管理经济学 chp4

ManagerialEconomics&BusinessStrategyChapter4TheTheoryofIndividualBehaviorMcGraw-Hill/IrwinMichaelR.Baye,ManagerialEconomicsandBusinessStrategyCopyright©2008bytheMcGraw-HillCompanies,Inc.Allrightsreserved.OverviewI.ConsumerBehaviorIndifferenceCurveAnalysisConsumerPreferenceOrderingII.ConstraintsTheBudgetConstraintChangesinIncomeChangesinPricesIII.ConsumerEquilibriumIV.IndifferenceCurveAnalysis&DemandCurvesIndividualDemandMarketDemand4-2ConsumerBehavior•ConsumerOpportunitiesThepossiblegoodsandservicesconsumercanaffordtoconsume.•ConsumerPreferencesThegoodsandservicesconsumersactuallyconsume.•Giventhechoicebetween2bundlesofgoodsaconsumereitherPrefersbundleAtobundleB:AB.PrefersbundleBtobundleA:AB.Isindifferentbetweenthetwo:AB.4-3ConsumerPreferenceOrderingProperties•Completeness•MoreisBetter•DiminishingMarginalRateofSubstitution•Transitivity4-4CompletePreferences•CompletenessPropertyConsumeriscapableofexpressingpreferences(orindifference)betweenallpossiblebundles.(“Idon’tknow”isNOTanoption!)•IftheonlybundlesavailabletoaconsumerareA,B,andC,thentheconsumer–isindifferentbetweenAandC(theyareonthesameindifferencecurve).–willpreferBtoA.–willpreferBtoC.I.II.III.GoodYGoodXACB4-5MoreIsBetter!•MoreIsBetterPropertyBundlesthathaveatleastasmuchofeverygoodandmoreofsomegoodarepreferredtootherbundles.•BundleBispreferredtoAsinceBcontainsatleastasmuchofgoodYandstrictlymoreofgoodX.•BundleBisalsopreferredtoCsinceBcontainsatleastasmuchofgoodXandstrictlymoreofgoodY.•Moregenerally,allbundlesonICIIIarepreferredtobundlesonICIIorICI.AndallbundlesonICIIarepreferredtoICI.I.II.III.GoodYGoodXACB133.3310034-6DiminishingMarginalRateofSubstitution•MarginalRateofSubstitutionTheamountofgoodYtheconsumeriswillingtogiveuptomaintainthesamesatisfactionleveldecreasesasmoreofgoodXisacquired.Therateatwhichaconsumeriswillingtosubstituteonegoodforanotherandmaintainthesamesatisfactionlevel.•TogofromconsumptionbundleAtoBtheconsumermustgiveup50unitsofYtogetoneadditionalunitofX.•TogofromconsumptionbundleBtoCtheconsumermustgiveup16.67unitsofYtogetoneadditionalunitofX.•TogofromconsumptionbundleCtoDtheconsumermustgiveuponly8.33unitsofYtogetoneadditionalunitofX.I.II.III.GoodYGoodX13421005033.3325ABCD4-7ConsistentBundleOrderings•TransitivityPropertyForthethreebundlesA,B,andC,thetransitivitypropertyimpliesthatifCBandBA,thenCA.Transitivepreferencesalongwiththemore-is-betterpropertyimplythat•indifferencecurveswillnotintersect.•theconsumerwillnotgetcaughtinaperpetualcycleofindecision.I.II.III.GoodYGoodX21100550775ABC4-8IndifferenceCurveAnalysisIndifferenceCurveAcurvethatdefinesthecombinationsof2ormoregoodsthatgiveaconsumerthesamelevelofsatisfaction.MarginalRateofSubstitutionTherateatwhichaconsumeriswillingtosubstituteonegoodforanotherandmaintainthesamesatisfactionlevel.I.II.III.GoodYGoodX4-9TheBudgetConstraint•OpportunitySetThesetofconsumptionbundlesthatareaffordable.•PxX+PyYM.•BudgetLineThebundlesofgoodsthatexhaustaconsumersincome.•PxX+PyY=M.•MarketRateofSubstitutionTheslopeofthebudgetline•-Px/PyYXTheOpportunitySetBudgetLineY=M/PY–(PX/PY)XM/PYM/PX4-10ChangesintheBudgetLine•ChangesinIncomeIncreasesleadtoaparallel,outwardshiftinthebudgetline(M1M0).Decreasesleadtoaparallel,downwardshift(M2M0).•ChangesinPriceAdecreasesinthepriceofgoodXrotatesthebudgetlinecounter-clockwise(PX0PX1).Anincreasesrotatesthebudgetlineclockwise(notshown).XYXYNewBudgetLineforapricedecrease.M0/PYM0/PXM2/PYM2/PXM1/PYM1/PXM0/PYM0/PX0M0/PX14-11ConsumerEquilibrium•Theequilibriumconsumptionbundleistheaffordablebundlethatyieldsthehighestlevelofsatisfaction.ConsumerequilibriumoccursatapointwhereMRS=PX/PY.Equivalently,theslopeoftheindifferencecurveequalsthebudgetline.I.II.III.XYConsumerEquilibriumM/PYM/PX4-12PriceChangesandConsumerEquilibrium•SubstituteGoodsAnincrease(decrease)inthepriceofgoodXleadstoanincrease(decrease)intheconsumptionofgoodY.•Examples:–CokeandPepsi.–VerizonWirelessorAT&T.•ComplementaryGoodsAnincrease(decrease)inthepriceofgoodXleadstoadecrease(increase)intheconsumptionofgoodY.•Examples:–DVDandDVDplayers.–ComputerCPUsandmonitors.4-13SubstituteGoodsWhenthepriceofgoodXfallsandtheconsumptionofYfalls,thenXandYaresubstitutegoods.(PX1PX2)Artichokes(Y)BrusselSprouts(X)III0Y2Y1X1X2ABM/PX1M/PX2M/PY1ComplementaryGoodsWhenthepriceofgoodXfallsandtheconsumptionofYrises,thenXandYarecomplementarygoods.(PX1PX2)Pretzels(Y)Beer(X)III0Y2Y1X1X2ABM/PX1M/PX2M/PY14-15IncomeChangesandConsumerEquilibrium•NormalGoodsGoodXisanormalgoodifanincrease(decrease)inincomeleadstoanincrease(decrease)initsconsumption.•InferiorGoodsGoodXisaninferiorgoodifanincrease(decrease)inincomeleadstoadecrease(increase)initsconsumption.4-16NormalGoodsAnincreaseinincomeincreasestheconsumptionofnormalgoods.(M0M1).YIII0ABXM0/YM0/XM1/YM1/XX0Y0X1Y14-17DecomposingtheIncomeandSubstitutionEffectsInitially,bundleAisconsumed.AdecreaseinthepriceofgoodXexpandstheconsumer’sopportunityset.Thesubstitutioneffect(SE)causestheconsumertomovefrombundleAtoB.Ahigher“realincome”allowstheconsumertoachieveahigherindiff