城市经济学-class materials of micro-eco稀缺性选择和机会成本

城市经济学基本理论EconomicTheoriesand稀缺性，选择和机会Scarcity,choiceandopportunity稀缺性 Resources,noma-erhowlargetheymaybe,arelimited–thisisknownasItisthescarcitythatforcesharddecisionstobemadeaboutthealloca<onof自由物品（freegoods）：选择在有限的资howwedecidetoallocate,givenlimitedEconomicTheoriesand机机会成本OpportunityThisistherelevantcostofthedecisionbeingWheneverwechoosetohavemoreofonethingwemakesimultaneousdecisiontohavelessofsomethingItisthevalueofthenextbestalternativethatisgiven资A的机会成本，则该OCA=max(RB,RC,RD,式中：RBRCRD,……分别表示用于用途B,C,D城市经济学基本理论与概EconomicTheoriesand价价格调整区位平Pricesadjusttoachieveloca<onal城市经济学基本理论与概EconomicTheoriesand外部性外部性外部经济——外部性经济正效外部不经济——外部性经济负效在大多数交易中，消费者所支付的价格等于该商品的成benefits=然而，在某些情况下，参与交易以外的其他人将会承担部分成这就导致了外部成本的存当存在外部成本或收益时，我们并不认为市场均衡具有社会效城市经济学基本理论与概EconomicTheoriesand规规模Economiesof生产受规模经济的影Produc<onissubjecttoeconomiesof当生产的平均成本下降而产出上升时，便产生了规模经济规模经济产生的原因有两投入要素的不可分割性Indivisible一些资本投入存在粗放性，不能随生产规模的缩小而减较小的厂商投入同大厂商类似规模的生产要专业化因素Factor专业化工人的工作具有连续性和熟练性，提高了生产效率城市经济学基本理论与概EconomicTheoriesand比比较优势原理Principleofcompara<ve解释模布米布米每小时的6211机会成1/3kg3m1kg1m专业化导致生产的变120026321从交换中获取的收0+1+10城市经济学基本理论与概EconomicTheoriesand乘数Theoryofthe 卡恩（RFKahn）于乘数原理随其试用领域不同而有投资乘数，预算乘数，对外贸易数，货币创造乘数等例如投资乘数 的投资变动给国民收入总量带来的影响要比资变动本身大的多，投资的增加可能引起国民收入成倍的增城市经济学基本理论与概EconomicTheoriesand效用U<lity效用（utility):指消费者在消费过程中获得的一 心理满足X为某种物品或劳务，x为该种物品或劳务的消费量，则该种物或劳务的总效用函数为无差异Indifference需求和需求DemandandDemand需求量(Quan%tyDemanded)：消费者在某一给定价格下希 某种商品的数量需求（Demand）：在某一特定时期内，对应于某一商品的各种价格，人们 需求和需求DemandandDemand商品的需求函数（Demand 需求曲线（DemandCurve）一种商品的需求量和他的价格之间的函数关系的图像。需求规律（theLawofDemand）Lawofdemand‐whenthepriceofagoodrisesthentheamountofthatgoodthatisdemanded(quan%tydemanded)falls,converselywhenthepriceofagoodfalls,thentheamountofthatgooddemandedrises需求和需求DemandandDemand从个人需求到市场需求（FromindividualtomarketIndividualdemandcurvesrelate tyofagoodthatanconsumerwillpurchasetoits市场需求给定市场范围内所有消费者对Themarketdemandcurverelatesthe tyofagoodthatallconsumersinamarketwillbuytoitsprice.需求和需求DemandandDemandDemandandDemand需求函数的需求量和需求变化Shi=sindemandcurveversuschangesinquan%ty需求量的变在其他因素保持不变的情况下，商品自身价格的变化将引起需求量的变化是由内生变量的变化引起的。表现为在一条既定的需求曲线上点的位需求的变当商品自身价格不变，由于其它因素的变化引起的需求量的变是外生变量引起的，表现为整条需求曲线的移动需求和需求DemandandDemandAdecreaseinthepriceofagoodhastwo替代效应（substitutionThesubstitutioneffectoccursbecauseconsumerstendtobuymorethegoodthathas echeaperandlessofothergoodsthathavenowerelativelymoreexpensive. e eeffectoccursbecausesinceoneofthegoodsnowcheaper,consumershaveincreasedrealpurchasing Generally,substitutionand eeffectsoccursimultaneously.影响需求的消费者的偏影响需求的消费者的偏对未来的预DemandandDemand其它商品的Twogoodsareindependentifthechangeinthepriceofonegoodhasnoeffectonthequan<tydemandedoftheothergood.SupplyandSupplySupplySupplyandSupply供给供给——生产者在一定时期内在各种可能的价格下愿意且能够提供的商品的数供给量——生产者在某一价格下愿意而且能够（希望）出售的某种商品的数量个别供给——单个厂商对某种商品的供市场供给——在某个市场上所有提供相同商品的个别供给的总供给和供给SupplyandSupply一定时期内和一定市场中，某种商品的供给量和影响供给量的各个供给规律（Lawof供给和供给SupplyandSupply供给量供给量的变动(Shi=sinquan%tydemanded由商品自身价格的变化引起的供给量的变化，表现为在一条既定的供给供给的变动(Shi=sindemand当商品自身价格既定时，由于其他外生变量引起的供给量的变化，表现为影响供给的因 Equilibrium均衡Equilibrium均衡价格（Equilibrium均衡价格的变均衡Equilibrium均衡Equilibrium市场条件的变化可以导致下述四种情均衡Equilibrium均衡价消费者剩余（Consumer 生产者剩余（Producer社会生产的总剩余：消费者剩余加上生产者均衡Equilibrium最高限价总体上有利于消费者，带来社会总剩余的减少C——社会福利的无谓损失，降低社会资源的配消费者剩余的变 生产者剩余的变 ∆Cs=-费者剩余的变 ∆Cs=需求弹性Anelas-citymeasuresthesensi<vityofonevariabletoMorespecifically,itisthepercentagechangeinonevariableresul<ngfroma1percentincreaseinanother.需求需求弹性（Elas%cityofElas-cityofdemandrelatesthepercentagechangeinquan<tydemandedtothepercentagechangeinanothervariable(priceor 需求需需求的价格弹性（Priceelas%cityof方向的，需求的价格弹性一定是负数Thepriceelas-cityofdemandmeasuresthesensi<vityofquan<tydemandedpriceMorespecifically,itisthepercentagechangeinquan<tydemandedofaresul<ngfroma1percentincreaseinits

