aleveleconomics基础讲义 经济学 高等教育 教育专区

A-LEVELMicroeconomicsbasic21WhatisEconomicsabout?Theproblemofscarcity?Economicsisthestudyofhowsocietychoosestoallocateitsscarceresourcestotheproductionofgoodsandservicesinordertosatisfyunlimitedwants.?Humanwantsareunlimited,but?Resourcesarelimited(scarce)?Acentralproblemthereforeexists…wecallthistheproblemofSCARCITY43DefinitionofeconomicsEconomicsisthestudyofsociety'sdecisionsabout–production–consumption–allocationofscarceresourcesinordertosatisfyasmanyunlimitedwantsaspossible.54Twobranchesofeconomics?Microeconomicsisthebranchofeconomicsthatstudiesdecision-makingbyasingleindividual,household,firm,industryorlevelofgovernment.?Macroeconomicsisthebranchofeconomicsthatstudiesdecision-makingfortheeconomyasawhole.65MacroeconomicIssues–aggregatedemand,aggregatesupply–economicgrowth–unemployment–inflation–balanceoftrade–exchangerates76MicroeconomicIssues–demandandsupplydecisionsofwhattoproduce,howtoproduce,forwhomtoproduce–theconceptofopportunitycostbasedoncomparingwhatyouhavedecidedvswhatisthenextbestalternativeyouhavegivenup–rationaldecisionmakingbasedoncostvsbenefit;bestvalueformoney–weighingupmarginalcostsandmarginalbenefitsbasedoncomparingtheextrabenefitwiththeextracost–thesocialimplicationsofchoicesocietyi.e.takingintoconsiderationhowacertainchoicemayhaveanindirectcostonResources?Resourcesarethebasiccategoriesofinputsusedtoproducegoodsandservices.?Resourcescanalsobecalledthefactorsofproduction.Threecategoriesofresources?Land?Labour?CapitalResources:land?Anynaturalresourceprovidedbynatureusedintheprocessofproduction?Forexample:forests,minerals,wildlife,oil,rivers,lakes,oceans?Mayberenewableornon-renewableResources:labour?Thementalandphysicalcapacityofworkerstoproducegoodsandservices?Forexample:farmers,nurses,lawyersEntrepreneurshipisaspecialtypeoflabour?thecreativeabilityofindividualstomanagethecombinationofresourcestoproduceproducts.Entrepreneurship?OrganisesandmanagestheresourcesneededtoproducegoodsandservicesResources:capital?Capitalisthephysicalplant,machineryandequipmentusedtoproduceothergoods.Thatis,human-madegoodsthatdonotdirectlysatisfyhumanwants,forexample:?Earlier:axe,bowandarrow?Now:buildings,productionequipment,software,factories.Anoteaboutfinancialcapital?Economistsdonotincludemoneyintheirdefinitionofcapital?moneysimplygivesameasuretothevalueofassets.Opportunitycost?Thebestalternativesacrificedforachosenalternative?Opportunitycostappliestopersonal,groupandnationaldecision-making,forexample?Whatcouldyoubedoingifyouwerenotcurrentlystudying??Howmanynewroadshavetobeforgoneifthegovernmentspendstaxrevenuesonhomelandsecurity?Marginalanalysis?Marginalanalysisexamineshowthecostsandbenefitschangeinresponsetoincrementalchangesinactions.?Anyadditionalactionbyanindividualorafirm,suchasbuyinganadditionalpairofshoesorincreasingproductionofaproductbyanadditionalunit,bringsadditionalcost.?ThecentralquestioninmarginalanalysisiswhethertheexpectedbenefitsofthatactionexceedtheaddedcostMarginalanalysis?Marginalanalysishelpsbusinessesandindividualsbalancethecostsandbenefitsofadditionalactions---whethertoproducemore,consumemore,orotherdecisions---anddeterminewhetherthebenefitswillexceedcosts,thusincreasingutility.Marginalanalysis?Marginalanalysisbenefitsgovernmentpolicymakers,aswell.?WeighingthecostsandbenefitscanhelpgovernmentofficialsdetermineifallocatingadditionalresourcestoaparticularpublicprogramwillgenerateadditionalbenefitsforthegeneralpublicShort-RunvLongRun?Short-Run:Atimeperiodinwhichatleastonefactorofproductionisfixed(i.e.cannotincreaseitsamount)itisnotdefinedintermsofnumberofdays/weeks)?LongRun:AtimeperiodlongenoughforallinputstobevariedItisnotadefinedperiodoftime