alevel economics 基础 讲义

A-LEVELMicroeconomicsbasichttp://blog.sina.com.cn/alevelteaching*1WhatisEconomicsabout?Theproblemofscarcity Economicsisthestudyofhowsocietychoosestoallocateitsscarceresourcestotheproductionofgoodsandservicesinordertosatisfyunlimitedwants. Humanwantsareunlimited,but Resourcesarelimited(scarce) Acentralproblemthereforeexists…wecallthistheproblemofSCARCITY *3Definitionofeconomics Economicsisthestudyofsociety’sdecisionsabout production consumption allocationofscarceresources inordertosatisfyasmanyunlimitedwantsaspossible.*4Twobranchesofeconomics Microeconomicsisthebranchofeconomicsthatstudiesdecision-makingbyasingleindividual,household,firm,industryorlevelofgovernment. Macroeconomicsisthebranchofeconomicsthatstudiesdecision-makingfortheeconomyasawhole.*5MacroeconomicIssues aggregatedemand,aggregatesupply economicgrowth unemployment inflation balanceoftrade exchangeratesBUECO1508Ch1Economicissues*DISTINCTIONBETWEENMICROECONOMICSANDMACROECONOMICSMicroElooksatdecision-makingbysingleindividuals,household,firmorindustry.E.g.eggsmarket–ifdemandforeggsgoup,whatistheeffectonprices,howwillsuppliersrespond?MacroElooksattheeconomyasawhole.Notsomuchonindividualfirmsormarketsbutonallofthem(economy).Itconsidersthe“bigpicture”.DD/SSwillbeabouttotallevelofspendingorofproductionoftheeconomy.THEMAJORMACROECONOMICISSUES(moreoftheselaterbutquickglancenow…)1economicgrowth-akanationaloutput,whatisthetotalamountproducedbytheeconomy.2unemployment–asstudentslookingforwork,youwouldhaveafirsthandexperienceofthisexceptthatwelookatanationallevel..%ofthoseinthecountryunemployed…issueofwasteofHR.3inflation(whichisaboutpricelevelof‘everything’ingeneral,notjustschoolfees)4balanceofpaymentsandexchangerates4.1balanceofpaymentsdeficitsandsurplusesa.BPcomparespaymentsTOothercountrieswithpaymentsFROMthem.Exampleof(a)paymentsTO(=DR):imports,investmentsoverseas,interest/dividendspaidtooverseasinvestors.(b)receiptsFROM(=CR):exports,inwardinvestments,dividends,interestb.PaymentsTOusesupFXwhilstreceiptsFROMearnFX.IfpaymentsTOexceedreceiptsFROM….deficit.Viceversa….surplus.4.2exchangeratemovementsa.=rateonecurrencyexchangesforanother.A$1=RMB/Rupee?=US$0.70.b.IfBPofAusconstantlyindeficit,thenratefalls…explanationinCh16.Fallingrate…problem…upspriceofimportsE.g.US$70KUSAcar=A$100KatA$1=US$0.7.Samecar=A$86KifA$1=US$0.60*6MicroeconomicIssues demandandsupplydecisionsofwhattoproduce,howtoproduce,forwhomtoproduce theconceptofopportunitycostbasedoncomparingwhatyouhavedecidedvswhatisthenextbestalternativeyouhavegivenup rationaldecisionmakingbasedoncostvsbenefit;bestvalueformoney weighingupmarginalcostsandmarginalbenefitsbasedoncomparingtheextrabenefitwiththeextracost thesocialimplicationsofchoicesocietyi.e.takingintoconsiderationhowacertainchoicemayhaveanindirectcostonBUECO1508Ch1Economicissues*DISTINCTIONBETWEENMICROECONOMICSANDMACROECONOMICSMicroElooksatdecision-makingbysingleindividuals,household,firmorindustry.E.g.eggsmarket–ifdemandforeggsgoup,whatistheeffectonprices,howwillsuppliersrespond?MacroElooksattheeconomyasawhole.Notsomuchonindividualfirmsormarketsbutonallofthem(economy).Itconsidersthe“bigpicture”.DD/SSwillbeabouttotallevelofspendingorofproductionoftheeconomy.THEMAJORMACROECONOMICISSUES(moreoftheselaterbutquickglancenow…)1economicgrowth-akanationaloutput,whatisthetotalamountproducedbytheeconomy.2unemployment–asstudentslookingforwork,youwouldhaveafirsthandexperienceofthisexceptthatwelookatanationallevel..