消費(fèi)者的需求www

ConsumerDemand

消費(fèi)者的需求

PatternsofConsumption70%ofhouseholdbudgetsisspentonhousing,transportationandfood.“Essential”itemshavechangedfromyearsago.消費(fèi)的類(lèi)型

住宅、交通費(fèi)用、食品支出，三者占百分之七十，大部分的人都認(rèn)為這些支出，係支用於必需品上

HowtheConsumerDollar

IsSpentHousing(shelter,furnishings,upkeep)36.4Transportation21.3Food14.9Clothing4.9Medicalcare6.1Othergoodsandservices11.0Entertainment5.4DeterminantsofDemandWhatdetermineswhatwebuy?需求決定的因子

嗜好（對(duì)這個(gè)財(cái)貨以及其他財(cái)貨慾望）所得（消費(fèi)者的所得）預(yù)期（對(duì)所得﹑價(jià)格及嗜好預(yù)期）其他財(cái)貨（其他財(cái)貨的存在以及其價(jià)格）在市場(chǎng)上消費(fèi)者人數(shù)多寡TheSociopsychiatricExplanationThedesireforgoodsandservicesarisesfromourneedsforsocialacceptance,security,andegogratification.TheSociopsychiatricExplanation“KeepingupwiththeJoneses”SelfpreservationExpressionsofaffluenceAffluentTeenagers0102030405060708090100PercentofTeensOwningItemTelevision84%Stereo81%Computer77%Videogamesystem64%CDburner49%Cellphone47%In-lineskates34%DigitalCamera27%Auto37%DVDplayer61%Pager/beeper9%TheEconomicExplanationDemand–Theabilityandwillingnesstobuyspecificquantitiesofagoodatalternativepricesinagiventimeperiod,ceterisparibus.經(jīng)濟(jì)學(xué)家強(qiáng)調(diào)，我們說(shuō)某一個(gè)人對(duì)財(cái)貨有需求，是指那個(gè)人一定要有能力以及意願(yuàn)，在那個(gè)價(jià)格水準(zhǔn)之下來(lái)購(gòu)買(mǎi)。DeterminantsofMarketDemandTastes—desireforthisandothergoods嗜好（對(duì)這個(gè)財(cái)貨以及其他財(cái)貨慾望）Ifastudysaysicecreamisgoodforyou,thedemandforicecreamwouldincrease.DeterminantsofMarketDemandIncome(oftheconsumer)所得（消費(fèi)者的所得）Ifyouwonthelotteryyoumightbuymoreicecream.Thedemandforicecreamwouldincrease,shiftingthedemandcurvetotheright.DeterminantsofMarketDemandExpectations(forincome,prices,tastes)預(yù)期（對(duì)所得﹑價(jià)格及嗜好預(yù)期）Ifyouknewyouweregoingtogetrichsoonyoumightdepletesavingstobuymoreicecreamnow.Increasesthedemandforicecream.DeterminantsofMarketDemandOthergoods(theiravailabilityandprices)其他財(cái)貨（其他財(cái)貨的存在以及其價(jià)格）Ifthepriceofchocolatecandybarsincreased,youmightbuyicecreaminsteadofacandybar.Increasesthedemandforicecream.DeterminantsofMarketDemandThenumberofconsumersinthemarket.在市場(chǎng)上消費(fèi)者人數(shù)多寡Ifthenumberofbuyersintheicecreammarketincreased,thedemandforicecreamwouldalsoincrease.MarketDemandThetotalquantitiesofagoodorservicepeoplearewillingandabletobuyatalternativepricesinagiventimeperiod.Marketdemandisthesumofindividualdemands.UtilityTheory（效用理論）Economistsassumethatthemorepleasureaproductgives,thehigherpricebuyersarewillingtopay.如果這個(gè)產(chǎn)品給我們更多的快樂(lè)，我們會(huì)對(duì)這些產(chǎn)品所支付的錢(qián)越高。例如在看電影前，有一包爆米花，能夠真正給你，討你喜歡，那你會(huì)真的有意願(yuàn)購(gòu)買(mǎi)。UtilityTheoryStudentswholikebutterarewillingtopaymoreforbutteredpopcornthannon-butteredpopcornbecauseitoffersmoretotalutility.Totalvs.MarginalUtilityUtilityisthepleasureorsatisfactionobtainedfromgoodorservice.從財(cái)貨或勞務(wù)中獲得的滿足或喜樂(lè)Totalutilityistheamountofsatisfactionobtainedfromentireconsumptionofaproduct.總效用則是指全部消費(fèi)這項(xiàng)產(chǎn)品帶給你消費(fèi)的滿足

