迈克尔版本微观经济学-第十一章-Chapter11-SM.详解

©2010PearsonEducationCanada©2010PearsonEducationCanadaDecisionTimeFramesThefirmmakesmanydecisionstoachieveitsmainobjective:profitmaximization.Alldecisionscanbeplacedintwotimeframes:TheshortrunThelongrun©2010PearsonEducationCanadaTheShortRunTheshortrunisatimeframeinwhichthequantityofoneormoreresourcesusedinproductionisfixed.Formostfirms,thecapital,calledthefirm’splant,isfixedintheshortrun.Otherresourcesusedbythefirm(suchaslabor,rawmaterials,andenergy)canbechangedintheshortrun.Theshortrunisthereforecharacterizedbylessflexibilityandfreedomtochoosethequantityofallinputs.DecisionTimeFrames©2010PearsonEducationCanadaTheLongRunThelongrunisatimeframeinwhichthequantitiesofallresources—includingtheplantsize—canbevaried.Thelongrunisthereforecharacterizedbymoreflexibilityandfreedomtochoosethequantityofallinputs.DecisionTimeFrames©2010PearsonEducationCanadaDecisionTimeFramesAsunkcostisacostincurredbythefirmandcannotbechanged.Ifafirm’splanthasnoresalevalue,theamountpaidforitisasunkcost.Sunkcostsareirrelevanttoafirm’scurrentdecisions.©2010PearsonEducationCanadaShort-RunTechnologyConstraintTechnologyreferstotherelationshipbetweeninputsandoutput.Toincreaseoutputintheshortrun,afirmmustincreasetheamountofinputsemployed.Threeconceptsdescribetherelationshipbetweenoutputandthequantityoflaboremployed:1.Totalproduct2.Marginalproduct3.Averageproduct©2010PearsonEducationCanadaProductSchedulesTotalproductisthetotaloutputproducedinagivenperiod.Themarginalproductoflabouristhechangeintotalproductthatresultsfromaone-unitincreaseinthequantityoflabouremployed,withallotherinputsremainingthesame.Theaverageproductoflabourisequaltototalproductdividedbythequantityoflabouremployed.Short-RunTechnologyConstraint©2010PearsonEducationCanadaTable11.1showsafirm’sproductschedules.Asthequantityoflabouremployedincreases:Totalproductincreases.Marginalproductincreasesinitiallybuteventuallydecreases.Averageproductincreasesinitiallybuteventuallydecreases.Short-RunTechnologyConstraint©2010PearsonEducationCanadaProductCurvesProductcurvesaregraphsofthethreeproductconceptsthatshowhowtotalproduct,marginalproduct,andaverageproductchangeasthequantityoflabouremployedchanges.Short-RunTechnologyConstraint©2010PearsonEducationCanadaTotalProductCurveFigure11.1showsatotalproductcurve.Thetotalproductcurveshowshowtotalproductchangeswiththequantityoflabouremployed.Short-RunTechnologyConstraint©2010PearsonEducationCanadaThetotalproductcurveissimilartothePPF.Itseparatesattainableoutputlevelsfromunattainableoutputlevelsintheshortrun.Short-RunTechnologyConstraint©2010PearsonEducationCanadaMarginalProductCurveFigure11.2showsthemarginalproductoflabourcurveandhowthemarginalproductcurverelatestothetotalproductcurve.Thefirstworkerhiredproduces4unitsofoutput.Short-RunTechnologyConstraint©2010PearsonEducationCanadaThesecondworkerhiredproduces6unitsofoutputandtotalproductbecomes10units.Thethirdworkerhiredproduces3unitsofoutputandtotalproductbecomes13units.Andsoon.Short-RunTechnologyConstraint©2010PearsonEducationCanadaTheheightofeachbarmeasuresthemarginalproductoflabour.Forexample,whenlabourincreasesfrom2to3,totalproductincreasesfrom10to13,sothemarginalproductofthethirdworkeris3unitsofoutput.Short-RunTechnologyConstraint©2010PearsonEducationCanadaTomakeagraphofthemarginalproductoflabour,wecanstackthebarsinthepreviousgraphsidebyside.Themarginalproductoflabourcurvepassesthroughthemid-pointsofthesebars.Short-RunTechnologyConstraint©2010PearsonEducationCanadaAlmostallproductionprocessesareliketheoneshownhereandhave:IncreasingmarginalreturnsinitiallyDiminishingmarginalreturnseventuallyShort-RunTechnologyConstraint©2010PearsonEducationCanadaIncreasingMarginalReturnsInitiallyWhenthemarginalproductofaworkerexceedsthemarginalproductofthepreviousworker,themarginalproductoflabourincreasesandthefirmexperiencesincreasingmarginalreturns.Short-RunTechnologyConstraint©2010PearsonEducationCanadaDiminishingMarginalReturnsEventuallyWhenthemarginalproductofaworkerislessthanthemarginalproductofthepreviousworker,themarginalproductoflabourdecreases.Thefirmexperiencesdiminishingmarginalreturns.Short-RunTechnologyConstraint©2010PearsonEducationCanadaIncreasingmarginalreturnsarisefromincreasedspecializationanddivisionoflabour.Diminishingmarginalreturnsarisesfromthefactthatemployingadditionalunitsoflabourmeanseachworkerhaslessaccesstocapitalandlessspaceinwhichtowork.Diminishingmarginalreturnsaresopervasivethattheyareelevatedtothestatusofa“law.”Thelawofdiminishingreturnsstatesthat:Asafirmusesmoreofavariableinputwithagivenquantityoffixedinputs,themarginalproductofthevariableinputeventuallydiminishes.Short-RunTechnologyConstraint©2010PearsonEducationCanadaAverageProductCurveFigure11.3showstheaverageproductcurveanditsrelationshipwiththemarginalproductcurve.Short-RunTechnologyConstraint©2010PearsonEducationCanadaWhenmarginalproductexceedsaverageproduct,averageproductincreases.Whenmarginalproductisbelowaverageproduct,averageproductdecreases.Whenmarginalproductequalsaverageproduct,averageproductisatitsmaximum.Sh