Ed=

弧弹 Ed=需求富有弹性EPD<- （priceConsump<onisrela<velysensi<vetopricechangesfora1percentdecreaseinpriceyouendupwithamorethan1percentincreaseinconsump<on EPD>- (priceinelas<cConsump<onisrela<velyinsensi<vetopricechangesfora1percentdecreaseinpriceyouendupwithlessthana1percentincreaseinconsump<on需求oConsump<onandpricemovepropor<onallytoeachother1:1toWhenthepriceelas-cityofdemandisconstantallalongthedemandcurve需求完全有弹性EPD（PerfectlyPriceDemandcurvewillbePricewillbePriceelas<cityisAnyamountwillbedemandedatagivenpricebutnonewillbedemandedabovethatprice EPD=0（PerfectlyPriceInelas<c）DemandcurvewillbeQuan<tywillbeConsumersdemandthesameamountregardlessoftheprice需求需求的价格弹性和需求曲需求的价格弹性等于P/Q与需求曲线斜率的倒数的Ed= 除了完全有弹性和完全无弹性，需求的价格弹性在斜率不变的曲线上是的对于任意一条线性需求曲线上的点来说，它在需求曲线上的位置越相应的点弹性数值就越大；相反，位置越低，相应的点弹性系数值越小需求影响需求价格弹性的因——需求需求的价格弹性的大小对商品生产者总收益的设某种商品的需求函数为Qd=f(P),厂商出售这种商品的总益TR=P*Qd=P*f(P),为 P的变化对TR的影响，对TR求P的一阶导 =Qd+P ]=Qd[1+Ed]需求的价格弹性的大小对消费者总支需求需求的收需求的收入弹性 eelas-cityofdemandmeasuresthesensi<vityofquan<tydemandedchanges Morespecifically,itisthepercentagechangeinquan<tydemandedofaresul<ngfroma1percentincrease 需求的收入弹性=需求量变化的百分比/收入变化的百分Ed’=𝑄↑′−𝑄/𝑄/𝑌↑′

