreamCones0PriceofIce-CreamConePricewithouttaxPricesellersreceiveEquilibriumwithtaxEquilibriumwithouttaxTax($0.50)PricebuyerspayS1S2Demand,D1Ataxonsellersshiftsthesupplycurveupwardbytheamountofthetax($0.50).3.00100$3.3090對(duì)買(mǎi)者征稅和賣(mài)者征稅是相同的Figure8工薪稅Copyright?2003Southwestern/ThomsonLearningQuantityofLabor0Wage

LabordemandLaborsupply稅收楔子WageworkersreceiveWagefirmspayWagewithouttax彈性與稅收歸宿稅收歸宿是關(guān)于誰(shuí)來(lái)承擔(dān)稅收負(fù)擔(dān)的研究.稅收導(dǎo)致市場(chǎng)均衡的變化.無(wú)論對(duì)誰(shuí)征稅，買(mǎi)者與賣(mài)者分?jǐn)偠愂肇?fù)擔(dān).彈性與稅收歸宿稅收負(fù)擔(dān)如何劃分?答案取決于需求和供給的相對(duì)彈性.Figure9HowtheBurdenofaTaxIsDividedCopyright?2003Southwestern/ThomsonLearningQuantity0PriceDemandSupplyTaxPricesellersreceivePricebuyerspay(a)ElasticSupply,InelasticDemand2....theincidenceofthetaxfallsmoreheavilyonconsumers...1.Whensupplyismoreelasticthandemand...Pricewithouttax3....thanonproducers.Figure9HowtheBurdenofaTaxIsDividedCopyright?2003Southwestern/ThomsonLearningQuantity0PriceDemandSupplyTaxPricesellersreceivePricebuyerspay(b)InelasticSupply,ElasticDemand3....thanonconsumers.1.Whendemandismoreelasticthansupply...Pricewithouttax2....theincidenceofthetaxfallsmoreheavilyonproducers... 稅收負(fù)擔(dān)如何劃分?稅收負(fù)擔(dān)更多地落在缺乏彈性的市場(chǎng)一方身上.ELASTICITYANDTAXINCIDENCESummaryPricecontrolsincludepriceceilingsandpricefloors.Apriceceilingisalegalmaximumonthepriceofagoodorservice.Anexleisrentcontrol.Apricefloorisa