經(jīng)濟(jì)學(xué)第五章

Supply,Demand,and

GovernmentPolicies6供給、需求與政府政策Inthischapter,

lookfortheanswerstothesequestions:Whatarepriceceilingsandpricefloors?

Whataresomeexamplesofeach?Howdopriceceilingsandpricefloorsaffectmarketoutcomes?Howdotaxesaffectmarketoutcomes?

Howdotheeffectsdependonwhether

thetaxisimposedonbuyersorsellers?Whatistheincidenceofatax?

Whatdeterminestheincidence?1什么是價(jià)格上限與價(jià)格下限？各有什么例子？?jī)r(jià)格上限與價(jià)格下限如何影響市場(chǎng)結(jié)果？

稅收如何影響市場(chǎng)結(jié)果？對(duì)買者還是賣者征稅對(duì)市場(chǎng)結(jié)果有什么不同嗎？什么是稅收歸宿？什么決定稅收歸宿？1SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESGovernmentPoliciesThatAlterthe

PrivateMarketOutcome

PricecontrolsPriceceiling:alegalmaximumontheprice

ofagoodorserviceExample:rentcontrol

Pricefloor:alegalminimumonthepriceof

agoodorserviceExample:minimumwage

TaxesThegovtcanmakebuyersorsellerspayaspecificamountoneachunitbought/sold.Wewillusethesupply/demandmodeltosee

howeachpolicyaffectsthemarketoutcome

(thepricebuyerspay,thepricesellersreceive,andeq’mquantity).價(jià)格控制：價(jià)格上限：出售一種物品或服務(wù)的法定最高價(jià)格比如：租金控制價(jià)格下限：出售一種物品或服務(wù)的法定最低價(jià)格

稅收：政府要求買者或賣者每買進(jìn)或賣出一單位物品所支付的一定數(shù)量的貨幣2SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESEXAMPLE1:TheMarketforApartmentsEq’mw/o

pricecontrolsPQDSRentalpriceofapts$800300Quantityofapartments沒(méi)有價(jià)格控制的均衡3SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESHowPriceCeilingsAffectMarketOutcomesApriceceiling

abovethe

eq’mpriceis

notbinding–

hasnoeffect

onthemarketoutcome.價(jià)格上限高于均衡均衡價(jià)格時(shí)沒(méi)有限制性—即對(duì)市場(chǎng)結(jié)果沒(méi)有影響

PQDS$800300Price

ceiling$10004SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESHowPriceCeilingsAffectMarketOutcomesTheeq’mprice($800)isabovetheceilingandthereforeillegal.違法的Theceiling

isabindingconstraint

ontheprice,causesashortage.PQDS$800Price

ceiling$500250400shortage5SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESHowPriceCeilingsAffectMarketOutcomesInthelongrun,supplyanddemand

aremore

price-elastic.So,theshortage

islarger.長(zhǎng)期，供給與需求都更具有彈性。因此，短期更加嚴(yán)重PQDS$800150Price

ceiling$500450shortage6SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESShortagesandRationing短缺與配給Withashortage,sellersmustrationthegoodsamongbuyers.Somerationingmechanisms:(1)Longlines

(2)Discriminationaccordingtosellers’biasesThesemechanismsareoftenunfair,andinefficient:thegoodsdonotnecessarilygotothebuyerswhovaluethemmosthighly.Incontrast,whenpricesarenotcontrolled,

therationingmechanismisefficient(thegoods

gotothebuyersthatvaluethemmosthighly)

andimpersonal(andthusfair).面臨短缺時(shí)，賣者必須在買者之間配給稀缺物品

配給機(jī)制：（1）排長(zhǎng)隊(duì)（2）根據(jù)賣者的偏好這些配件機(jī)制既可能是不公平的，也是無(wú)效率的：因?yàn)槲锲凡⒉灰欢〞?huì)賣給對(duì)它評(píng)價(jià)最高的買者與此相比，一個(gè)自由競(jìng)爭(zhēng)市場(chǎng)中的配給機(jī)制既有效率（物品賣給對(duì)它評(píng)價(jià)最高的買者），也是客觀的（就是公平的）7SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESEXAMPLE2:TheMarketforUnskilledLaborEq’mw/o

pricecontrolsWLDSWagepaidtounskilledworkers$4500Quantityofunskilledworkers8SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESHowPriceFloorsAffectMarketOutcomesWLDS$4500Price

