經(jīng)濟學第五章

Supply,Demand,and

GovernmentPolicies6供給、需求與政府政策Inthischapter,

lookfortheanswerstothesequestions:Whatarepriceceilingsandpricefloors?

Whataresomeexamplesofeach?Howdopriceceilingsandpricefloorsaffectmarketoutcomes?Howdotaxesaffectmarketoutcomes?

Howdotheeffectsdependonwhether

thetaxisimposedonbuyersorsellers?Whatistheincidenceofatax?

Whatdeterminestheincidence?1什么是價格上限與價格下限？各有什么例子？價格上限與價格下限如何影響市場結(jié)果？

稅收如何影響市場結(jié)果？對買者還是賣者征稅對市場結(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).價格控制：價格上限：出售一種物品或服務的法定最高價格比如：租金控制價格下限：出售一種物品或服務的法定最低價格

稅收：政府要求買者或賣者每買進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沒有價格控制的均衡3SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESHowPriceCeilingsAffectMarketOutcomesApriceceiling

abovethe

eq’mpriceis

notbinding–

hasnoeffect

onthemarketoutcome.價格上限高于均衡均衡價格時沒有限制性—即對市場結(jié)果沒有影響

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.長期，供給與需求都更具有彈性。因此，短期更加嚴重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，賣者必須在買者之間配給稀缺物品

配給機制：（1）排長隊（2）根據(jù)賣者的偏好這些配件機制既可能是不公平的，也是無效率的：因為物品并不一定會賣給對它評價最高的買者與此相比，一個自由競爭市場中的配給機制既有效率（物品賣給對它評價最高的買者），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.低于均衡價格的的價格下限沒有限制性—即對市場結(jié)果沒有影響9SUPPLY,DEMAND,ANDGOVERNMENTPOLICIESHowPriceFloorsAffectMarketOutcomesWLDS$4Price

floor$5Theeq’mwage($4)isbelowthefloorandtherefore

illegal.Thefloor

isabindingconstraint

onthewage,

causesa

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

donotaffect

highlyskilledworkers.Theydoaffectteenworkers.Studies:

A10%increase

intheminwageraisesteenunemployment

by1-3%.TheMinimumWageWLDS$4Min.wage$5400550unemp-loyment最低工資法對技能高的工人并沒有影響，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.價格是指引社會資源配置的信號。當政府進行價格控制時，這種配置通常會發(fā)生變化價格控制想幫助窮人，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.政府對許多物品與勞務征稅是為了給國防，公立學校等這類公共項目籌資政府能想買者或賣者征稅稅收可以是物品價格的一個比例或者每售出一單位物品需支付一定數(shù)量的貨幣簡化起見，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稅收負擔在市場參與者之間進行分配的方式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，對賣者征稅使供給曲線向上移動，移動幅度為稅收量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格和賣者得到的價格之間打入了一個契子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，國會通過了一項針對游艇，私人飛機，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？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影響社會資源的配置：

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