经济学基础opt10 4E

Whenyouhavecompletedyourstudyofthischapter,youwillbeabletoCHAPTERCHECKLISTExplainhoweconomistsmeasureafirm’scostofproductionandprofit.1Explaintherelationshipbetweenafirm’soutputandlaboremployedintheshortrun.2Explaintherelationshipbetweenafirm’soutputandcostsintheshortrun.3Deriveandexplainafirm’slong-runaveragecostcurve.4生产要素与生产函数生产要素包括生产中使用的各种资源。但在经济学中概括为劳动、土地、资本与企业家才能。生产函数是指生产要素投入量与产量之间的关系。Q=F(L,K,N,E)Q=F(L,K)柯布——道格拉斯生产函数土地资本q=AKaL1-a给定产量9.1ECONOMICCOSTANDPROFITTheFirm’sGoalTomaximizeprofitAccountingCostandProfitAnaccountantmeasurescostandprofittoensurethatthefirmpaysthecorrectamountofincometaxandtoshowthebankhowthefirmhasuseditsbankloan.Economistspredictthedecisionsthatafirmmakestomaximizeitsprofit.Thesedecisionsrespondtoopportunitycostandeconomicprofit.9.1ECONOMICCOSTANDPROFITOpportunityCostThehighest-valuedalternativeforgoneistheopportunitycostofafirm’sproduction.9.1ECONOMICCOSTANDPROFITExplicitCostsandImplicitCostsExplicitcostAcostpaidinmoney.ImplicitcostAnopportunitycostincurredbyafirmwhenitusesafactorofproductionforwhichitdoesnotmakeadirectmoneypayment.Thetwomainimplicitcostsareeconomicdepreciationandthecostofthefirmowner’sresources.9.1ECONOMICCOSTANDPROFITEconomicdepreciationTheopportunitycostofafirmusingcapitalthatitowns—measuredasthechangeinthemarketvalueofcapitaloveragivenperiod.NormalprofitThereturntoentrepreneurship.Normalprofitispartofafirm’sopportunitycostbecauseitisthecostoftheentrepreneurnotrunninganotherfirm.9.1ECONOMICCOSTANDPROFITEconomicProfitAfirm’seconomicprofitequalstotalrevenueminustotalcost.Totalcostisthesumoftheexplicitcostsandimplicitcostsandistheopportunitycostofproduction.Becausethefirm’sopportunitycostofproductionincludesnormalprofit,thereturntotheentrepreneurequalsnormalprofitpluseconomicprofit.Ifafirmincursaneconomicloss,theentrepreneurreceiveslessthannormalprofit.9.1ECONOMICCOSTANDPROFIT9.1ECONOMICCOSTANDPROFITFigure9.1showstwoviewsofcostandprofit.Economistsmeasurecostasthesumofexplicitcostsandimplicitcosts,whichequalsopportunitycost.9.1ECONOMICCOSTANDPROFITNormalprofitisanimplicitcost.Accountantsmeasurecostasexplicitcostsandaccountingdepreciation.9.1ECONOMICCOSTANDPROFITEconomicprofitequalstotalrevenueminusopportunitycost.Accountingprofitequalstotalrevenueminusaccountingcost.TheShortRun:FixedPlantTheshortrunisatimeframeinwhichthequantitiesofsomeresourcesarefixed.Intheshortrun,afirmcanusuallychangethequantityoflaboritusesbutnotthequantityofcapitalTheLongRun:VariablePlantThelongrunisatimeframeinwhichthequantitiesofallresourcescanbechanged.Asunkcostisirrelevanttothefirm’sdecisions.SHORTRUNANDLONGRUN9.2SHORT-RUNPRODUCTIONToincreaseoutputwithafixedplant,afirmmustincreasethequantityoflaborituses.Wedescribetherelationshipbetweenoutputandthequantityoflaborbyusingthreerelatedconcepts:•Totalproduct•Marginalproduct•Averageproduct9.2SHORT-RUNPRODUCTIONTotalProductTotalproduct(TP)isthetotalquantityofagoodproducedinagivenperiod.Totalproductisanoutputrate—thenumberofunitsproducedperunitoftime.Totalproductincreasesasthequantityoflaboremployedincreases.9.2SHORT-RUNPRODUCTIONFigure9.2showsthetotalproductandthetotalproductcurve.PointsAthroughHonthecurvecorrespondtothecolumnsofthetable.TheTPcurveislikethePPF:Itseparatesattainablepointsandunattainablepoints.9.2SHORT-RUNPRODUCTIONMarginalProductMarginalproductisthechangeintotalproductthatresultsfromaone-unitincreaseinthequantityoflaboremployed.Ittellsusthecontributiontototalproductofaddingonemoreworker.Whenthequantityoflaborincreasesbymore(orless)thanoneworker,calculatemarginalproductas:MarginalproductChangeintotalproductChangeinquantityoflabor=9.2SHORT-RUNPRODUCTIONFigure9.3showstotalproductandmarginalproduct.Wecanillustratemarginalproductastheorangebarsthatformstepsalongthetotalproductcurve.Theheightofeachsteprepresentsmarginalproduct.Thetablecalculatesmarginalproductandtheorangebarsinpart(b)illustrateit.NoticethatthesteepertheslopeoftheTPcurve,thegreaterismarginalproduct.9.2SHORT-RUNPRODUCTIONThetotalproductandmarginalproductcurvesinthisfigureincorporateafeatureofallproductionprocesses:•Increasingmarginalreturnsinitially•Decreasingmarginalreturnseventually•Negativemarginalreturns9.2SHORT-RUNPRODUCTION9.2SHORT-RUNPRODUCTIONIncreasingMarginalReturnsIncreasingmarginalreturnsoccurwhenthemarginalproductofanadditionalworkerexceedsthemarginalproductofthepreviousworker.Increasingmarginalreturnsoccurwhenasmallnumberofworkersareemployedandarisefromincreasedspecializationanddivisionoflaborintheproductionprocess.9.2SHORT-RUNPRODUCTIONDecreasingMarginalReturnsDecreasingmarginalreturnsoccurwhenthemarginalproductofanadditionalworkerislessthanthemarginalproductofthepreviousworker.Decreasingmarginalreturnsarisefromthefactthatmoreandmoreworkersusethesameequipmentandworkspace.Asmoreworkersareemployed,thereislessandlessthatisproductivefortheadditionalworkertodo.9.2SHORT-RUNPRODUCTIONDecreasingmarginalreturnsaresopervasivethattheyqualifyforthestatusofalaw:Thelawofdecreasingreturnsstatesthat:Asafirmusesmoreofavariableinput,withagivenquantityoffixedinputs,t