alevel economics 基础 讲义ppt课件

A-LEVELMicroeconomicsbasichttp://blog.sina.com.cn/alevelteaching.*1WhatisEconomicsabout?TheproblemofscarcityEconomicsisthestudyofhowsocietychoosestoallocateitsscarceresourcestotheproductionofgoodsandservicesinordertosatisfyunlimitedwants..Humanwantsareunlimited,butResourcesarelimited(scarce)Acentralproblemthereforeexists…wecallthistheproblemofSCARCITY.*3DefinitionofeconomicsEconomicsisthestudyofsociety’sdecisionsaboutproductionconsumptionallocationofscarceresourcesinordertosatisfyasmanyunlimitedwantsaspossible..*4TwobranchesofeconomicsMicroeconomicsisthebranchofeconomicsthatstudiesdecision-makingbyasingleindividual,household,firm,industryorlevelofgovernment.Macroeconomicsisthebranchofeconomicsthatstudiesdecision-makingfortheeconomyasawhole..*5MacroeconomicIssuesaggregatedemand,aggregatesupplyeconomicgrowthunemploymentinflationbalanceoftradeexchangerates.*6MicroeconomicIssuesdemandandsupplydecisionsofwhattoproduce,howtoproduce,forwhomtoproducetheconceptofopportunitycostbasedoncomparingwhatyouhavedecidedvswhatisthenextbestalternativeyouhavegivenuprationaldecisionmakingbasedoncostvsbenefit;bestvalueformoneyweighingupmarginalcostsandmarginalbenefitsbasedoncomparingtheextrabenefitwiththeextracostthesocialimplicationsofchoicesocietyi.e.takingintoconsiderationhowacertainchoicemayhaveanindirectcoston.ResourcesResourcesarethebasiccategoriesofinputsusedtoproducegoodsandservices.Resourcescanalsobecalledthefactorsofproduction..©2007PearsonEducationAustraliaThreecategoriesofresourcesLandLabourCapital.©2007PearsonEducationAustraliaResources:landAnynaturalresourceprovidedbynatureusedintheprocessofproductionForexample:forests,minerals,wildlife,oil,rivers,lakes,oceansMayberenewableornon-renewable.©2007PearsonEducationAustraliaResources:labourThementalandphysicalcapacityofworkerstoproducegoodsandservicesForexample:farmers,nurses,lawyersEntrepreneurshipisaspecialtypeoflabourthecreativeabilityofindividualstomanagethecombinationofresourcestoproduceproducts..©2007PearsonEducationAustraliaEntrepreneurshipOrganisesandmanagestheresourcesneededtoproducegoodsandservices.©2007PearsonEducationAustraliaResources:capitalCapitalisthephysicalplant,machineryandequipmentusedtoproduceothergoods.Thatis,human-madegoodsthatdonotdirectlysatisfyhumanwants,forexample:Earlier:axe,bowandarrowNow:buildings,productionequipment,software,factories..©2007PearsonEducationAustraliaAnoteaboutfinancialcapitalEconomistsdonotincludemoneyintheirdefinitionofcapitalmoneysimplygivesameasuretothevalueofassets..©2007PearsonEducationAustraliaOpportunitycostThebestalternativesacrificedforachosenalternativeOpportunitycostappliestopersonal,groupandnationaldecision-making,forexampleWhatcouldyoubedoingifyouwerenotcurrentlystudying?Howmanynewroadshavetobeforgoneifthegovernmentspendstaxrevenuesonhomelandsecurity?.