%ofthoseinthecountryunemployed…issueofwasteofHR.3inflation(whichisaboutpricelevelof‘everything’ingeneral,notjustschoolfees)4balanceofpaymentsandexchangerates4.1balanceofpaymentsdeficitsandsurplusesa.BPcomparespaymentsTOothercountrieswithpaymentsFROMthem.Exampleof(a)paymentsTO(=DR):imports,investmentsoverseas,interest/dividendspaidtooverseasinvestors.(b)receiptsFROM(=CR):exports,inwardinvestments,dividends,interestb.PaymentsTOusesupFXwhilstreceiptsFROMearnFX.IfpaymentsTOexceedreceiptsFROM….deficit.Viceversa….surplus.4.2exchangeratemovementsa.=rateonecurrencyexchangesforanother.A$1=RMB/Rupee?=US$0.70.b.IfBPofAusconstantlyindeficit,thenratefalls…explanationinCh16.Fallingrate…problem…upspriceofimportsE.g.US$70KUSAcar=A$100KatA$1=US$0.7.Samecar=A$86KifA$1=US$0.60Resources 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.TheEntrepreneurislikeamasterchefwhocombinescarrots,peasandcomesupwithawonderfulplateoffriedriceEntrepreneurship OrganisesandmanagestheresourcesneededtoproducegoodsandservicesResources:capital Capitalisthephysicalplant,machineryandequipmentusedtoproduceothergoods.Thatis,human-madegoodsthatdonotdirectlysatisfyhumanwants,forexample: Earlier:axe,bowandarrow Now:buildings,productionequipment,software,factories.Capitalreferstogoodsmadeby‘man’toproduceothergoodsconsumedby‘man’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: Atimeperiodlongenoughforallinputstobevaried Itisnotadefinedperiodoftime; Costconcepts Totalfixedcostsarecosts thatdonotvaryasoutputvariesand mustbepaidevenifoutputiszero. Totalvariablecostsarecosts thatarezerowhenoutputiszeroand varyasoutputvaries. Totalcostisthesumoffixedcostandvariablecost. TC=TFC+TVCTotalcostsNote:ThexandyaxisunitshereareunrelatedtothepreviousdiagramAveragecostconcepts Averagefixedcost(AFC)–totalfixedcostdividedbythequantityofoutputproduced: Averagevariablecost(AVC)–totalvariablecostdividedbythequantityofoutputproduced:AFC=TFCAVC=TVCQQAveragetotalcost TotalcostdividedbythequantityofoutputproducedATC=AFC+AVC=TCQMarginalcost Measureshowmuchtotalcostincreaseswhenanadditionalunitofoutputisproduced. MC:thechangeintotalcostwhenoneextraunitofoutputisproducedMC=TC=TVCQQTotalcostsInverserelationship:MP&MCNote:ThexandyaxisunitshereareunrelatedtothepreviousdiagramAverageandmarginalcostsThisgraphusesinformationfromthepreviousslideNotethemarginal-averagerule WhenMC<AC,ACisfalling. WhenMC>AC,ACisrising. WhenMC=AC,ACisatitsminimumpoint.Long-runsituation Allfactorsofproductionarevariable. thereistimeforthefirmtobuildanewfactory