Totalvs.MarginalUtilityMarginalutilityisthechangeintotalutilityobtainedbyconsumingoneadditional(marginal)unitofagoodorservice.邊際效用是指針對(duì)某一個(gè)財(cái)貨，消費(fèi)最後一個(gè)單位所帶來(lái)給你的滿足。Totalvs.MarginalUtilityMarginalutilityisthechangeintotalutilityobtainedbyconsumingoneadditional(marginal)unitofagoodorservice.LawofDiminishingMarginalUtilityThemarginalutilityofagooddeclinesasmoreofitisconsumedinagiventimeperiod.在一定的時(shí)間內(nèi)，乙個(gè)產(chǎn)品的邊際效用會(huì)隨著消費(fèi)量的增加而減少。我們假定每張嘴巴所吃的東西會(huì)產(chǎn)生興趣遞減，例如第一包爆米花，會(huì)帶來(lái)感覺(jué)上的滿足，但是第二包跟第三包吃下去後，有可能帶給你不舒服的感覺(jué)，

LawofDiminishingMarginalUtilityAstudentwhoenjoyspopcorncaneatallhewantsforfree.Thefirstboxconsumedisrewarding.Thesecondboxgood.Athirdboxdecent,etc.Aftereatingasixthbox,hegetssick.LawofDiminishingMarginalUtilityDidthesixthboxincreasehissatisfaction?No,ithadanegativemarginalutility.LawofDiminishingMarginalUtilityAslongasthemarginalutilityispositive,theconsumerreceivesadditionalsatisfactionandtotalutilityincreases.LawofDiminishingMarginalUtilityAdditionalquantitiesofagoodyieldincreasinglysmallerincrementsofsatisfaction.DeclineintotalutilityNegativemarginalutilityRisingtotalutility1023465QUANTITYOFPOPCORNTOTALUTILITY(utilitypershow)TotalutilityDiminishingmarginalutility5Marginalutility102346QUANTITYOFPOPCORNMARGINALUTILITY(utilityperbox)Totalvs.MarginalUtilityUtilityTheory

效用理論

Anabsolutemeasureofutilityisnotpossiblebecausetheperceptionofsatisfactiondiffersamongindividuals.效用沒(méi)有絕對(duì)衡量的標(biāo)準(zhǔn),這是因?yàn)槊恳粋€(gè)人的標(biāo)準(zhǔn)不一。UtilityTheoryDiminishingmarginalutilityisacommonexperience.Itisasufficientbasisforeconomicpredictionsofconsumerbehavior.UtilityTheoryWhydowewastewatereventhoughitisvitaltohumanlife?Weconsumesomuchwaterthatadditionalwaterofferslittle(ifany)marginalutility.水的邊際效用比較少PriceandQuantity

價(jià)格與數(shù)量

Manyforcesdeterminehowmuchwearewillingtobuy.PriceandQuantityEconomistsfocusontherelationshipbetweenpriceandquantityratherthantryingtoexplainalltheforcesatonce.Thisistheceterisparibusassumption.LawofDemandTheconceptsofmarginalutilityandceterisparibusexplainthedownwardslopeofthedemandcurve.

邊際效用以及其他不變的假設(shè)下,用以解釋需求曲線係向右下方延伸的曲線LawofDemandWithgivenincome,taste,expectations,andpricesofothergoodsandservices,peoplearewillingtobuyadditionalquantitiesofagoodonlyifitspricefalls.在所得、嗜好、預(yù)期、其他財(cái)貨不變的假設(shè)下，如果價(jià)格下跌，消費(fèi)者會(huì)增加購(gòu)買(mǎi)數(shù)量。LawofDemandThehigherthemarginalutility,themoreyouarewillingtopay.邊際效用愈高，吾人支付較多LawofDemandDiminishingmarginalutilityexplainswhypricemustdecreaseinorderforyoutocontinuetobuyagoodorservice.LawofDemandAccordingtothelawofdemand,thequantityofagooddemandedinagiventimeperiodincreasesasitspricefalls,ceterisparibus.DemandScheduleDemandCurveThequantitiesofagoodaconsumeriswillingandabletobuyatalternativepricesinagiventimeperiod,ceterisparibus.246810121416182022242628303200.050.100.150.200.250.300.350.400.450.50$0.55AQUANTITYDEMANDED(ouncespershow)PRICE(perounce)BCDGFHIJEAsmarginalutilitydeclines,sodoesthewillingnesstopayDemandCurvePriceElasticity