©2007PearsonEducationAustraliaMarginalanalysisMarginalanalysisexamineshowthecostsandbenefitschangeinresponsetoincrementalchangesinactions.Anyadditionalactionbyanindividualorafirm,suchasbuyinganadditionalpairofshoesorincreasingproductionofaproductbyanadditionalunit,bringsadditionalcost.Thecentralquestioninmarginalanalysisiswhethertheexpectedbenefitsofthatactionexceedtheaddedcost.©2007PearsonEducationAustraliaMarginalanalysisMarginalanalysishelpsbusinessesandindividualsbalancethecostsandbenefitsofadditionalactions---whethertoproducemore,consumemore,orotherdecisions---anddeterminewhetherthebenefitswillexceedcosts,thusincreasingutility..©2007PearsonEducationAustraliaMarginalanalysisMarginalanalysisbenefitsgovernmentpolicymakers,aswell.Weighingthecostsandbenefitscanhelpgovernmentofficialsdetermineifallocatingadditionalresourcestoaparticularpublicprogramwillgenerateadditionalbenefitsforthegeneralpublic.©2007PearsonEducationAustraliaShort-RunvLongRunShort-Run:Atimeperiodinwhichatleastonefactorofproductionisfixed(i.e.cannotincreaseitsamount)itisnotdefinedintermsofnumberofdays/weeks)LongRun:AtimeperiodlongenoughforallinputstobevariedItisnotadefinedperiodoftime;.©2007PearsonEducationAustraliaCostconceptsTotalfixedcostsarecoststhatdonotvaryasoutputvariesandmustbepaidevenifoutputiszero.Totalvariablecostsarecoststhatarezerowhenoutputiszeroandvaryasoutputvaries.Totalcostisthesumoffixedcostandvariablecost.TC=TFC+TVC.©2007PearsonEducationAustraliaTotalcostsNote:Thexandyaxisunitshereareunrelatedtothepreviousdiagram.©2007PearsonEducationAustraliaAveragecostconceptsAveragefixedcost(AFC)–totalfixedcostdividedbythequantityofoutputproduced:Averagevariablecost(AVC)–totalvariablecostdividedbythequantityofoutputproduced:AFC=TFCAVC=TVCQQ.©2007PearsonEducationAustraliaAveragetotalcostTotalcostdividedbythequantityofoutputproducedATC=AFC+AVC=TCQ.©2007PearsonEducationAustraliaMarginalcostMeasureshowmuchtotalcostincreaseswhenanadditionalunitofoutputisproduced.MC:thechangeintotalcostwhenoneextraunitofoutputisproducedMC=TC=TVCQQ.©2007PearsonEducationAustraliaTotalcosts.©2007PearsonEducationAustraliaInverserelationship:MP&MCNote:Thexandyaxisunitshereareunrelatedtothepreviousdiagram.©2007PearsonEducationAustralia.©2007PearsonEducationAustralia.©2007PearsonEducationAustraliaAverageandmarginalcostsThisgraphusesinformationfromthepreviousslide.©2007PearsonEducationAustraliaNotethemarginal-averageruleWhenMCAC,ACisrising.WhenMC=AC,ACisatitsminimumpoint..©2007PearsonEducationAustraliaLong-runsituationAllfactorsofproductionarevariable.thereistimeforthefirmtobuildanewfactorytoinstallnewmachines,tousedifferentproductiontechniques,tocombineinputsinwhateverproportionandquantitiesitchooses;thefirmwillneedtodecideaboutthescaleofitsoperationandtheproductiontechniquesthatituses;thesedecisionswillaffectproductioncostssoitisimportanttogetthesedecisionsright..©2007PearsonEducationAustraliaRelationbetweenLRACandSRACCurvesAfirmwithjustonefactoryandfacesSRACcurve(followingdiagrams);Inthelong-runitcanbuildmorefactoriesandexperienceseconomiesofscaleduetoadministrativesavings,eachsuccessivefactorywillallowittoproducewithanewlowerSRACcurve;Thuswith2factoriesitwillhavecurveSRAC2andwiththreethenSRAC3,andsoon;EachSRACcurvecorrespondstoaparticularamountofthefactorthatisfixedintheshort-run(inthiscasethefactory);TherearemanySRACcurvesasmanydifferentfactoriesofdifferentsizesorextensionstoexistingonecouldbemade.TheLRACcurveisanENVELOPECURVE.