toinstallnewmachines,tousedifferentproductiontechniques, tocombineinputsinwhateverproportionandquantitiesitchooses; thefirmwillneedtodecideaboutthescaleofitsoperationandtheproductiontechniquesthatituses; thesedecisionswillaffectproductioncostssoitisimportanttogetthesedecisionsright.RelationbetweenLRACandSRACCurvesAfirmwithjustonefactoryandfacesSRACcurve(followingdiagrams);Inthelong-runitcanbuildmorefactoriesandexperienceseconomiesofscaleduetoadministrativesavings,eachsuccessivefactorywillallowittoproducewithanewlowerSRACcurve;Thuswith2factoriesitwillhavecurveSRAC2andwiththreethenSRAC3,andsoon;EachSRACcurvecorrespondstoaparticularamountofthefactorthatisfixedintheshort-run(inthiscasethefactory);TherearemanySRACcurvesasmanydifferentfactoriesofdifferentsizesorextensionstoexistingonecouldbemade.TheLRACcurveisanENVELOPECURVECostsOutputOExamplesofshort-runaveragecostcurvesSRAC2SRAC3SRAC4SRAC5ConstructingaLong-runAverageCostCurvefromShort-runAverageCostCurvesLRACCostsOutputOSRAC5SRAC4SRAC3SRAC2ConstructingaLong-runAverageCostCurvefromShort-runAverageCostCurvesScalesofproduction Thelong-runaveragecostcurveis U-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 ThefirmBeingsosmall,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,itcan onlydosobyloweringprice. Ifitchoosestoraiseitsprice,itwillhaveto acceptlowersales.ThereforeAR(price)slopesdownward.HowabouttheMRcurve?Q(units)1234567P=AR($)8765432TR($)8141820201814MR($)6420-2-4MRAR,MR($)QuantityARAverageRevenueandMarginalRevenuecurves(2)ofafirmthathasarelativelyLARGEshareofthewholemarket. Supposingfirmisselling2unitsat$7 each.Itcansellthe3rdunitonlyby reducingthepriceofallunitsto$6. Sellingthe3rdunitgains$6butreducingthe priceofunits1&2loses$1x2=$2.MRtherefore=$6-$2=$4TRTR($)Quantity(units)1234567P=AR($)8765432TR($)8141820201814TotalRevenuecurve(2)ofafirmthathasarelativelyLARGEshareofthewholemarket.QuantityRevenuecurvesandpriceelasticityofdemandAR,MR($)QuantityMRARRevenuecurvesandpriceelasticityofdemandRecall:a)Whendemandiselasticandprice isreduced,totalrevenueincreases. TotalrevenueincreasingmeansMRispositiveb)Whendemandisinelasticandpriceisreduce,totalrevenuedecreases.TotalrevenuedecreasingmeansMRisnegativeTRElasticInelasticTR($)TRCurveforaFirmFacingaDownward-slopingDemandCurveQuantityRevenue Revenuecurveswhenpricevarieswithoutput(downward-slopingdemandcurve) averagerevenue(AR) marginalrevenue(MR) totalrevenue(TR) revenuecurvesandpriceelasticityofdemand ShiftsinrevenuecurvesHiddenDetermininga) Outputwhereprofitismaximisedb) Profitatthatoutput1)Usingtotalcurves maximisingthedifferencebetweenTRandTC2)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)UsingmarginalandaveragecurvestodeterminelossminimisingoutputTheshutdownrule IfpricedropsbelowtheAVCcurve,therevenuefromeachunitproduceddoesnotevencoverthevariablecost/sofproduction. Thefirmshouldshutdown.Illustration: (A) (B) (C) (D)Sales $60 0 60 60VC (40) 0 (70) (60)Grossprofit 20 0 (10) 0FC (30) (30) (30) (30)Loss (10) (30) (40) (30)*Illustration: (A) (B) (C) (D)Sales $60 0 60 60VC (40) 0 (70) (60)Grossprofit 20 0 (10) 0FC (30)(30) (30) (30)Loss (10)(30) (40) (30)Theshutdownrule(cont.)(MR)NeedtochangeRevenue,CostsandProfit Somequalifications long-runprofitmaximisation themeaningof‘profit’ lossminimising:stillproducewhereMR=MC short-runshut-downpoint:P=AVC long-runshut-downpoint:P=LRACHiddenNormal,Supernormal,Economicprofit Normalprofit:Theminimumprofitnecessarytokeepafirminoperation(i.e.