EY= ∙ ·· 需求正正常品与次Normalvs.inferior正常品（NormalNormalgoodsarethosegoodsthatconsumerswanttopurchasemoreof Apples,notebooks,次等品（inferiorInferiorgoodsarethosegoodsthatconsumerswanttopurchaserela<velylessofeincreases(i.e.,comparedtoothergoods,theywanttoconsumelessofthegood e需求需求的收入弹EID0次等品（inferiorConsump<ondecreasesas eincreasesConsump<onincreases eEID=0 eConsump<onisconstant e0<EID< e（NormalIncreaseinconsump<onis ylessthanincreaseeEID=1unit（NormalEID> eLuxuryorsuperiorIncreaseinconsump<onispropor<ona ymorethanincreasein需求需求的交叉弹性（crosselas%cityofThecross-‐priceelas-cityofdemandisthepercentagechangeinthedemandedofonegoodresul<ngfroma1percentincreaseinthepriceof需求的交叉弹性=商品𝑋需求量变化的百分比/商品𝑌价格变化的百分Ed’’=𝑄𝑥↑′−𝑄𝑥/𝑄𝑥/𝑃𝑦↑′SupplySupplySupply供给弹性（Supply点弹性Es=𝑄𝑠↑′−𝑄𝑠/𝑄𝑠/𝑃↑′−𝑃/𝑃 =𝑃/𝑄𝑠 *∆𝑄/∆𝑃 弧弹Es𝑄𝑠↑𝑄𝑠/(𝑄𝑠+𝑄↑𝑠′)/2/𝑃↑′SupplySupplyEs=0完全无弹性（PerfectlyInelas<c）：当价格发生变动时，供给量全没有变化Es>1富有弹性（Elas<c）：量变化百分比大于价格变化百分Es=无穷，完全有弹性（PerfectlyElas<c）：价格任何微小的变化都以导致供给量无穷的变影响供给弹性因——生产的难易程——生产规模和规模变化的难易程——成本变需求，供给与市场Demand,Supplyand价格消费price-‐consump%onA54