floor$3Apricefloor

belowthe

eq’mpriceis

notbinding–

hasnoeffect

onthemarketoutcome.低于均衡價(jià)格的的價(jià)格下限沒(méi)有限制性—即對(duì)市場(chǎng)結(jié)果沒(méi)有影響9SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESHowPriceFloorsAffectMarketOutcomesWLDS$4Price

floor$5Theeq’mwage($4)isbelowthefloorandtherefore

illegal.Thefloor

isabindingconstraint

onthewage,

causesa

surplus(i.e.,unemployment).400550laborsurplus均衡價(jià)格（$4）低于價(jià)格下限，因此是違法的價(jià)格下限是一種限制性約束，引起了過(guò)剩（也就是失業(yè)10SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESMinwagelaws

donotaffect

highlyskilledworkers.Theydoaffectteenworkers.Studies:

A10%increase

intheminwageraisesteenunemployment

by1-3%.TheMinimumWageWLDS$4Min.wage$5400550unemp-loyment最低工資法對(duì)技能高的工人并沒(méi)有影響，它們影響的是青少年研究表明：最低工資每上升10%，就會(huì)使青少年就業(yè)減少1-3%。11SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESACTIVELEARNING1

PricecontrolsQPS0Themarketfor

hotelroomsDDetermine

effectsof:A.

$90price

ceilingB. $90price

floorC. $120price

floor1212SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESACTIVELEARNING1

A.$90priceceilingQPS0Themarketfor

hotelroomsDThepricefallsto$90.Buyersdemand

120rooms,sellerssupply90,leavingashortage.shortage=30Priceceiling1313SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESACTIVELEARNING1

B.$90pricefloorQPS0Themarketfor

hotelroomsDEq’mpriceisabovethefloor,sofloorisnotbinding.P=$100,

Q=100rooms.Pricefloor1414SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESACTIVELEARNING1

C.$120pricefloorQPS0Themarketfor

hotelroomsDTheprice

risesto$120.Buyers

demand

60rooms,

sellerssupply120,causingasurplus.surplus=60Pricefloor1515SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESEvaluatingPriceControlsRecalloneoftheTenPrinciplesfromChapter1:

Marketsareusuallyagoodway

toorganizeeconomicactivity.

Pricesarethesignalsthatguidetheallocationofsociety’sresources.Thisallocationisalteredwhenpolicymakersrestrictprices.Pricecontrolsoftenintendedtohelpthepoor,

butoftenhurtmorethanhelp.價(jià)格是指引社會(huì)資源配置的信號(hào)。當(dāng)政府進(jìn)行價(jià)格控制時(shí)，這種配置通常會(huì)發(fā)生變化價(jià)格控制想幫助窮人，但往往卻傷害了那些它本想幫助的人16SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESTaxesThegovtleviestaxesonmanygoods&servicestoraiserevenuetopayfornationaldefense,publicschools,etc.Thegovtcanmakebuyersorsellerspaythetax.Thetaxcanbea%ofthegood’sprice,

oraspecificamountforeachunitsold.Forsimplicity,weanalyzeper-unittaxesonly.政府對(duì)許多物品與勞務(wù)征稅是為了給國(guó)防，公立學(xué)校等這類公共項(xiàng)目籌資政府能想買者或賣者征稅稅收可以是物品價(jià)格的一個(gè)比例或者每售出一單位物品需支付一定數(shù)量的貨幣簡(jiǎn)化起見(jiàn)，我們僅分析后者17SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESS1EXAMPLE3:TheMarketforPizzaEq’m

w/otaxPQD1$10.0050018SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESS1D1$10.00500ATaxonBuyersThepricebuyerspay

isnow$1.50higherthanthemarketpriceP.Pwouldhavetofall

by$1.50tomake

buyerswilling

tobuysameQ

asbefore.E.g.,ifPfalls

from$10.00to$8.50,

buyersstillwillingto

purchase500pizzas.PQD2Effectsofa$1.50perunittaxonbuyers$8.50Hence,ataxonbuyersshiftstheDcurvedownbytheamountofthetax.Tax19SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESS1D1$10.00500ATaxonBuyersPQD2$11.00PB=$9.50PS=TaxEffectsofa$1.50perunittaxonbuyersNeweq’m:新均衡Q=450Sellers

receive

PS=$9.50Buyerspay

PB=$11.00Differencebetweenthem

=$1.50=tax45020SUPPLY,DEMAND,ANDGOVERNMENTPOLICIES450S1TheIncidenceofaTax:稅收歸宿howtheburdenofataxissharedamong

marketparticipants稅收負(fù)擔(dān)在市場(chǎng)參與者之間進(jìn)行分配的方式PQD1$10.00500D2$11.00PB=$9.50PS=TaxInourexample,buyerspay