;Costconcepts?Totalfixedcostsarecosts–thatdonotvaryasoutputvariesand–mustbepaidevenifoutputiszero.?Totalvariablecostsarecosts–thatarezerowhenoutputiszeroand–varyasoutputvaries.?Totalcostisthesumoffixedcostandvariablecost.TC=TFC+TVCTotalcostsNote:ThexandyaxisunitshereareunrelatedtothepreviousdiagramAveragecostconcepts?Averagefixedcost(AFC)–totalfixedcostdividedbythequantityofoutputproduced:?Averagevariablecost(AVC)–totalvariablecostdividedbythequantityofoutputproduced:QQAveragetotalcost?TotalcostdividedbythequantityofoutputproducedATC=AFC+AVC=TCQMarginalcost?Measureshowmuchtotalcostincreaseswhenanadditionalunitofoutputisproduced.MC:thechangeintotalcostwhenoneextraunitofoutputisproducedMC=?TC=?TVC?Q?QTotalcostsInverserelationship:MP&MCNote:ThexandyaxisunitshereareunrelatedtothepreviousdiagramAverageandmarginalcostsThisgraphusesinformationfromthepreviousslideNotethemarginal-averagerule?WhenMCAC,ACisrising.?WhenMC=AC,ACisatitsminimumpoint.Long-runsituation?Allfactorsofproductionarevariable.–thereistimeforthefirmtobuildanewfactory–toinstallnewmachines,tousedifferentproductiontechniques,–tocombineinputsinwhateverproportionandquantitiesitchooses;?thefirmwillneedtodecideaboutthescaleofitsoperationandtheproductiontechniquesthatituses;?thesedecisionswillaffectproductioncostssoitisimportanttogetthesedecisionsright.RelationbetweenLRACandSRACCurves●AfirmwithjustonefactoryandfacesSRACcurve(followingdiagrams);●Inthelong-runitcanbuildmorefactoriesandexperienceseconomiesofscaleduetoadministrativesavings,eachsuccessivefactorywillallowittoproducewithanewlowerSRACcurve;●Thuswith2factoriesitwillhavecurveSRAC2andwiththreethenSRAC3,andsoon;●EachSRACcurvecorrespondstoaparticularamountofthefactorthatisfixedintheshort-run(inthiscasethefactory);●TherearemanySRACcurvesasmanydifferentfactoriesofdifferentsizesorextensionstoexistingonecouldbemade.●TheLRACcurveisanENVELOPECURVECostsOutputOExamplesofshort-runaveragecostcurvesSRAC1SRAC2SRAC3SRAC4SRAC5ConstructingaLong-runAverageCostCurvefromShort-runAverageCostCurvesLRACCostsOutputOSRAC5SRAC4SRAC3SRAC2SRAC1ConstructingaLong-runAverageCostCurvefromShort-runAverageCostCurvesScalesofproduction?Thelong-runaveragecostcurveisU-shaped.?Thisreflectsreturnstoscale–threetypesarerecognised:–Economiesofscale(LRACfallsasoutputrises)–Constantreturnstoscale–Diseconomiesofscale(LRACrisesasoutputrises).ScalesofproductionEconomiesofscale?Asituationinwhichthelong-runaveragecostcurvedeclinesasthefirmincreasesoutput?Sourcesofeconomiesofscale:–SpecialisationandDivisionofLabour–Greaterefficiencyoflargermachines(egcombineharvester,‘super'photocopier'.EgmachineAcosts$1000&produces1000unitsdaily.MachineBcosts$4000butcanproduce8000unitsdaily.Unitcostis$1vs$0.50.)–Byproducts–Organisationaleconomies(centraliseadminorI.T.supportfunctions;eliminateduplication)–Financialeconomies(bulkdiscounts)?EconomiesofScope(producingarangeofproductsmayincreasesalesandspreadoutoverheadsEg:CD,DVD,players,amplifiersetcvsonlyCD)(RefertoSlomanp87,88formoreinfo)Constantreturnstoscale?Asituationinwhichthelong-runaveragecostcurvedoesnotchangeasthefirmincreasesoutput.Diseconomiesofscale?Asituationinwhichthelong-runaveragecostcurverisesasthefirmincreasesoutput?Sourcesofdiseconomiesofscale:–Bureaucracy–Barrierstocommunication–Managementdifficulties(e.g.lackofcoordination).–Production-lineprocessesand‘interdependencies'Long-runCosts?