價(jià)格彈性

Theresponseofconsumerstoachangeinpriceismeasuredbythepriceelasticityofdemand.需要價(jià)格彈性是指需要的數(shù)量變化的百分比，比上價(jià)格變化百分比

PriceElasticityThepriceelasticityofdemandisthepercentagechangeinquantitydemandeddividedbythepercentagechangeinprice.PriceElasticityThepriceofpopcorngoesup20%andthequantitydemandedgoesdown10%.(E)=percentagechangeinquantitydemandedpercentagechangeinprice=–10%20%–0.5=Theelasticityis:Elasticvs.InelasticDemandDemandcanbeelastic,inelastic,orunitaryelastic.有彈性的沒(méi)彈性的，以及單一彈性。

ElasticDemandDemandiselasticiftheabsolutevalueofEisgreaterthan1.Consumerresponseislargerelativetochangeinprice.如果價(jià)格彈性大於一，我們說(shuō)需求是有彈性的，消費(fèi)者對(duì)購(gòu)買(mǎi)量的變動(dòng)大於價(jià)格的變動(dòng)InelasticDemandDemandisinelasticiftheabsolutevalueofEislessthan1.如果需要價(jià)格彈性少於一，我們說(shuō)需求是沒(méi)有彈性的，例如前面研究爆米花彈性是0.5

Consumersarenotveryresponsivetopricechanges.UnitaryElasticDemandDemandisunitaryelasticiftheabsolutevalueofEequals1.Thepercentagechangeinquantitydemandedisequaltothepercentagechangeinprice.如果價(jià)格彈性等於一，我們稱(chēng)需求為單一彈性，在這例子裡面，需要數(shù)量變化百分比，比價(jià)格變化百分比完全相同，需要變化數(shù)量百分比價(jià)格數(shù)量相同。

ElasticityEstimatesElasticityEstimatesProductsthathaveelasticdemandsareairlinetravel,freshfishandnewcars.Productsthathaveinelasticdemandarecigarettes,gasolineandcoffee.PriceElasticityandTotalRevenue

價(jià)格彈性及總收益

Priceelasticityexplainswhyproducerscannotchargethehighestpossibleprice.Higherpricesmayactuallylowertotalsalesrevenue.生產(chǎn)者以較高的價(jià)格來(lái)定價(jià)的這種觀念是不對(duì)的

PriceElasticityandTotalRevenueTotalrevenue

—thepriceofaproductmultipliedbythequantitysoldinagiventimeperiod.Totalrevenue=priceXquantitysold總收益

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價(jià)格

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賣(mài)出去數(shù)量

ElasticityandTotalRevenue246810121416182022242628303200.050.100.150.200.250.300.350.400.450.50$0.55QUANTITYDEMANDED(ouncespershow)PRICE(perounce)GElasticityandTotalRevenuePricecutsincreasetotalrevenueifE>1.FTotalrevenue=$3.00Totalrevenue=$3.20Totalrevenue=$3.00HPricecutsdecreasetotalrevenueifE<1.ElasticityandTotalRevenuePricecutsreducetotalrevenueifdemandispriceinelastic.Pricecutsincreasetotalrevenueifdemandispriceelastic.Pricecutsdonotchangetotalrevenueifdemandisunitaryelastic.DeterminantsofElasticity

彈性決定因素

Differencesinpriceelasticityareexplainedbyseveralfactors:Necessitiesvs.luxuries（必需品及奢侈品）

Availabilityofsubstitutes（代替品的程度）

Relativeprice（價(jià)格相對(duì)所得的影響）

Necessitiesvs.LuxuriesSomegoodsaresocriticaltooureverydaylifethatweregardthemasnecessities