$1.00more,sellersget

$0.50less.21SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESS1ATaxonSellersPQD1$10.00500S2Effectsofa$1.50perunittaxonsellersThetaxeffectivelyraisessellers’costsby

$1.50perpizza.Sellerswillsupply

500pizzas

onlyif

Prisesto$11.50,

tocompensatefor

thiscostincrease.$11.50Hence,ataxonsellersshiftsthe

Scurveupbytheamountofthetax.因此，對(duì)賣者征稅使供給曲線向上移動(dòng)，移動(dòng)幅度為稅收量Tax22SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESS1ATaxonSellersPQD1$10.00500S2450$11.00PB=$9.50PS=TaxEffectsofa$1.50perunittaxonsellersNeweq’m:Q=450Buyerspay

PB=$11.00Sellers

receive

PS=$9.50Differencebetweenthem

=$1.50=tax23SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESS1TheOutcomeIstheSameinBothCases!Whatmattersisthis:Ataxdrives

awedgebetweenthepricebuyerspayandthepricesellersreceive.PQD1$10.00500450$9.50$11.00PB=PS=TaxTheeffectsonPandQ,andthetaxincidencearethesamewhetherthetaxisimposedonbuyersorsellers!在這兩種情況下：稅收都在買者支付的價(jià)格和賣者得到的價(jià)格之間打入了一個(gè)契子24SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESACTIVELEARNING2

EffectsofataxQPS0Themarketfor

hotelroomsDSupposegovtimposesataxonbuyersof$30perroom.Findnew

Q,PB,PS,

andincidenceoftax.25SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESACTIVELEARNING2

AnswersQPS0Themarketfor

hotelroomsDQ=80PB=$110PS=$80Incidencebuyers:$10sellers:$20TaxPB=PS=26SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESElasticityandTaxIncidenceCASE1:SupplyismoreelasticthandemandPQDSTaxBuyers’shareoftaxburdenSellers’shareoftaxburdenPriceifnotaxPBPSIt’seasier

forsellersthanbuyerstoleavethemarket.Sobuyersbearmostoftheburden

ofthetax.27SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESElasticityandTaxIncidenceCASE2:DemandismoreelasticthansupplyPQDSTaxBuyers’shareoftaxburdenSellers’shareoftaxburdenPriceifnotaxPBPSIt’seasierforbuyersthansellerstoleavethemarket.Sellersbearmostoftheburdenof

thetax.28SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESCASESTUDY:WhoPaystheLuxuryTax?1990:Congressadoptedaluxurytaxonyachts,privateairplanes,furs,expensivecars,etc.Goalofthetax:raiserevenuefromthose

whocouldmosteasilyaffordtopay–

wealthyconsumers.Butwhoreallypaysthistax?在1990年，國(guó)會(huì)通過(guò)了一項(xiàng)針對(duì)游艇，私人飛機(jī)，皮衣，珠寶和豪華轎車這類物品的新的奢侈品稅稅收的目的；增加富人的稅收但真正支付稅收的人士誰(shuí)？29SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESCASESTUDY:WhoPaystheLuxuryTax?ThemarketforyachtsPQDSTaxBuyers’shareoftaxburdenSellers’shareoftaxburdenPBPSDemandis

price-elastic.Intheshortrun,supplyisinelastic.Hence,

companiesthatbuildyachtspaymostof

thetax.30SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESCONCLUSION:GovernmentPoliciesandtheAllocationofResources結(jié)論：政府政策與資源的配置Eachofthepoliciesinthischapteraffectstheallocationofsociety’sresources.Example1:Ataxonpizzareduceseq’mQ. Withlessproductionofpizza,resources(workers,ovens,cheese)willbecomeavailabletootherindustries.Example2:Abindingminimumwagecauses

asurplusofworkers,awasteofresources.So,it’simportantforpolicymakerstoapplysuchpoliciesverycarefully.本章的兩種政策都會(huì)影響社會(huì)資源的配置：

例1：對(duì)皮薩的征稅降低了均衡數(shù)量。當(dāng)皮薩的產(chǎn)量降低時(shí)，資源（工人，烤箱，奶酪）將會(huì)轉(zhuǎn)移到其它行業(yè)例2：一個(gè)限制性的最低工資會(huì)引起工人的超額供給，這是對(duì)資源的浪費(fèi)因此，決策者在應(yīng)用這些政策時(shí)需要非常小心31SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESCHAPTERSUMMARYApriceceil