院微觀生產(chǎn)函數(shù)成本

ChapterProductionandCost2005ChapterProductionandCost20051北京大學(xué)經(jīng)濟(jì)ChapterFour2北京大學(xué)ChapterFour2北京大學(xué)經(jīng)濟(jì)4.1Production4.2Cost3北京大學(xué)經(jīng)濟(jì)Production3北京大學(xué)經(jīng)濟(jì)ProductionTP,APandIsoquantandDiminishingOptimalInputsintheLongReturnstoScale:ElasticitiesofOutput,ElasticityofOverviewofLastOutlineofToday’sDefinitionofCostOutlineofToday’sDefinitionofCostopportunityExplicitandImplicitFromCostMinimizationtotheCostCostFunctionsIntheShort4北京大學(xué)經(jīng)濟(jì)Zhang:Chapter6,P191-Nicholson:ChapterZhang:Chapter6,P191-Nicholson:Chapter12,P297-5北京大學(xué)經(jīng)濟(jì)ReadingsaboutthepartofthisMeasuringCost:WhichCostsActualexpensesMeasuringCost:WhichCostsActualexpensesplusdepreciationcharges(折舊費(fèi))forcapitalequipmentEconomicCost（經(jīng)濟(jì)成本Costwhichafirmutilizealleconomicresourcesinproduction,includingopportunitycost6北京大學(xué)經(jīng)濟(jì)WhatisOpportunityTheOpportunitycostofusingsomeresourceinaparticularwayisdefinedasthevalueofthatresourceWhatisOpportunityTheOpportunitycostofusingsomeresourceinaparticularwayisdefinedasthevalueofthatresourceinitsnextbestalternativeuse.7北京大學(xué)經(jīng)濟(jì)WhatisOpportunityAnAfirmownsWhatisOpportunityAnAfirmownsitsownbuildingandpaysnorentforofficespaceDoesthismeanthecostofofficespaceisAnswer:8北京大學(xué)經(jīng)濟(jì)SunkCost（沉沒成本ExpenditurethathasSunkCost（沉沒成本ExpenditurethathasbeenmadeandcannotbeShouldnotinfluenceafirm’s9北京大學(xué)經(jīng)濟(jì)ExplicitandImplicitAfirm’scostofproductionExplicitandImplicitAfirm’scostofproductionincludeexplicitcostsandimplicitcosts.Explicitcosts（顯性成本involveamoneyoutlayforfactorsofproductionwhichareboughtfrominputmarkets.Implicitcosts（隱性成本arethoseassociatedwiththeuseofthefirm’sownresourcesandreflectthefactthattheseresourcescouldbeemployedelsewhere.北京大學(xué)經(jīng)濟(jì)EconomicProfitversusAccountingEconomistsmeasureEconomicProfitversusAccountingEconomistsmeasureafirm’seconomic（經(jīng)濟(jì)利潤(rùn)）astotalrevenueminusalltheopportunitycosts(explicitandimplicit).Accountantsmeasuretheaccountingprofit（會(huì)計(jì)利潤(rùn)）asthefirm’stotalrevenueminusonlythefirm’sexplicitcosts.Inotherwords,theyignoretheimplicitcosts.北京大學(xué)經(jīng)濟(jì)EconomicProfitversusAccounting北京大EconomicProfitversusAccounting北京大學(xué)經(jīng)濟(jì)EconomicProfitversusAccountingHowanEconomistViewsaFirmHowanAccountantViewsaFirm北EconomicProfitversusAccountingHowanEconomistViewsaFirmHowanAccountantViewsaFirm北京大學(xué)經(jīng)濟(jì)DefinitionofCostCostshowstherelationbetweentheminimumcosttoDefinitionofCostCostshowstherelationbetweentheminimumcosttoproduceagivenlevelofoutputandoutputlevel,CC(q)北京大學(xué)經(jīng)濟(jì)Short-RunandLong-RunCostIntheShort-RunandLong-RunCostIntheshortrun,somefactorsofproductionarefixed:short-runcostfunctiongivestheminimumcosttoproduceagivenlevelofoutput,onlyadjustingthevariablefactorsofInthelongrunallfactorsarevariable:longruncostfunctiongivestheminimumcosttoproduceagivenlevelofoutput,adjustingallfactorsofproduction.