©2007PearsonEducationAustraliaCostsOutputOExamplesofshort-runaveragecostcurvesSRAC2SRAC3SRAC4SRAC5ConstructingaLong-runAverageCostCurvefromShort-runAverageCostCurves.©2007PearsonEducationAustraliaLRACCostsOutputOSRAC5SRAC4SRAC3SRAC2ConstructingaLong-runAverageCostCurvefromShort-runAverageCostCurves.©2007PearsonEducationAustraliaScalesofproductionThelong-runaveragecostcurveisU-shaped.Thisreflectsreturnstoscale–threetypesarerecognised:Economiesofscale(LRACfallsasoutputrises)ConstantreturnstoscaleDiseconomiesofscale(LRACrisesasoutputrises)..©2007PearsonEducationAustraliaScalesofproduction.©2007PearsonEducationAustraliaEconomiesofscaleAsituationinwhichthelong-runaveragecostcurvedeclinesasthefirmincreasesoutputSourcesofeconomiesofscale:SpecialisationandDivisionofLabourGreaterefficiencyoflargermachines(egcombineharvester,‘super’photocopier’.EgmachineAcosts$1000&produces1000unitsdaily.MachineBcosts$4000butcanproduce8000unitsdaily.Unitcostis$1vs$0.50.)ByproductsOrganisationaleconomies(centraliseadminorI.T.supportfunctions;eliminateduplication)Financialeconomies(bulkdiscounts)EconomiesofScope(producingarangeofproductsmayincreasesalesandspreadoutoverheadsEg:CD,DVD,players,amplifiersetcvsonlyCD)(RefertoSlomanp87,88formoreinfo).©2007PearsonEducationAustraliaConstantreturnstoscaleAsituationinwhichthelong-runaveragecostcurvedoesnotchangeasthefirmincreasesoutput..©2007PearsonEducationAustraliaDiseconomiesofscaleAsituationinwhichthelong-runaveragecostcurverisesasthefirmincreasesoutputSourcesofdiseconomiesofscale:BureaucracyBarrierstocommunicationManagementdifficulties(e.g.lackofcoordination).Production-lineprocessesand‘interdependencies’.©2007PearsonEducationAustraliaLong-runCosts“ToScale”meansthatallinputsincreasebythesameproportion’Decreasingreturnstoscalearequitedifferentfromdiminishingmarginalreturns(whereonlythevariablefactorincreases)DMR(short-run)andDRS(long-run).©2007PearsonEducationAustraliaProfitMaximisationSlomanCh5BUECO1507RevenueDefiningtotal,averageandmarginalrevenuetotalrevenue:TR=P×Qaveragerevenue:AR=TR/Qmarginalrevenue:MR=TR/QRevenueRevenuecurveswhenpriceisnotaffectedbythefirm’soutput(horizontaldemandcurve)averagerevenue(AR)marginalrevenue(MR)Examiningrevenuecurvesin2situations1)Ifafirmisverysmallrelativetothewholemarket.2)IfafirmhasarelativelylargeshareofthemarketOOAR,MR($)PeSDD=AR=MRQ(millions)Q(hundreds)(a)ThemarketThefirmBeingsosmall,itsoutput,whateveritis,doesnotaffectmarketpriceatallAverageRevenueandMarginalRevenuecurves(1)ofafirmthatisverySMALLrelativetothewholemarket.(Price-takingfirm)Price($)TRQuantity(units)020040060080010001200Price=AR=MR($)5555555TR($)0100020003000400050006000TotalRevenuecurve(1)ofafirmthatisverySMALLrelativetothewholemarket.