D

需求曲线Demand4需求曲线Demand4EPriceE DemandGG

Food(unitsperDemand,Supplyand

收入消费收入消费D BA4 Food(unitsper4GEHGEDDD211 Food(unitsper基数效Cardinal U"lity,inaneconomiccontext,isanumericalscorewhichrepresentsthesa2sfac2onthataconsumerreceivesfromconsumingagivenmarketbasket.基数效用（Cardinal基数效用——是一种对效用的度量方法，指用基数1，2，3…….具体数量衡量效——可以具体计算并加总——边际效用分基数效Cardinal总效用，平均效用，和边际效总效用TUtotalu*lity——消费若干单位商品边边际效用MUmarginalu*lity——Cardinal总效用，平均效用，和边基数效CardinalLawofdiminishingmarginal边Lawofdiminishingmarginal加，从中得到的满足程度会逐渐下降Asmoreandmoreofagoodisconsumed,consump2onofaddi2onalunitsresultsinsmallerandsmalleraddi2onstou2lity.基数效Cardinal等边际效用Equalmarginal消费者多种商品的最大效用原则是：消费者花在每种物品上的单位货币支出的边际效用（这种商品的边际效用与其价格之比）彼此相等，都等于货币收Theequalmarginalprinciplestatesthatu*lity izedwhentheconsumerequalizedthemarginalu*lityperdollarofexpenditureacrossallgoodsMUx/PxMUy/Py λ边际效用序数效序数效用Ordinal序数效用假设偏好的完备性Preferencesareassumedtocomplete.Consumerscancompareandrankpossiblebasketsintheorderthey偏好的传递性,偏好的一致性MoreIsBetter：consumerswillalwaysprefermoreofanygoodtoConsumersareneverMoreisalwaysbetter,evenifitisjustalittlebit序数效Indifference无差异IndifferenceTheindifferencecurveillustratescombina2onsofmarketbasketsthatprovidetheconsumerwithanequivalentlevelofsa2sfac2on序数效Food

（替代商品）无差Indifference Clothing等效——x,y轴分别代表两种商品，效用面（totalu2litysurface）（constantu2litycurve），其特点——无差异曲线向右下方倾斜——无差异曲线的斜率是x,y两种商品的边际替代率(marginalrateof

IndifferencecurvesfromthesamemapcannotAccordingtothisdiagram,theconsumershouldbeindifferentamongbasketsA,BandA,D.YetBshouldbepreferredtoDbecauseBhasmoreofBOTHgoods.A Food序数效CocaCola(Cansper

互替商品的无Perfect Twogoodsareperfectsubs"tuteswhenthemarginalrateofsubs2tu2onofonefortheotherisconstant. Example:A wouldbewillingtogiveupthesameamountofCocaColatoconsumePepsi,regardlessof howmuchPepsitheyhavealreadyconsumed(Peoplenotdesireto“balance”theirconsump2onofsoda1

Pepsi(CansperLek

完全补足品PerfectTwogoodsareperfectcomplementswhenthemarginalrateofsubs2tu2oniseitherzeroorinfinite.Withperfectcomplements,addi2onalunitsofonegoodareofnovaluewithoutaddi2onalunitsoftheothergood.321

Right

序数效 中性商品无差异 肥皂序数效预算线（budget Budgetconstraintsarelimitsfacedbyconsumersbecauseof Abudgetconstraintisthesetofallbaskets(combina2onoftwoormorethatareaffordablewitha eandgiven方程I=PxX+PyY斜率T=Y/X=(I/PC)=40

BudgetThebudgetlinerepresentsthecombina*onsofgoodsthatcanbepurchasedgiventheconsumer’s eandthepricesofthegoods.LineAG(passesthroughpointsB,D,andE)showsthebudgetassociatedwithan eof$80,apriceoffoodofPF=$1/unitandapriceofclothingofPC=$2/unit.Theslopeofthebudgetline(betweenpointsBandD)is‐PF/PC=‐10/20=‐½.

BudgetlineF+2C=Slope∆C/∆F=‐½=DE

80=

Food**∆C/∆F=‐½measurestherela*vecostoffoodandclothingi.e.becauseclothingcosts$2/unitandfoodcosts$1/unit,½unitofclothingmustbegivenuptoget1unitoffood.