北京大學(xué)經(jīng)濟(jì)FromCostMinimizationtotheCostFromCostMinimizationtotheCostproducesq0atmintotalMincostforeachqTheTotalcostfunction-Withinputpricesw=TheTotalcostfunction北京大學(xué)經(jīng)濟(jì)TheCost-MinimizationConsiderafirmusing2inputsTheCost-MinimizationConsiderafirmusing2inputstomake1Productionfunctionq=Takeoutputlevelq0asGiveninputpricesw1andTotalcostofinputbundle(x1,x2)w1x1+北京大學(xué)經(jīng)濟(jì)TheCost-MinimizationSo,forgivenw1,TheCost-MinimizationSo,forgivenw1,w2andq,firm’scost-minimizationproblemistosolveminw1x1w2S.(1,北京大學(xué)經(jīng)濟(jì)TheCost-MinimizationSolutionx1*(w1,w2,q)andx2*(w1,wTheCost-MinimizationSolutionx1*(w1,w2,q)andx2*(w1,w2,q)areconditionaldemandsforinputs1,Smallestpossibletotalcostforproducingqc(w1,w2,q)x*(w1,w2, wx*(w,, 12北京大學(xué)經(jīng)濟(jì)TheCost-MinimizationProblem:CostminbundlethatwillproduceTheCost-MinimizationProblem:Costminbundlethatwillproducef(x1,x2)北京大學(xué)經(jīng)濟(jì)TheCost-MinimizationProblem:Ataninteriorcost-mininput(a)f(x1*,x2*)=TheCost-MinimizationProblem:Ataninteriorcost-mininput(a)f(x1*,x2*)=(b)slopeofisocost=slopeofat(x*,x*12f(x1,x2)北京大學(xué)經(jīng)濟(jì)Cobb-DouglasExampleofCost,xProductionfunction 12Inputpricesarew1andCobb-DouglasExampleofCost,xProductionfunction 12Inputpricesarew1and1q/q/**(1/3)(x(x122121北京大學(xué)經(jīng)濟(jì)ACobb-DouglasEx.ofCost 2w22x*11From21wNowsubstituteinto(a)toACobb-DouglasEx.ofCost 2w22x*11From21wNowsubstituteinto(a)to2wq(x*1 1w11w22 2/3conditional北京大學(xué)經(jīng)濟(jì)x2q121ACobb-DouglasEx.ofCost2/3w2w1 2q2111w2Firm’sACobb-DouglasEx.ofCost2/3w2w1 2q2111w2Firm’sconditionaldemandforinput22ww2wqq1212ww122北京大學(xué)經(jīng)濟(jì)ACobb-DouglasEx.ofCostSo,costmininputbundleforyunitsof**x(w,w,ACobb-DouglasEx.ofCostSo,costmininputbundleforyunitsof**x(w,w,x(w,w,112212w2/2w1/q211北京大學(xué)經(jīng)濟(jì)ConditionalInputDemandCurves(條件投FixedConditionalInputDemandCurves(條件投Fixedand北京大學(xué)經(jīng)濟(jì)ConditionalInputDemand x2(q22x*(q2*3x(q22x*(q23q32*q1x2ConditionalInputDemand x2(q22x*(q2*3x(q22x*(q23q32*q1x2(qx1111* *1x(q11 1q北京大學(xué)經(jīng)濟(jì)ConditionalInputDemandinput2222x*(q2 x2(q2x*(q2ConditionalInputDemandinput2222x*(q2 x2(q2x*(q232*q1x2(qx111* *1x(q11 1q北京大學(xué)經(jīng)濟(jì)q31Cobb-DouglasExampleofCostSothefirm’slongruntotalcostfunctionc(w1,w2,q)x*Cobb-DouglasExampleofCostSothefirm’slongruntotalcostfunctionc(w1,w2,q)x*(w1,w2,q)x*(w1,w2, 2/32w1/w12qw21wq2w12/1w1/3w2/3q21/3w1/3w2/312122w21/12q4北京大學(xué)經(jīng)CostfunctionintheShortIntheCostfunctionintheShortIntheshortrun,therearesomevariableinputsandsomefixedinputsintheproduction.SocostfunctionCwL(w,r,q)rK(w,r,北京大學(xué)經(jīng)濟(jì)CostFunctionsIntheShortTherefore,theshortruntotalcostofproductionequalsCostFunctionsIntheShortTherefore,theshortruntotalcostofproductionequalsthefixedcost(thecostofthefixedinputs)plusthevariablecost(thecostofthevariableinputs),or…北京大學(xué)經(jīng)濟(jì)CostFunctionsIntheShortFixedCost（固定成本thoseCostFunctionsIntheShortFixedCost（固定成本thosecoststhatdonotvarywiththequantityofoutputproducedVariableCost（變動(dòng)成本thosecoststhatdochangeasthefirmaltersthequantityofoutputproduced.