Chap-04-The-Market-Forces-of-Supply-and-Demand市场供求力量

,TheMarketForcesofSupplyandDemand,Chapter4,TheMarketForcesofSupplyandDemand（供给与需求）,Supplyanddemandarethetwowordsthateconomistsusemostoften.Supplyanddemandaretheforcesthatmakemarketeconomieswork.Modernmicroeconemicsisaboutsupply,demand,andmarketequilibrium（市场均衡）.,Markets,Amarketisagroupofbuyersandsellersofaparticulargoodorservice.Thetermssupplyanddemandrefertothebehaviorofpeople.astheyinteractwithoneanotherinmarkets.,Markets,Buyersdeterminedemand.,Sellersdeterminesupply.,MarketType:ACompetitiveMarket,Acompetitivemarketisamarket.,withmanybuyersandsellers.,thatisnotcontrolledbyanyoneperson.,inwhichanarrowrangeofpricesareestablishedthatbuyersandsellersactupon.,Competition:PerfectandOtherwise,ProductsarethesameNumerousbuyersandsellerssothateachhasnoinfluenceoverpriceBuyersandSellersarepricetakers（价格接受者）,PerfectCompetition,Competition:PerfectandOtherwise,Monopoly（完全垄断）Oneseller,andsellercontrolspriceOligopoly（寡头垄断）FewsellersNotalwaysaggressivecompetition,Competition:PerfectandOtherwise,MonopolisticCompetition（垄断竞争）ManysellersSlightlydifferentiatedproductsEachsellermaysetpriceforitsownproduct,Demand,Quantitydemanded（需求量）istheamountofagoodthatbuyersarewillingandabletopurchase.,LawofDemand,Thelawofdemandstatesthatthereisaninverserelationship（负相关）betweenpriceandquantitydemanded.,DemandSchedule（需求表）,Thedemandscheduleisatablethatshowstherelationshipbetweenthepriceofthegoodandthequantitydemanded.,DemandSchedule,Determinants（决定因素）ofDemand,MarketpriceConsumerincomePricesofrelatedgoodsTastesExpectations,DemandCurve（曲线）,Thedemandcurveisthedownward-sloping（向下倾斜的）linerelatingpricetoquantitydemanded.,DemandCurve,$3.00,2.50,2.00,1.50,1.00,0.50,2,1,3,4,5,6,7,8,9,10,12,11,PriceofIce-CreamCone,QuantityofIce-CreamCones,0,CeterisParibus,CeterisparibusisaLatinphrasethatmeansallvariables（变量）otherthantheonesbeingstudiedareassumedtobeconstant.Literally,ceterisparibus（其它情况不变）means“otherthingsbeingequal.”,Thedemandcurveslopesdownwardbecause,ceterisparibus,lowerpricesimply（意味着）agreaterquantitydemanded!,MarketDemand,Marketdemandreferstothesumofallindividualdemandsforaparticulargoodorservice.Graphically（在图形上）,individualdemandcurvesaresummedhorizontally（水平地）toobtainthemarketdemandcurve.,DeterminantsofDemand,MarketpriceConsumerincomePricesofrelatedgoodsTastes（口味）Expectations（预期）,ChangeinQuantityDemandedversusChangeinDemand,ChangeinQuantityDemandedMovementalongthedemandcurve.Causedbyachangeinthepriceoftheproduct.,ChangesinQuantityDemanded,0,D1,PriceofCigarettesperPack,NumberofCigarettesSmokedperDay,Ataxthatraisesthepriceofcigarettesresultsinamovementalongthedemandcurve.,A,20,2.00,ChangeinQuantityDemandedversus（对抗）ChangeinDemand,ChangeinDemandAshiftinthedemandcurve,eithertotheleftorright.Causedbyachangeinadeterminantotherthantheprice.,ChangesinDemand,0,D1,PriceofIce-CreamCone,QuantityofIce-CreamCones,D3,D2,Increaseindemand,Decreaseindemand,ConsumerIncome,Asincomeincreasesthedemandforanormalgood（正常商品）willincrease.Asincomeincreasesthedemandforaninferiorgood（劣品）willdecrease.,ConsumerIncomeNormalGood,$3.00,2.50,2.00,1.50,1.00,0.50,2,1,3,4,5,6,7,8,9,10,12,11,PriceofIce-CreamCone,QuantityofIce-CreamCones,0,Increaseindemand,Anincreaseinincome.,D1,D2,ConsumerIncomeInferiorGood,$3.00,2.50,2.00,1.50,1.00,0.50,2,1,3,4,5,6,7,8,9,10,12,11,PriceofIce-CreamCone,QuantityofIce-CreamCones,0,Decreaseindemand,Anincreaseinincome.,D1,D2,PricesofRelatedGoodsSubstitutes（代替品）&Complements（互补品）,Whenafallinthepriceofonegoodreducesthedemandforanothergood,thetwogoodsarecalledsubstitutes.Whenafallinthepriceofonegoodincreasesthedemandforanothergood,thetwogoodsarecalledcomplements.,ChangeinQuantityDemandedversusChangeinDemand,Supply,Quantitysuppliedistheamountofagoodthatsellersarewillingandabletosell.,LawofSupply,Thelawofsupplystatesthatthereisadirect(positive)relationship（正相关）betweenpriceandquantitysupplied.,DeterminantsofSupply,MarketpriceInput（成本）pricesTechnologyExpectationsNumberofproducers,SupplySchedule,Thesupplyscheduleisatablethatshowstherelationshipbetweenthepriceofthegoodandthequantitysupplied.,SupplySchedule,SupplyCurve,Thesupplycurveistheupward-slopinglinerelatingpricetoquantitysupplied.,SupplyCurve,$3.00,2.50,2.00,1.50,1.00,0.50,2,1,3,4,5,6,7,8,9,10,12,11,PriceofIce-CreamCone,QuantityofIce-CreamCones,0,MarketSupply,Marketsupplyreferstothesumofallindividualsuppliesforallsellersofaparticulargoodorservice.Graphically,individualsupplycurvesaresummedhorizontallytoobtainthemarketsupplycurve.,DeterminantsofSupply,MarketpriceInputpricesTechnologyExpectationsNumberofproducers,ChangeinQuantitySuppliedversusChangeinSupply,ChangeinQuantitySuppliedMovementalongthesupplycurve.Causedbyachangeinthemarketpriceoftheproduct.,ChangeinQuantitySupplied,1,5,PriceofIce-CreamCone,QuantityofIce-CreamCones,0,S,1.00,A,C,Ariseinthepriceoficecreamconesresultsinamovementalongthesupplycurve.,ChangeinQuantitySuppliedversusChangeinSupply,ChangeinSupplyAshiftinthesupplycurve,eithertotheleftorright.Causedbyachangeinadeterminantotherthanprice.,ChangeinSupply,PriceofIce-CreamCone,QuantityofIce-CreamCones,0,S1,ChangeinQuantitySuppliedversusChangeinSupply,SupplyandDemandTogether,Equilibrium（均衡）PriceThepricethatbalancessupplyanddemand.Onagraph,itisthepriceatwhichthesupplyanddemandcurvesintersect.EquilibriumQuantityThequantitythatbalancessupplyanddemand.Onagraphitisthequantityatwhichthesupplyanddemandcurvesintersect.,SupplyandDemandTogether,DemandSchedule,SupplySchedule,At$2.00,thequantitydemandedisequaltothequantitysupplied!,PriceofIce-CreamCone,QuantityofIce-CreamCones,EquilibriumofSupplyandDemand,2,1,3,4,5,6,7,8,9,10,12,11,0,$3.00,2.50,2.00,1.50,1.00,0.50,PriceofIce-CreamCone,QuantityofIce-CreamCones,2,1,3,4,5,6,7,8,9,10,12,11,0,$3.00,2.50,2.00,1.50,1.00,0.50,Supply,Demand,Surplus（剩余）,ExcessSupply（供过于求）,Surplus,Whenthepriceisabovetheequilibriumprice,thequantitysuppliedexceedsthequantitydemanded.Thereisexcesssupplyorasurplus.Supplierswilllowerthepricetoincreasesales,therebymovingtowardequilibrium（均衡）.,ExcessDemand（供不应求）,QuantityofIce-CreamCones,PriceofIce-CreamCone,$2.00,0,1,2,3,4,5,6,7,8,9,10,11,12,13,Supply,Demand,$1.50,Shortage（短缺）,Shortage,Whenthepriceisbelowtheequilibriumprice,thequantitydemandedexceedsthequantitysupplied.Thereisexcessdemandorashortage.Supplierswillraisethepriceduetotoomanybuyerschasingtoofewgoods,therebymovingtowardequilibrium.,ThreeStepsToAnalyzingChangesinEquilibrium,Decidewhethertheeventshiftsthesupplyordemandcurve(orboth).Decidewhetherthecurve(s)shift(s)totheleftortotheright.Examinehowtheshiftaffectsequilibriumpriceandquantity.,HowanIncreaseinDemandAffectstheEquilibrium,PriceofIce-CreamCone,2.00,0,7,QuantityofIce-CreamCones,Supply,Initial（第一个）equilibrium,D1,1.Hotweatherincreasesthedemandforicecream.,Harcourt,Inc.itemsandderiveditemscopyright2001byHarcourt,Inc.,ShiftsinCurvesversusMovementsalongCurves,Ashiftinthesupplycurveiscalledachangeinsupply（供给的变化）.Amovementalongafixedsupplycurveiscalledachangeinquantitysupplied.（供给量的变化）Ashiftinthedemandcurveiscalledachangeindemand.Amovementalongafixeddemandcurveiscalledachangeinquantitydemanded.,HowaDecreaseinSupplyAffectstheEquilibrium,PriceofIce-CreamCone,2.00,0,1,2,3,4,7,8,9,11,12,QuantityofIce-CreamCones,13,Demand,Initialequilibrium,S1,10,1.Anearthquakereducesthesupplyoficecream.,Newequilibrium,WhatHappenstoPriceandQuantityWhenSupplyorDemandShifts?,Summary,Economistsusethemodelofsupplyanddemandtoanalyzecompetitivemarkets.Thedemandcurveshowshowthequantityofagooddependsupontheprice.,Summary,Accordingtothelawofdemand,asthepriceofagoodrises,thequantitydemandedfalls.Inadditiontoprice,otherdeterminantsofquantitydemandedincludeincome,tastes,expectations,andthepricesofcomplementsandsubstitutes.,Summary,Thesupplycurveshowshowthequantityofagoodsupplieddependsupontheprice.Accordingtothelawofsupply,asthepriceofagoodrises,thequantitysuppliedrises.,Summary,Inadditiontoprice,otherdeterminantsofquantitysuppliedincludeinputprices,technology,andexpe