巴罗宏观经济学：现代观点第4章.ppt

MacroeconomicsChapter4,1,WorkingwiththeSolowGrowthModel,Chapter4,MacroeconomicsChapter4,2,KeyEquationsSolowGrowthModel,k/k=s(y/k)snkiscapitalperworkeryisrealgrossdomesticproduct(realGDP)perworkery/kistheaverageproductofcapitalsisthesavingrateisthedepreciationratenisthepopulationgrowthrate.,MacroeconomicsChapter4,3,SolowGrowthModelSteadyStates(y*/k*)=s+n,Weassumedthateverythingontheright-handsidewasconstantexceptfory/k.Inthetransitiontothesteadystate,theriseinkledtoafalliny/kand,hence,toafallink/k.Inthesteadystate,kwasconstantand,therefore,y/kwasconstant.Hence,k/kwasconstantandequaltozero.,MacroeconomicsChapter4,4,SolowGrowthModelChangeinsavingsrate(s),MacroeconomicsChapter4,5,SolowGrowthModelChangeinsavingsrate(s),Intheshortrun,anincreaseinthesavingrateraisesthegrowthrateofcapitalperworker.Thisgrowthrateremainshigherduringthetransitiontothesteadystate.,MacroeconomicsChapter4,6,SolowGrowthModelChangeinsavingsrate(s),Inthelongrun,thegrowthrateofcapitalperworkeristhesamezeroforanysavingrate.Inthislong-runorsteady-statesituation,ahighersavingrateleadstohighersteadystatecapitalperworker,k,nottoachangeinthegrowthrate(whichremainsatzero).Af(k*)/k*=+n/s,MacroeconomicsChapter4,7,SolowGrowthModeltheeffectofsonconsumptions,Intheshortrun,consumptiondecreasesandkarises.c*=y*-k*-s(y*-k*)=y*-k*-nk*c*=y*-(+n)k*=(MPK-n)k*Inthelongrun,whethertheconsumptioninthesteadystateincreasesdependsonMPK.“GoldenRule”,MacroeconomicsChapter4,8,SolowGrowthModelChangeintechnologylevel(A),MacroeconomicsChapter4,9,SolowGrowthModelChangeintechnologylevel(A),Intheshortrun,anincreaseinthetechnologylevel,A,raisesthegrowthratesofcapitalandrealGDPperworker.Thesegrowthratesremainhigherduringthetransitiontothesteadystate.,MacroeconomicsChapter4,10,SolowGrowthModelChangeintechnologylevel(A),Inthelongrun,thegrowthratesofcapitalandrealGDPperworkerarethesamezeroforanytechnologylevel.Inthislong-runorsteadystatesituation,ahighertechnologylevelleadstohighersteady-statecapitalandrealGDPperworker,kandy,nottochangesinthegrowthrates(whichremainatzero).Af(k*)/k*=+n/s,MacroeconomicsChapter4,11,SolowGrowthModelChangeinthelaborinput,MacroeconomicsChapter4,12,SolowGrowthModelChangeinthelaborinput,Intheshortrun,anincreaseinlaborinput,L(0),raisesthegrowthratesofcapitalandrealGDPperworker.Thesegrowthratesremainhigherduringthetransitiontothesteadystate.,MacroeconomicsChapter4,13,SolowGrowthModelChangeinthelaborinput,Inthelongrun,thegrowthratesofcapitalandrealGDPperworkerarethesamezeroforanyleveloflaborinput,L(0).Thesteady-statecapitalandrealGDPperworker,kandy,arethesameforanyL.InthelongrunaneconomywithtwiceasmuchlaborinputhastwiceasmuchcapitalandrealGDP.,MacroeconomicsChapter4,14,SolowGrowthModelChangeinpopulationgrowthrate,MacroeconomicsChapter4,15,SolowGrowthModelChangeinpopulationgrowthrate,MacroeconomicsChapter4,16,SolowGrowthModelChangeinpopulationgrowthrate,Intheshortrun,ahighernlowersk/kandy/y.Thesegrowthratesremainlowerduringthetransitiontothesteadystate.,MacroeconomicsChapter4,17,SolowGrowthModelChangeinpopulationgrowthrate,Inthesteadystate,k/kandy/yarezeroforanyn.Ahighernleadstolowersteady-statecapitalandrealGDPperworker,kandy,nottochangesinthegrowthrates,k/kandy/y(whichremainatzero).Achangeinndoesaffectthesteady-stategrowthratesofthelevelsofcapitalandrealGDP,K/KandY/Y.,MacroeconomicsChapter4,18,SolowGrowthModelSumup,k*=k*s,A,n,L(0)(+)(+)()()(0),MacroeconomicsChapter4,19,SolowGrowthModelConvergence,Oneofthemostimportantquestionsabouteconomicgrowthis:whetherpoorcountriestendtoconvergeorcatchuptorichcountries.,MacroeconomicsChapter4,20,SolowGrowthModelConvergence,MacroeconomicsChapter4,21,SolowGrowthModelConvergence,Economy1startswithlowercapitalperworkerthaneconomy2k(0)1islessthank(0)2.Economy1growsfasterinitiallybecausetheverticaldistancebetweenthes(y/k)curveandthes+nlineisgreateratk(0)1thanatk(0)2.,MacroeconomicsChapter4,22,SolowGrowthModelConvergence,Thatis,thedistancemarkedbytheredarrowsisgreaterthanthatmarkedbythebluearrows.Therefore,capitalperworkerineconomy1,k1,convergesovertimetowardthatineconomy2,k2.,MacroeconomicsChapter4,23,SolowGrowthModelConvergence,MacroeconomicsChapter4,24,SolowGrowthModelConvergence,Economy1startsatcapitalperworkerk(0)1andeconomy2startsatk(0)2,wherek(0)1islessthank(0)2.Thetwoeconomieshavethesamesteady-statecapitalperworker,k*,shownbythedashedblueline.Ineacheconomy,krisesovertimetowardk*.However,kgrowsfasterineconomy1becausek(0)1islessthank(0)2.Therefore,k1convergesovertimetowardk2.,MacroeconomicsChapter4,25,SolowGrowthModelConvergence,y=Af(k)andy/y=(k/k)k/kwashigherinitiallyineconomy1thanineconomy2.Therefore,y/yisalsohigherinitiallyineconomy1.Hence,economy1srealGDPperworker,y,convergesovertimetowardeconomy2srealGDPperworker.,MacroeconomicsChapter4,26,SolowGrowthModelConvergence,TheSolowmodelsaysthatapooreconomywithlowcapitalandrealGDPperworkergrowsfasterthanarichone.Thereasonisthediminishingaverageproductofcapital,y/k.TheSolowmodelpredictsthatpoorereconomiestendtoconvergeovertimetowardricheronesintermsofthelevelsofcapitalandrealGDPperworker.,MacroeconomicsChapter4,27,SolowGrowthModelConvergence,MacroeconomicsChapter4,28,SolowGrowthModelConvergence,MacroeconomicsChapter4,29,SolowGrowthModelConvergence,MacroeconomicsChapter4,30,SolowGrowthModelConvergence,MacroeconomicsChapter4,31,SolowGrowthModelConvergence,Economy1startswithlowercapitalperworkerthaneconomy2k(0)1k(0)2.Assumethateconomy1alsohasalowersavingrate;s1s2.Thetwoeconomieshavethesametechnologylevels,A,andpopulationgrowthrates,n.Therefore,k*1islessthank*2.Itisuncertainwhicheconomygrowsfasterinitially.Theverticaldistancemarkedwiththebluearrowsmaybelargerorsmallerthantheonemarkedwiththeredarrows.,MacroeconomicsChapter4,32,SolowGrowthModelConvergence,MacroeconomicsChapter4,33,SolowGrowthModelConvergence,Economy1startswithlowercapitalperworkerthaneconomy2k(0)1n2.Therefore,k*1islessthank*2.Itisagainuncertainwhicheconomygrowsfasterinitially.Theverticaldistancemarkedwiththebluearrowsmaybelargerorsmallerthantheonemarkedwiththeredarrows.,MacroeconomicsChapter4,34,SolowGrowthModelConvergence,MacroeconomicsChapter4,35,SolowGrowthModelConvergence,Economy1hasalowerstartingcapitalperworkerk(0)1k(0)2andalsohasalowersteady-statecapitalperworkerk*1(thedashedbrownline)islessthank*2(thedashedblueline).Eachcapitalperworkerconvergesovertimetowarditsownsteady-statevalue:k1(theredcurve)towardk*1,Andk2(thegreencurve)towardk*2.However,sincek*1islessthank*2,k1doesnotconvergetowardk2.,MacroeconomicsChapter4,