北京大學(xué)經(jīng)濟(jì)FamilyofTotalCostsintheShortFamilyofTotalCostsintheShort北京大學(xué)經(jīng)濟(jì)FromTPLto北京FromTPLto北京大學(xué)經(jīng)濟(jì)CostCurvesfora01234 789CostCurvesfora01234 789北京大學(xué)經(jīng)濟(jì)FamilyofTotal012345FamilyofTotal0123456789Total$Fixed北京大學(xué)Variable$tal-Cost24680Quantityof(glassesftal-Cost24680Quantityof(glassesf學(xué)perTotalFamilyofAverageCostsintheShortFamilyofAverageCostsintheShortAverageFixedCosts(AFC)（平均固定成AverageVariableCosts(AVC)（平均變AverageTotalCosts(ATC)（平均成本ATC=AFC+北京大學(xué)經(jīng)濟(jì)FamilyofAverageFixecosFAF==QuantitFamilyofAverageFixecosFAF==QuantitqVariablcosTCAVC=QuantitqTotacosTATC=Quantitq北京大學(xué)經(jīng)濟(jì)FamilyofAverage0———12345678FamilyofAverage0———123456789北大學(xué)經(jīng)濟(jì)Average-CostandMarginal-Cost02468QuantityofOutputdAverage-CostandMarginal-Cost02468QuantityofOutputdMarginalCost（邊際成本Marginalcost(MC)measurestheamounttotalcostMarginalCost（邊際成本Marginalcost(MC)measurestheamounttotalcostriseswhenthefirmincreasesproductionbyoneunit.北京大學(xué)經(jīng)濟(jì)MarginalMC=(Changeintotalcost)(Changeinquantity)=TCqMarginalMC=(Changeintotalcost)(Changeinquantity)=TCqTCdTCMClimqqdq北京大學(xué)經(jīng)濟(jì)Marginal北京大學(xué)經(jīng)濟(jì)0—162738495Marginal北京大學(xué)經(jīng)濟(jì)0—162738495Average-CostandMarginal-Cost02468QuantityofOutputdAverage-CostandMarginal-Cost02468QuantityofOutputdRelationshipBetweenMarginalCostandAverageRelationshipBetweenMarginalCostandAverageTotalWhenevermarginalcostislessthanaveragetotalcost,averagetotalcostisWhenevermarginalcostisgreaterthanaveragetotalcost,averagetotalcostis北京大學(xué)經(jīng)濟(jì)RelationshipBetweenMarginalCostandAverageTotalCost北京大RelationshipBetweenMarginalCostandAverageTotalCost北京大學(xué)經(jīng)濟(jì)CdAC(q)MC(q)CdAC(q)MC(q)ACdqq北京大學(xué)經(jīng)濟(jì)ProofofRelationshipbetweenMCandTC(qqAC(q),dTC(q)ProofofRelationshipbetweenMCandTC(qqAC(q),dTC(q)qMC(q)1TC(q)dAC(q)dqqqMC(q)TC(q).dAC(q)dAC(q)MC(q)dq北京大學(xué)經(jīng)濟(jì)RelationshipBetweenMarginalCostandAverageVariableCost)RelationshipBetweenMarginalCostandAverageVariableCost)Cq北京大學(xué)經(jīng)濟(jì)ProofofRelationshipbetweenMCandVC(qqAVC(q),dVC(qProofofRelationshipbetweenMCandVC(qqAVC(q),dVC(q)qMC(q)1VC(q)dqqqMC(q)VC(q).dAVC(q)dAVC(q)MC(q)dq北京大學(xué)經(jīng)濟(jì)Summary:Marginal&AverageCostTheshort-runMCcurveintersectstheshort-runSummary:Marginal&AverageCostTheshort-runMCcurveintersectstheshort-runAVCcurvefrombelowattheAVCcurve’sAnd,similarly,theshort-runMCcurveintersectstheshort-runATCcurvefrombelowattheATCcurve’sminimum.北京大學(xué)經(jīng)濟(jì)C北京大學(xué)經(jīng)濟(jì)C北京大學(xué)經(jīng)濟(jì)ThreeImportantPropertiesofCostThreeImportantPropertiesofCostMarginalcosteventuallyriseswiththequantityofoutput.Theaverage-total-costcurveisU-Themarginal-costcurvecrossestheaverage-total-costcurveattheminimumofaveragetotalcost.北京大學(xué)經(jīng)濟(jì)SummaryTCTVCAC、AVCandSummaryTCTVCAC、AVCand北京大學(xué)經(jīng)濟(jì)ProductCurvesandCostHowareProductCurvesandCostHowaretheproductcurvesrelatedtothecostcurves?北京大學(xué)經(jīng)濟(jì)CostintheShortForExample:AssumeCostintheShortForExample:Assumethewagerate(w)isfixedrelativetothenumberofworkershired.Then:北京大學(xué)經(jīng)濟(jì)CostintheShortAVCTVCwLw1wqLqqMCdTVCCostintheShortAVCTVCwLw1wqLqqMCdTVCdwLwdLw11w北京大學(xué)經(jīng)濟(jì)ProductCurvesandCost0北京大學(xué)經(jīng)濟(jì)AverageproductProductCurvesandCost0北京大學(xué)經(jīng)濟(jì)Averageproductandmarginal64isingfallingMC:fallingAVCFallingMPrisingMC:risingProductCurvesandCost963北京大學(xué)經(jīng)濟(jì)0ProductCurvesandCost963北京大學(xué)經(jīng)濟(jì)0AverageproductandmarginalMPandMC、APandMPandMC、APand北京大學(xué)經(jīng)濟(jì)CostFunctionsIntheShortRun:AnalgebraInourexample,theshort-runcostCostFunc