1StevenLandsburg,UniversityofRochesterChapter6ProductionandCostsCopyright?2005byThomsonSouth-Western,partoftheThomsonCorporation.Allrightsreserved.2Introduction生產(chǎn)函數(shù)決定成本函數(shù)，而(邊際)成本會影響供給函數(shù)；因此，本章先介紹生產(chǎn)函數(shù)，然後說明成本函數(shù)。生產(chǎn)函數(shù)在說明生產(chǎn)要素與產(chǎn)量之間的關係；生產(chǎn)要素分為兩類，一類是短期即可變動其使用的數(shù)量的(以勞工為代表)，另一類是長期才可變動其使用的數(shù)量的(以資本為代表)。產(chǎn)量受到生產(chǎn)技術(shù)與生產(chǎn)要素的影響WheredocostcurvescomefromDependsonfirm’savailabletechnologyDeterminesproductionprocessProductionprocessdeterminesfirm’scosts3ProductionandCostsintheShortRunLimitedoptionsinshortrun(SR)InitialassumptionFirmcanhiremorelabor4ProductionintheShortRunTotalproduct(TP)oflaborQuantityofoutputproducedbyfirminagivenamountoftimedependentonlaborhiredInformationgraphicallyrepresentedbyproductionfunctionProductionfunctionslopesupwardProductionfunctionisrulefordetermininghowmuchoutputcanbeproducedwithagivenbasketofinputs5CalculatingMPandAPMarginalproductoflabor(MPL)IncreaseintotalproductbasedonhiringoneadditionalworkerAssumecapitalfixedSlopeofTPAverageproductoflabor(APL)Totalproductdividedbynumberofworkers6RelationbetweenMPandAPNTP7CalculatingMPandAP8MPL&APL9EXHIBIT6.1 Total,MarginalandAverageProducts10ShapeofMPandAPCurvesAP Ifnumberofworkerslarge,additionalworkerscauseaverageproductoflabortodecreaseInvertedU-shapeMPInvertedU-shapeAPandMPrelationshiptooneanotherIfMP>AP,MPliesaboveAPIfMP<AP,MPliesbelowAPIfMP=AP,APatmaximumorpeak11EXHIBIT6.2TheStagesofProduction12VariableCostsintheSRConstructingthefirm’svariablecostcurveNeedtotalproductcurveNeedwageratePriceofhiringlaborMultiplynumberofworkersbywageratetogetvariablecostPL×L=VCCurverelatestotalproduct,notnumberofworkers,tovariablecost13Exhibit6.3VCCurveNTPQVCTC15515652121230803212145954282860110533337512563636901407373710515514EXHIBIT6.3VariableCostCurve15FixedCostsintheSRCostsofcapitalPhysicalassets,suchasmachineryandfactoriesEx.handyman’’svan16TotalCostTotalcostequaltosumoffixedandvariablecostsofproductionTC=FC+VC=FC+PL×LAdditionalcostconsiderationsbesidetotals17ComputingAverageandMarginalCostsAveragevariablecost(AVC):variablecostdividedbyquantityofoutputLaboronlyvariablefactorofproductionCalculateAVCbytakingthewagerateanddividingbyAPLAveragecost(AC):totalcostdividedbyquantityofoutputSometimescalledaveragetotalcostMarginalcost(MC):additionalcostattributabletothelastunitofoutputproducedLaboronlyvariablefactorofproductionCalculateMCbytakingthewagerateanddividingbyMPL18ComputingAverageandMarginalCosts19EXHIBIT6.4DerivingtheAverageandMarginalCostCurves20MC&AC21ShapesofCostCurvesVCcurvealwaysincreasingMoreoutputrequiresmorelaborHighercostsTCcurvedeterminedbysumofFCandVCFCconstantHassameshapeasVCcurveMC,AC,andAVCcurvesareU-shaped22EXHIBIT6.5TheGeometryofProductCurvesandCostCurves23CostCurvesRelationsMCrelationshiptoAVCandACMCbelowAVC,AVCfallingMCaboveAVC,AVCrisingMCequalsAVC,AVCatminimumCanreplaceAVCwithAC,sameholdstrueShapesofcostcurvesrelatedtoshapesofproductcurves24ProductionandCostsintheLongRunInlongrun(LR),firmcanadjustemploymentofcapitalandlaborAttemptstoachievetheleastcostmethodofproducingagivenquantityofoutput25IsoquantsGeometryofLRproductionLabelverticalaxiswithK,standsforcapitalLabelhorizontalaxiswithL,whichstandsforlaborFixedperiodoftimeWanttouseleastcostlymethodAvoidtechnologicallyinefficientpointswhichareoutsidetheboundaryGeneralobservationsSlopedownwardFilltheplaneNevercrossConvex26MarginalRateofTechnicalSubstitutionAbsolutevalueofslopeofisoquantMPLdividedbyMPKAmountofcapitalnecessarytoreplaceoneunitoflaborwhilemaintainingaconstantlevelofoutputIfmuchlaborandlittlecapitalemployedtoproduceaunitofoutput,MRTSLKissmallGeometricallyisoquantisconvex27EXHIBIT6.8TheProductionFunction28ChoosingaProductionProcessMinimizingcostimportantpartofmaximizingprofitIsocostallowtokeeptrackofcostsSetofallbasketsofinputsthatcanbeemployedatagivencostSlope:-PL/PKMinimizingcostandmaximizingoutputrequiresfirmchoosetangencypointbetweenanisocostandanisoquantMeansthatMRTS=PL/PKTangenciesliealongcurvecalledthefirm’’sexpansionpath29EXHIBIT6.9CostMinimization30Long-RunCostCurvesInformationneededProductionfunctionorisoquantsInputpricesFirm’’slong-runtotalcostCostofproducingagivenamountofoutputwhenthefirmisabletooperateonitsexpansionpathLong-runaveragecostLong-runtotalcostdividedbyquantityLong-runmarginalcostPartoflong-runtotalcostattributabletothelastunitproduced31EXHIBIT6.11DerivingLong-RunTotalCost32EXHIBIT6.12Long-RunTotal,Marginal,andAverageCosts33ReturnstoScaleWhenallinputquantitiesareincreasedby1%,doesoutputgoupby…morethan1%IncreasingreturnstoscaleOccursatlowlevelsofoutputLong-runaveragecostcurveisdecreasing…exactly1%Constantreturnstoscale“Whatafirmcandoone,itcandotwice””Long-runaveragecostcurveisflat…lessthan1%DecreasingreturnstoscaleOccursatsufficientlyhighlevelsofoutputLong-runaveragecostcurveisincreasing34RelationsbetweentheSRandLRDeriveSRTCfromisoquantsandfactorpricesDeriveLRTCfromisoquantsandfactorpricesSRTCversusLRTCSRTCalwaysatleastasgreatasLRTCMultitudeofshortrunsituat