80

Effectsofchanges 4020

Achange e(withoutachangeinprices)thebudgetlinetoshiVparalleltotheoriginalbudgetline(L1).whenthe eof$80(L1)isincreasedto$160,thebudgetlineshiVsoutwardtoL2.If efallsto$40,thenthelineshiVsinwardtoL3.(I=(I=(I=

Food

商品价格变Effectsofchangesin

Achangeinthepriceofonegood(food),withoutachangein causesthebudgetlinetorotateabouttheinterceptofthegoodthatdidnotexperienceapricechange(clothing).InthisWhenthepriceoffoodfallsfrom$1to$0.50,thebudgetlineoutwardfromL1toL2(increaseinpurchasingOntheotherhand,whenthepriceoffoodincreasesfrom$1tothebudgetlinerotatesinwardfromL1toL3(decreaseinpurchasing (PF= (PF= (PF= Food序数效消费者均——序数效用理消费 MUx/PxMUy/Py λ=边际效用序数效收入扩展（消费）曲线 econsump*on e-‐consump"oncurverevealstheu2lity-‐ izingco ina2onsoftwogoodsasanindividualconsumer’s echanges. D BA 753

DBA44

Food(unitsper

收入消费Withallpricesofallgoodsfixed,increasesin ecauseconsumerstochangetheirchoicesofmarketInthetopgraph,thebasketsthatizeu2lityforvarious (pointA‐$10,pointB‐$20,andpointD‐$30)traceoutthe consump"oncurve.EE

HDGD2DG11

Thebouomgraphillustratestherightshikofthedemandcurveinresponsetoincreasesin (PointsE,G,andHcorrespondpointsA,B,andD, Food(unitsper

e-‐consump2on upwardbecausetheconsump2onofbothfoodandclothingincreaseas(units

e-consumption

eD B

illustra2onweobserved53Priceof

A44GEHGED2

Food(unitsper

alongasingledemandcurveresponsetochangesinthepriceofagood.Withthe curve,weobserveshiksinthedemandcurve.Sinceeachdemandcurveismeasuredforapar2cularlevelofe,anychangein emustleadtoashikinthedemandcurveTheupward-‐slo consump"oncurveimpliesthatanincreasein ecausesarightshikofthedemandcurve. Food(unitsper7

eIni2allythe eisTheu2lity-‐ eisatpointA.e-consumption eincreasesto$203D observeanoutwardshikinthe3B line,allowingtheconsumerto theu2litylevelassociatedwith indifferencecurveU2.The izingchoiceisnowatpointPriceof

GE4HGE4D2

Food(unitsper

eincreasesyetagain$30weobserveanotheroutwardshikinthebudgetline,allowingtheconsumertoauaintheu2litylevelassociatedwiththeindifferencecurveU3.Theu2lity izingchoiceisnowatpointD. Food(unitsper序数效价格消费曲线（priceconsump*on izingcombina2onsofgoodsasthepriceofoneofthosegoods商品价格变化——预算线变化——价格消费曲线数学方程 I=序数效

Price

Ini2allythepriceoffoodis$1andu2lity izedatpointBwhichisassociatedwiththeindifferencecurve 5444EPriceE

D

Food(unitsper

Whenthepriceoffoodincreasestothebudgetlinerotatesinwardesmoresteep–thehigherrela2vepriceoffoodcausedtheincreaseintheslopeofthebudgetline.umu2lityisnowauainedatpointAwhichisassociatedwiththeindifferencecurveU1.Theincreasedpriceoffoodhasdecreasedtheconsumer’spurchasingpowerandin

GGH

ngsohasalsodecreasedWhenthepriceoffooddecreases,thebudgetlinerotateoutwardandtheconsumermovestoindifferencecurveU3.Ahigherlevelofu2lityisnowachievedatpointD.