“ToScale”meansthatallinputsincreasebythesameproportion'?Decreasingreturnstoscalearequitedifferentfromdiminishingmarginalreturns(whereonlythevariablefactorincreases)?DMR(short-run)andDRS(long-run)ProfitMaximisationSlomanCh5BUECO1507Revenue?Definingtotal,averageandmarginalrevenue–totalrevenue:TR=P×Q–averagerevenue:AR=TR/Q–marginalrevenue:MR=?TR/?QRevenue?Revenuecurveswhenpriceisnotaffectedbythefirm'soutput(horizontaldemandcurve)–averagerevenue(AR)–marginalrevenue(MR)Examiningrevenuecurvesin2situations1)Ifafirmisverysmallrelativetothewholemarket.2)IfafirmhasarelativelylargeshareofthemarketOOAR,MR($)PeSDD=AR=MRQ(millions)Q(hundreds)(a)Themarket(b)ThefirmBeingsosmall,itsoutput,whateveritis,doesnotaffectmarketpriceatallAverageRevenueandMarginalRevenuecurves(1)ofafirmthatisverySMALLrelativetothewholemarket.(Price-takingfirm)Price($)0100020003000400050006000020040060080010001200TRQuantity(units)020040060080010001200Price=AR=MR($)5555555TR($)0100020003000400050006000TotalRevenuecurve(1)ofafirmthatisverySMALLrelativetothewholemarket.(Price-takingfirm)QTR($)-4-2024681234567Q(units)1234567P=AR($)8765432TR($)8141820201814MR($)6420-2-4MRAR,MR($)QuantityARAverageRevenueandMarginalRevenuecurves(2)ofafirmthathasarelativelyLARGEshareofthewholemarket.?Ifsuchafirmwantstosellmore,itcanonlydosobyloweringprice.?Ifitchoosestoraiseitsprice,itwillhavetoacceptlowersales.ThereforeAR(price)slopesdownward.HowabouttheMRcurve?-4-2024681234567Q(units)1234567P=AR($)8765432TR($)8141820201814MR($)6420-2-4MRAR,MR($)QuantityARAverageRevenueandMarginalRevenuecurves(2)ofafirmthathasarelativelyLARGEshareofthewholemarket.?Supposingfirmisselling2unitsat$7each.Itcansellthe3rdunitonlybyreducingthepriceofallunitsto$6.?Sellingthe3rdunitgains$6butreducingthepriceofunits1&2loses$1x2=$2.MRtherefore=$6-$2=$404812162001234567TRTR($)Quantity(units)1234567P=AR($)8765432TR($)8141820201814TotalRevenuecurve(2)ofafirmthathasarelativelyLARGEshareofthewholemarket.QuantityRevenuecurvesandpriceelasticityofdemand-4-2024681234567Elasticity=-1Elastic(a)Inelastic(b)AR,MR($)QuantityMRARRevenuecurvesandpriceelasticityofdemandRecall:a)Whendemandiselasticandpriceisreduced,totalrevenueincreases.TotalrevenueincreasingmeansMRispositiveb)Whendemandisinelasticandpriceisreduce,totalrevenuedecreases.TotalrevenuedecreasingmeansMRisnegative04812162001234567TRElasticity=-1TR($)TRCurveforaFirmFacingaDownward-slopingDemandCurveQuantityDetermininga)Outputwhereprofitismaximisedb)Profitatthatoutput1)Usingtotalcurves–maximisingthedifferencebetweenTRandTC2)UsingmarginalandaveragecurvesTR,TC,TP($)TPTRTCdefQuantity-8-6-4-202468101214161820222412345671)Usingtotalcurvesa)Profitismaximizedwhenoutputis3b)Maximumprofitisd-e-404812161234567QuantityCostsandrevenue($)eMRMCProfit-maximisingoutput2a)Usingmarginalandaveragecurvestodetermineprofitmaximisingoutputa)Profitismaximizedatoutputof3Below3units,thefirmshouldincreaseoutputbecausetherewillbeabiggeradditiontorevenue(MR)thantocost(MC).Beyond3unitsadditionalcost(MC)isbiggerthanadditionalrevenue(MR)thereforeshouldn'tgobeyondit6.004?-404812161234567QuantityCostsandrevenue($)MCACARbaTotalprofit=$1?x3=$4.002b)UsingmarginalandaveragecurvestomeasuremaximumprofitTotalProfitMRLOSSOCostsandrevenue($)QuantityMCACARMRQACAR2b)UsingmarginalandaveragecurvestodeterminelossminimisingoutputTheshutdownrule?IfpricedropsbelowtheAVCcurve,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)Normal,Supernormal,Economicprofit?Normalprofit:Theminimumprofitnecessarytokeepafirminoperation(i.e.$85,00intheexample)?Afirmthatearnsnormalprofithasearnedenoughtocoveritsopportunitycost.?IfyouearnmorethanopportunitycostyouareearningSupernormal(orEconomic)profit.ITEMACCOUNTINGPROFITECONOMICPROFITTotalRevenueWagesMaterialsInterestpaidOtherpaymentsLessforegoneprofitfromnextbestalternativeEqualsprofit$555,000400,00050,00010,00010,000Lessprofitforegonefromnextbestalternative$85,000$555,000400,00050,00010,00010,00085,0000Accountingprofit,Normalprofit,Supernormalprofit,Economicprofit