alevel economics 基础 讲义PPT课件.ppt

A LEVELMicroeconomicsbasic 2020 4 8 1 2 1WhatisEconomicsabout Theproblemofscarcity Economicsisthestudyofhowsocietychoosestoallocateitsscarceresourcestotheproductionofgoodsandservicesinordertosatisfyunlimitedwants 2020 4 8 2 Humanwantsareunlimited butResourcesarelimited scarce Acentralproblemthereforeexists wecallthistheproblemofSCARCITY 2020 4 8 3 4 3Definitionofeconomics Economicsisthestudyofsociety sdecisionsaboutproductionconsumptionallocationofscarceresourcesinordertosatisfyasmanyunlimitedwantsaspossible 2020 4 8 4 5 4Twobranchesofeconomics Microeconomicsisthebranchofeconomicsthatstudiesdecision makingbyasingleindividual household firm industryorlevelofgovernment Macroeconomicsisthebranchofeconomicsthatstudiesdecision makingfortheeconomyasawhole 2020 4 8 5 6 5MacroeconomicIssues aggregatedemand aggregatesupplyeconomicgrowthunemploymentinflationbalanceoftradeexchangerates 2020 4 8 6 7 6MicroeconomicIssues demandandsupplydecisionsofwhattoproduce howtoproduce forwhomtoproducetheconceptofopportunitycostbasedoncomparingwhatyouhavedecidedvswhatisthenextbestalternativeyouhavegivenuprationaldecisionmakingbasedoncostvsbenefit bestvalueformoneyweighingupmarginalcostsandmarginalbenefitsbasedoncomparingtheextrabenefitwiththeextracostthesocialimplicationsofchoicesocietyi e takingintoconsiderationhowacertainchoicemayhaveanindirectcoston 2020 4 8 7 Resources Resourcesarethebasiccategoriesofinputsusedtoproducegoodsandservices Resourcescanalsobecalledthefactorsofproduction Threecategoriesofresources LandLabourCapital Resources land AnynaturalresourceprovidedbynatureusedintheprocessofproductionForexample forests minerals wildlife oil rivers lakes oceansMayberenewableornon renewable Resources labour ThementalandphysicalcapacityofworkerstoproducegoodsandservicesForexample farmers nurses lawyersEntrepreneurshipisaspecialtypeoflabour thecreativeabilityofindividualstomanagethecombinationofresourcestoproduceproducts Entrepreneurship Organisesandmanagestheresourcesneededtoproducegoodsandservices Resources capital Capitalisthephysicalplant machineryandequipmentusedtoproduceothergoods Thatis human madegoodsthatdonotdirectlysatisfyhumanwants forexample Earlier axe bowandarrowNow buildings productionequipment software factories Anoteaboutfinancialcapital Economistsdonotincludemoneyintheirdefinitionofcapital moneysimplygivesameasuretothevalueofassets Opportunitycost ThebestalternativesacrificedforachosenalternativeOpportunitycostappliestopersonal groupandnationaldecision making forexampleWhatcouldyoubedoingifyouwerenotcurrentlystudying Howmanynewroadshavetobeforgoneifthegovernmentspendstaxrevenuesonhomelandsecurity Marginalanalysis Marginalanalysisexamineshowthecostsandbenefitschangeinresponsetoincrementalchangesinactions Anyadditionalactionbyanindividualorafirm suchasbuyinganadditionalpairofshoesorincreasingproductionofaproductbyanadditionalunit bringsadditionalcost Thecentralquestioninmarginalanalysisiswhethertheexpectedbenefitsofthatactionexceedtheaddedcost Marginalanalysis Marginalanalysishelpsbusinessesandindividualsbalancethecostsandbenefitsofadditionalactions whethertoproducemore consumemore orotherdecisions anddeterminewhetherthebenefitswillexceedcosts thusincreasingutility Marginalanalysis