Food(unitspercurveandtheindividualdemand 54

D

价价格消费price-‐consump*on需求曲Demand4 Food需求曲Demand4EPriceE DemandGG

Food(unitsper序数效收入效应和替代效 分 力增加而增购这种商品（收入效应）在价格下降的过程中，这两种效应是同时发生的（Generally,subs2tu2oneeffectsoccursimultaneously.）当一种商品的价格下降时，发生两种效应（Adecreaseinthepriceofagoodtwo替代效应——效用水平保持不变时，由于商品价格的变化导致对该商品消费pauernofincreasingconsump2oninresponsetoadecreaseinpricealmostalways 价格变化的总效应——替代效应+收入效正常物劣等吉芬吉芬DosuchgoodsevenAnewstudybyRobertJensenandNolanMiller,economistsatKennedySchool,answerthis哈佛经城市经济学基本理论EconomicTheoriesand稀缺性，选择和机会Scarcity,choiceandopportunity稀缺性 Resources,noma-erhowlargetheymaybe,arelimited–thisisknownasItisthescarcitythatforcesharddecisionstobemadeaboutthealloca<onof自由物品（freegoods）：选择在有限的资howwedecidetoallocate,givenlimitedEconomicTheoriesand机机会成本OpportunityThisistherelevantcostofthedecisionbeingWheneverwechoosetohavemoreofonethingwemakesimultaneousdecisiontohavelessofsomethingItisthevalueofthenextbestalternativethatisgiven资A的机会成本，则该OCA=max(RB,RC,RD,式中：RBRCRD,……分别表示用于用途B,C,D城市经济城市经济学基本理论EconomicTheoriesand外部性外部性外部经济——外部性经济正效外部不经济——外部性经济负效在大多数交易中，消费者所支付的价格等于该商品的成benefits=然而，在某些情况下，参与交易以外的其他人将会承担部分成这就导致了外部成本的存当存在外部成本或收益时，我们并不认为市场均衡具有社会效城市经济学基本理论与概EconomicTheoriesand效用U9lity效用（utility):指消费者在消费过程中获得的一 心理满足X为某种物品或劳务，x为该种物品或劳务的消费量，则该种物或劳务的总效用函数为无差异Indifference城市经济城市经济学基本理论EconomicTheoriesand消费者在消费若干数量的某种物品或劳务时，每一新增单品或劳务所带来的总效用的变MUx=∆TUx/边际效用递减规(Lawofdiminishingmarginal在技术不变和其它生产因素不变的前提下，连续地把同一单位的可投入量增加到一定数量的其它投入量上所引起的增量是递减的趋势物品价格：物品或劳务的稀缺性，即边际效用思考：水和钻Thetheoryofthedecisionsandhowitscostsvarywithitsoutput.Knowledgeofproduc9onandcostshelpstobuildanunderstandingofcharacteris9csofmarket成成生产会计Accoun<ngAccoun<ngcostsareactualexpenses,includinghistoricalcosts,pluschargesforcapital生产经济成本（economicEconomiccostsarethecoststoafirmofu<lizingeconomicresourcesinincludingopportunity——显性成本（explicit——隐性成本（implicit生产短期成本和长期成总成本，平均成本和边际总成本（TC）——生产某一特定数量产品所付出的成本总额TCFCTotalcostisthetotaleconomiccostofconsis<ngoffixedandvariable变动成本variablecost(VC)——随着产量变化而变化的成本平均成本（AC）——AC=𝑇𝐶/𝑄𝑇𝐹𝐶/𝑄𝑇𝑉𝐶/𝑄(平均固定成本+平均变动成本化∆Q=生产沉没成本和沉没成本SunkCosts——SunkcostsareexpendituresthathavebeenmadeandcannotbeCostCostCost短期成本平均固定成本曲线平均变动成本曲线平均成本曲线边际成本曲成本函Cost长期平均成本（envelopcurve）长期总成本曲TheEquilibriumofthe厂商均TheEquilibriumofthe总产量，平均化厂商均TheEquilibriumofthe等产量曲线Anisoquantisashowingallpossiblecombina<onsofinputsthatyieldthesameoutput.厂商均TheEquilibriumofthe等成本 厂商均TheEquilibriumofthe厂商厂商均TheEquilibriumofthe利润最 利润最 ——平均收益——边际收益利润最 边际收益递减规律thelawofdiminishing在其他生产要素保持不变的条件下，如果连续的增加某种生产要素的量，那么到达某一点以后，总产量的增量是递减TheLawofdiminishingmarginalreturnsis