消费收入关系

TheHousehold-ConsumptionSectorChapter05Copyright©2011byTheMcGraw-HillCompanies,Inc.Allrightsreserved.McGraw-Hill/Irwin5-2LearningObjectivesAfterthischapter,youshouldbeableto:1.Defineandcomputetheaveragepropensitytoconsumeandtheaveragepropensitytosave.2.Defineandcomputethemarginalpropensitytoconsumeandthemarginalpropensitytosave.3.Explaintheconsumptionfunction.4.Explainthesavingsfunction.5.Calculateautonomousandinducedconsumption.6.Listanddiscussthedeterminantsofconsumption.7.Interpretandassessthepermanentincomehypothesis.8.Explainwhywespendsomuchandsavesolittle.5-3GDPandBigNumbersGrossDomesticProduct(GDP)isthenation’sexpenditureonallfinalgoodsandservicesproducedduringtheyearatmarketprices.Consumption,investment,andgovernmentspendingarethethreemainsectorsofGDP.GDPwas$14.2trillionfor2009and$15.6tto2012.•Thiscanbewrittenas$15,600,000,000,000$15,600billion$15.6trillion•Consumptionbyhouseholdswas$10.089trillionin2009andabout$11.0trillionin2012.5-4FourPartsofGDPConsumption------------C(thischapter)•Consumptionincludesspendingonconsumergoodsandservices.Investment----------------I(Chapter6)•Investmentincludesbusinessinvestmentsincapitalandinventories,aswellasresidentialinvestmentbyhouseholds.Government--------------G(Chapter7)•Governmentspendingongoodsandservices.Netexports---------------Xn(Chapter8)•Exportsminusimports.5-5ConsumptionCisthelargestsectorofGDP.•Cnowaccountsfor7outofevery10dollarsspentonfinalgoodsandservices.Americansspendvirtuallyalloftheirincomeaftertaxes,althoughsavingshaveincreasedslightlysince2007.•Consumersspend67.7percentoftheirdisposableincomeonservicessuchasmedicalcare,gasoline,eatingout,videorentals,lifeinsurance,andlegalfees.•Therestisspentondurablegoods,suchastelevisionsetsandfurniture,oronnondurablegoods,suchasfoodandgasoline.5-6ConsumptionFunctionAfunctionspecifiesarelationshipbetweentwovariables.•Cvarieswiththelevelofafter-taxincome.•JohnMaynardKeynesnotedthatconsumptionwasastablecomponentofincome.Theconsumptionfunctionstatesthat•Asincomerises,consumption(C)rises,butnotasquickly.•Therefore,consumptionvarieswithdisposableincome(DI).DIincreases...Cincreasesbutbyasmalleramount.DIdecreases...Cdecreasesbutbyasmalleramount.Wewilllookatthemathematicalrelationshipsbehindthisfunctionandthengraphit.5-7Example:ConsumptionandDisposableIncome(inbillionsofdollars)DisposableIncomeConsumption1,0001,4002,0002,2003,0003,0004,0003,8005,0004,600NotethatCDIatverylowincomelevels.5-8ConsumptionandDisposableIncomeDisposableIncomeConsumption1,0001,4002,0002,2003,0003,0004,0003,8005,0004,600+1000+800+1000+800+1000+800+1000+800EachtimeDIincreasesby$1,000,Cincreasesby$800.+1000+8005-9SavingSavingisdefinedasNOTspending.•DI–C=S•Themorewespend,thelesswesave.Alowsavingsrateleadstoalowproductivitygrowthrate.•Withoutsavings($)toinvestinNEWplantandequipment,wecannotraiseourproductivityfastenough!5-10Source:EconomicReportofthePresident,2010,SurveyofCurrentBusiness,March2010SavingasaPercentageofDisposableIncome5-11HouseholdSavingasaPercentageofDisposableIncomein2009TheU.S.savingrateislowcomparedwithotherdevelopedeconomies.Source:OECD5-12QuestionsforThoughtandDiscussionAmericansspendmoreonservicesthanondurableandnon-durablegoods.Giveanexampleofeachcategoryfromyourownspendinghabits.Howisitpossibletoconsumemorethanyourincome?Ifacountryhasanegativesavingrate,doesthatmeanthatnobodyinthecountryissaving?5-13FourConceptsAveragePropensitytoConsume:thepercentageofdisposableincomethatisspentAveragePropensitytoSave:thepercentageofincomethatissaved•APC+APS=100%ofDIor1.00indecimalformMarginalPropensitytoConsume:thepercentageofanincreaseindisposableincomethatisspent•changeinCdividedbychangeinDIMarginalPropensitytoSave:thepercentageofanincreaseindisposableincomethatissaved•changeinSdividedbychangeinDI•MPC+MPS=1.00indecimalform5-14AveragePropensitytoConsume(APC)(ThePercentofDISpent)APC=ConsumptionDisposableIncome5-15APCvaluesandtheirmeaningTheAPCmay=1signifyingalldisposableincomeisconsumed.TheAPCmaybe1signifyingyouareconsumingmorethanyourdisposableincomebydippingintoyoursavings.TheAPCmaybe1indicatingyou’reasavingaportionofyourdisposableincome.5-16SampleAPCProblemDisposableIncomeConsumptionSaving$40,000$30,000$10,000APC====.75C300003DI4000045-17DisposableIncomeConsumptionSaving$40,000$30,000SampleAPCProblem5-18SampleAPCProblemDisposableIncomeConsumptionSaving$40,000$30,000$10,000APC====.75C300003DI400004APS====.25S100001DI4000045-19SampleAPCProblemDisposableIncomeConsumptionSaving$40,000$30,000$10,000APC====.75C300003DI400004APS====.25S100001DI400004+1.05-20APCsGreaterThanOneDisposableIncomeConsumptionSaving$10,000$12,0005-21APCsGreaterThanOneDisposableIncomeConsumptionSaving$10,000$12,000–2000Whereisthisgoingtocomefrom?5-22APCsGreaterThanOneDisposableIncomeConsumptionSaving$10,000$12,000–2000APC====1.2C$12,00012DI$10,000105-23APCsGreaterThanOneDisposableIncomeConsumptionSaving$10,000$12,000–2000APC====1.2C$12,00012DI$10,00010APS===–0.2S-$2,000-2DI$10,000105-24APCsGreaterThanOneDisposableIncomeConsumptionSav