Marginalanalysisbenefitsgovernmentpolicymakers aswell Weighingthecostsandbenefitscanhelpgovernmentofficialsdetermineifallocatingadditionalresourcestoaparticularpublicprogramwillgenerateadditionalbenefitsforthegeneralpublic Short RunvLongRun Short Run Atimeperiodinwhichatleastonefactorofproductionisfixed i e cannotincreaseitsamount itisnotdefinedintermsofnumberofdays weeks LongRun AtimeperiodlongenoughforallinputstobevariedItisnotadefinedperiodoftime Costconcepts Totalfixedcostsarecoststhatdonotvaryasoutputvariesandmustbepaidevenifoutputiszero Totalvariablecostsarecoststhatarezerowhenoutputiszeroandvaryasoutputvaries Totalcostisthesumoffixedcostandvariablecost TC TFC TVC Totalcosts Note Thexandyaxisunitshereareunrelatedtothepreviousdiagram Averagecostconcepts Averagefixedcost AFC totalfixedcostdividedbythequantityofoutputproduced Averagevariablecost AVC totalvariablecostdividedbythequantityofoutputproduced AFC TFC AVC TVC Q Q Averagetotalcost Totalcostdividedbythequantityofoutputproduced ATC AFC AVC TC Q Marginalcost Measureshowmuchtotalcostincreaseswhenanadditionalunitofoutputisproduced MC thechangeintotalcostwhenoneextraunitofoutputisproduced MC TC TVC Q Q Totalcosts Inverserelationship MP MC Note Thexandyaxisunitshereareunrelatedtothepreviousdiagram Averageandmarginalcosts Thisgraphusesinformationfromthepreviousslide Notethemarginal averagerule WhenMCAC ACisrising WhenMC AC ACisatitsminimumpoint Long runsituation Allfactorsofproductionarevariable thereistimeforthefirmtobuildanewfactorytoinstallnewmachines tousedifferentproductiontechniques tocombineinputsinwhateverproportionandquantitiesitchooses thefirmwillneedtodecideaboutthescaleofitsoperationandtheproductiontechniquesthatituses thesedecisionswillaffectproductioncostssoitisimportanttogetthesedecisionsright RelationbetweenLRACandSRACCurves AfirmwithjustonefactoryandfacesSRACcurve followingdiagrams Inthelong runitcanbuildmorefactoriesandexperienceseconomiesofscaleduetoadministrativesavings eachsuccessivefactorywillallowittoproducewithanewlowerSRACcurve Thuswith2factoriesitwillhavecurveSRAC2andwiththreethenSRAC3 andsoon EachSRACcurvecorrespondstoaparticularamountofthefactorthatisfixedintheshort run inthiscasethefactory TherearemanySRACcurvesasmanydifferentfactoriesofdifferentsizesorextensionstoexistingonecouldbemade TheLRACcurveisanENVELOPECURVE Costs Output O Examplesofshort runaveragecostcurves SRAC2 SRAC3 SRAC4 SRAC5 ConstructingaLong runAverageCostCurvefromShort runAverageCostCurves LRAC Costs Output O SRAC5 SRAC4 SRAC3 SRAC2 ConstructingaLong runAverageCostCurvefromShort runAverageCostCurves Scalesofproduction Thelong runaveragecostcurveisU shaped Thisreflectsreturnstoscale threetypesarerecognised Economiesofscale LRACfallsasoutputrises ConstantreturnstoscaleDiseconomiesofscale LRACrisesasoutputrises Scalesofproduction Economiesofscale Asituationinwhichthelong runaveragecostcurvedeclinesasthefirmincreasesoutputSourcesofeconomiesofscale SpecialisationandDivisionofLabourGreaterefficiencyoflargermachines egcombineharvester super photocopier EgmachineAcosts 1000eliminateduplication Financialeconomies bulkdiscounts EconomiesofScope producingarangeofproductsmayincreasesalesandspreadoutoverheadsEg CD DVD players amplifiersetcvsonlyCD RefertoSlomanp87 88formoreinfo