$85,00intheexample) Afirmthatearnsnormalprofithasearnedenoughtocoveritsopportunitycost. IfyouearnmorethanopportunitycostyouareearningSupernormal(orEconomic)profit.Accountingprofit,Normalprofit,Supernormalprofit,EconomicprofitBUECO1508Ch1Economicissues*DISTINCTIONBETWEENMICROECONOMICSANDMACROECONOMICSMicroElooksatdecision-makingbysingleindividuals,household,firmorindustry.E.g.eggsmarket–ifdemandforeggsgoup,whatistheeffectonprices,howwillsuppliersrespond?MacroElooksattheeconomyasawhole.Notsomuchonindividualfirmsormarketsbutonallofthem(economy).Itconsidersthe“bigpicture”.DD/SSwillbeabouttotallevelofspendingorofproductionoftheeconomy.THEMAJORMACROECONOMICISSUES(moreoftheselaterbutquickglancenow…)1economicgrowth-akanationaloutput,whatisthetotalamountproducedbytheeconomy.2unemployment–asstudentslookingforwork,youwouldhaveafirsthandexperienceofthisexceptthatwelookatanationallevel..%ofthoseinthecountryunemployed…issueofwasteofHR.3inflation(whichisaboutpricelevelof‘everything’ingeneral,notjustschoolfees)4balanceofpaymentsandexchangerates4.1balanceofpaymentsdeficitsandsurplusesa.BPcomparespaymentsTOothercountrieswithpaymentsFROMthem.Exampleof(a)paymentsTO(=DR):imports,investmentsoverseas,interest/dividendspaidtooverseasinvestors.(b)receiptsFROM(=CR):exports,inwardinvestments,dividends,interestb.PaymentsTOusesupFXwhilstreceiptsFROMearnFX.IfpaymentsTOexceedreceiptsFROM….deficit.Viceversa….surplus.4.2exchangeratemovementsa.=rateonecurrencyexchangesforanother.A$1=RMB/Rupee?=US$0.70.b.IfBPofAusconstantlyindeficit,thenratefalls…explanationinCh16.Fallingrate…problem…upspriceofimportsE.g.US$70KUSAcar=A$100KatA$1=US$0.7.Samecar=A$86KifA$1=US$0.60BUECO1508Ch1Economicissues*DISTINCTIONBETWEENMICROECONOMICSANDMACROECONOMICSMicroElooksatdecision-makingbysingleindividuals,household,firmorindustry.E.g.eggsmarket–ifdemandforeggsgoup,whatistheeffectonprices,howwillsuppliersrespond?MacroElooksattheeconomyasawhole.Notsomuchonindividualfirmsormarketsbutonallofthem(economy).Itconsidersthe“bigpicture”.DD/SSwillbeabouttotallevelofspendingorofproductionoftheeconomy.THEMAJORMACROECONOMICISSUES(moreoftheselaterbutquickglancenow…)1economicgrowth-akanationaloutput,whatisthetotalamountproducedbytheeconomy.2unemployment–asstudentslookingforwork,youwouldhaveafirsthandexperienceofthisexceptthatwelookatanationallevel..%ofthoseinthecountryunemployed…issueofwasteofHR.3inflation(whichisaboutpricelevelof‘everything’ingeneral,notjustschoolfees)4balanceofpaymentsandexchangerates4.1balanceofpaymentsdeficitsandsurplusesa.BPcomparespaymentsTOothercountrieswithpaymentsFROMthem.Exampleof(a)paymentsTO(=DR):imports,investmentsoverseas,interest/dividendspaidtooverseasinvestors.(b)receiptsFROM(=CR):exports,inwardinvestments,dividends,interestb.PaymentsTOusesupFXwhilstreceiptsFROMearnFX.IfpaymentsTOexceedreceiptsFROM….deficit.Viceversa….surplus.4.2exchangeratemovementsa.=rateonecurrencyexchangesforanother.A$1=RMB/Rupee?=US$0.70.b.IfBPofAusconstantlyindeficit,thenratefalls…explanationinCh16.Fallingrate…problem…upspriceofimportsE.g.US$70KUSAcar=A$100KatA$1=US$0.7.Samecar=A$86KifA$1=US$0.60TheEntrepreneurislikeamasterchefwhocombinescarrots,peasandcomesupwithawonderfulplateoffriedriceCapitalreferstogoodsmadeby‘man’toproduceothergoodsconsumedby‘man’*Illustration: (A) (B) (C) (D)Sales $60 0 60 60VC (40) 0 (70) (60)Grossprofit 20 0 (10) 0FC (30)(30) (30) (30)Loss (10)(30) (40) (30)