(Price-takingfirm)QTR($)Q(units)1234567P=AR($)8765432TR($)8141820201814MR($)6420-2-4MRAR,MR($)QuantityARAverageRevenueandMarginalRevenuecurves(2)ofafirmthathasarelativelyLARGEshareofthewholemarket.Ifsuchafirmwantstosellmore,itcanonlydosobyloweringprice.Ifitchoosestoraiseitsprice,itwillhavetoacceptlowersales.ThereforeAR(price)slopesdownward.HowabouttheMRcurve?Q(units)1234567P=AR($)8765432TR($)8141820201814MR($)6420-2-4MRAR,MR($)QuantityARAverageRevenueandMarginalRevenuecurves(2)ofafirmthathasarelativelyLARGEshareofthewholemarket.Supposingfirmisselling2unitsat$7each.Itcansellthe3rdunitonlybyreducingthepriceofallunitsto$6.Sellingthe3rdunitgains$6butreducingthepriceofunits1&2loses$1x2=$2.MRtherefore=$6-$2=$4TRTR($)Quantity(units)1234567P=AR($)8765432TR($)8141820201814TotalRevenuecurve(2)ofafirmthathasarelativelyLARGEshareofthewholemarket.QuantityRevenuecurvesandpriceelasticityofdemandAR,MR($)QuantityMRARRevenuecurvesandpriceelasticityofdemandRecall:a)Whendemandiselasticandpriceisreduced,totalrevenueincreases.TotalrevenueincreasingmeansMRispositiveb)Whendemandisinelasticandpriceisreduce,totalrevenuedecreases.TotalrevenuedecreasingmeansMRisnegativeTRElasticInelasticTR($)TRCurveforaFirmFacingaDownward-slopingDemandCurveQuantityRevenueRevenuecurveswhenpricevarieswithoutput(downward-slopingdemandcurve)averagerevenue(AR)marginalrevenue(MR)totalrevenue(TR)revenuecurvesandpriceelasticityofdemandShiftsinrevenuecurvesHiddenDetermininga)Outputwhereprofitismaximisedb)Profitatthatoutput1)UsingtotalcurvesmaximisingthedifferencebetweenTRandTC2)UsingmarginalandaveragecurvesTR,TC,TP($)TPTRTCQuantity1)Usingtotalcurvesa)Profitismaximizedwhenoutputis3b)Maximumprofitisd-eQuantityCostsandrevenue($)MRMC2a)Usingmarginalandaveragecurvestodetermineprofitmaximisingoutputa)Profitismaximizedatoutputof3Below3units,thefirmshouldincreaseoutputbecausetherewillbeabiggeradditiontorevenue(MR)thantocost(MC).Beyond3unitsadditionalcost(MC)isbiggerthanadditionalrevenue(MR)thereforeshouldn’tgobeyonditQuantityCostsandrevenue($)MCACARTotalprofit=$1⅓x3=$4.002b)UsingmarginalandaveragecurvestomeasuremaximumprofitTotalProfitMROCostsandrevenue($)QuantityMR2b)UsingmarginalandaveragecurvestodeterminelossminimisingoutputTheshutdownruleIfpricedropsbelowtheAVCcurve,therevenuefromeachunitproduceddoesnotevencoverthevariablecost/sofproduction.Thefirmshouldshutdown.Illustration:(A)(B)(C)(D)Sales$6006060VC(40)0(70)(60)Grossprofit200(10)0FC(30)(30)(30)(30)Loss(10)(30)(40)(30)Theshutdownrule(cont.)(MR)NeedtochangeRevenue,CostsandProfitSomequalificationslong-runprofitmaximisationthemeaningof‘profit’lossminimising:stillproducewhereMR=MCshort-runshut-downpoint:P=AVClong-runshut-downpoint:P=LRACHiddenNormal,Supernormal,EconomicprofitNormalprofit:Theminimumprofitnecessarytokeepafirminoperation(i.e.$85,00intheexample)Afirmthatearnsnormalprofithasearnedenoughtocoveritsopportunitycost.IfyouearnmorethanopportunitycostyouareearningSupernormal(orEconomic)profit.Accountingprofit,Normalprofit,Supernormalprofit,Economicprofit