Constantreturnstoscale Asituationinwhichthelong runaveragecostcurvedoesnotchangeasthefirmincreasesoutput Diseconomiesofscale Asituationinwhichthelong runaveragecostcurverisesasthefirmincreasesoutputSourcesofdiseconomiesofscale BureaucracyBarrierstocommunicationManagementdifficulties e g lackofcoordination Production lineprocessesand interdependencies Long runCosts ToScale meansthatallinputsincreasebythesameproportion Decreasingreturnstoscalearequitedifferentfromdiminishingmarginalreturns whereonlythevariablefactorincreases DMR short run andDRS long run ProfitMaximisationSlomanCh5 BUECO1507 Revenue Definingtotal averageandmarginalrevenuetotalrevenue TR P Qaveragerevenue AR TR Qmarginalrevenue MR TR Q Revenue Revenuecurveswhenpriceisnotaffectedbythefirm soutput horizontaldemandcurve averagerevenue AR marginalrevenue MR Examiningrevenuecurvesin2situations 1 Ifafirmisverysmallrelativetothewholemarket 2 Ifafirmhasarelativelylargeshareofthemarket O O AR MR Pe S D D AR MR Q millions Q hundreds a Themarket ThefirmBeingsosmall itsoutput whateveritis doesnotaffectmarketpriceatall AverageRevenueandMarginalRevenuecurves 1 ofafirmthatisverySMALLrelativetothewholemarket Price takingfirm Price TR Quantity units 020040060080010001200 Price AR MR 5555555 TR 0100020003000400050006000 TotalRevenuecurve 1 ofafirmthatisverySMALLrelativetothewholemarket Price takingfirm Q TR Q units 1234567 P AR 8765432 TR 8141820201814 MR 6420 2 4 MR AR MR Quantity AR AverageRevenueandMarginalRevenuecurves 2 ofafirmthathasarelativelyLARGEshareofthewholemarket Ifsuchafirmwantstosellmore itcanonlydosobyloweringprice Ifitchoosestoraiseitsprice itwillhavetoacceptlowersales ThereforeAR price slopesdownward HowabouttheMRcurve Q units 1234567 P AR 8765432 TR 8141820201814 MR 6420 2 4 MR AR MR Quantity AR AverageRevenueandMarginalRevenuecurves 2 ofafirmthathasarelativelyLARGEshareofthewholemarket Supposingfirmisselling2unitsat 7each Itcansellthe3rdunitonlybyreducingthepriceofallunitsto 6 Sellingthe3rdunitgains 6butreducingthepriceofunits1 2loses 1x2 2 MRtherefore 6 2 4 TR TR Quantity units 1234567 P AR 8765432 TR 8141820201814 TotalRevenuecurve 2 ofafirmthathasarelativelyLARGEshareofthewholemarket Quantity Revenuecurvesandpriceelasticityofdemand AR MR Quantity MR AR Revenuecurvesandpriceelasticityofdemand Recall a Whendemandiselasticandpriceisreduced totalrevenueincreases TotalrevenueincreasingmeansMRispositiveb Whendemandisinelasticandpriceisreduce totalrevenuedecreases TotalrevenuedecreasingmeansMRisnegative TR Elastic Inelastic TR TRCurveforaFirmFacingaDownward slopingDemandCurve Quantity Revenue Revenuecurveswhenpricevarieswithoutput downward slopingdemandcurve averagerevenue AR marginalrevenue MR totalrevenue TR revenuecurvesandpriceelasticityofdemandShiftsinrevenuecurves Hidden Determininga Outputwhereprofitismaximisedb Profitatthatoutput 1 UsingtotalcurvesmaximisingthedifferencebetweenTRandTC2 Usingmarginalandaveragecurves TR TC TP TP TR TC Quantity 1 Usingtotalcurves a Profitismaximizedwhenoutputis3b Maximumprofitisd e Quantity Costsandrevenue MR MC 2a Usingmarginalandaveragecurvestodetermineprofitmaximisingoutput a Profitismaximizedatoutputof3Below3units thefirmshouldincreaseoutputbecausetherewillbeabiggeradditiontorevenue MR thantocost MC Beyond3unitsadd