ChExchange微觀范里安上海交通大學趙旭實用

會計學1ChExchange微觀范里安上海交通大學趙旭實用ExchangeEdgeworthandBowleydevisedadiagram,calledanEdgeworthbox,toshowallpossibleallocationsoftheavailablequantitiesofgoods1and2betweenthetwoconsumers.第1頁/共106頁StartinganEdgeworthBox第2頁/共106頁StartinganEdgeworthBoxWidth=第3頁/共106頁StartinganEdgeworthBoxWidth=Height=第4頁/共106頁StartinganEdgeworthBoxWidth=Height=Thedimensionsof

theboxarethe

quantitiesavailable

ofthegoods.第5頁/共106頁FeasibleAllocationsWhatallocationsofthe8unitsofgood1andthe6unitsofgood2arefeasible?HowcanallofthefeasibleallocationsbedepictedbytheEdgeworthboxdiagram?第6頁/共106頁FeasibleAllocationsWhatallocationsofthe8unitsofgood1andthe6unitsofgood2arefeasible?HowcanallofthefeasibleallocationsbedepictedbytheEdgeworthboxdiagram?Onefeasibleallocationisthebefore-tradeallocation;i.e.theendowmentallocation.第7頁/共106頁Width=Height=Theendowment

allocationisandTheEndowmentAllocation第8頁/共106頁Width=Height=TheEndowmentAllocation第9頁/共106頁OAOB68TheEndowmentAllocation第10頁/共106頁OAOB6846TheEndowmentAllocation第11頁/共106頁OAOB684622TheEndowmentAllocation第12頁/共106頁OAOB684622The

endowment

allocationTheEndowmentAllocation第13頁/共106頁Moregenerally,…TheEndowmentAllocation第14頁/共106頁TheEndowmentAllocationOAOBThe

endowment

allocation第15頁/共106頁OtherFeasibleAllocationsdenotesanallocationtoconsumerA.denotesanallocationtoconsumerB.Anallocationisfeasibleifandonlyifand第16頁/共106頁FeasibleReallocationsOAOB第17頁/共106頁FeasibleReallocationsOAOB第18頁/共106頁FeasibleReallocationsAllpointsinthebox,includingtheboundary,representfeasibleallocationsofthecombinedendowments.第19頁/共106頁FeasibleReallocationsAllpointsinthebox,includingtheboundary,representfeasibleallocationsofthecombinedendowments.Whichallocationswillbeblockedbyoneorbothconsumers?Whichallocationsmakebothconsumersbetteroff?第20頁/共106頁AddingPreferencestotheBoxOAForconsumerA.第21頁/共106頁AddingPreferencestotheBoxMorepreferredForconsumerA.OA第22頁/共106頁AddingPreferencestotheBoxForconsumerB.OB第23頁/共106頁AddingPreferencestotheBoxMorepreferredForconsumerB.OB第24頁/共106頁AddingPreferencestotheBoxMorepreferredForconsumerB.OB第25頁/共106頁AddingPreferencestotheBoxOAForconsumerA.第26頁/共106頁AddingPreferencestotheBoxOAOB第27頁/共106頁Edgeworth’sBoxOAOB第28頁/共106頁Pareto-ImprovementAnallocationoftheendowmentthatimprovesthewelfareofaconsumerwithoutreducingthewelfareofanotherisaPareto-improvingallocation.WherearethePareto-improvingallocations?第29頁/共106頁Edgeworth’sBoxOAOB第30頁/共106頁Pareto-ImprovementsOAOBThesetofPareto-

improvingallocations第31頁/共106頁Pareto-ImprovementsSinceeachconsumercanrefusetotrade,theonlypossibleoutcomesfromexchangearePareto-improvingallocations.ButwhichparticularPareto-improvingallocationwillbetheoutcomeoftrade?第32頁/共106頁Pareto-ImprovementsOAOBThesetofPareto-

improvingreallocations第33頁/共106頁Pareto-Improvements第34頁/共106頁Pareto-Improvements第35頁/共106頁Pareto-ImprovementsTrade

improvesboth

A’sandB’swelfares.

ThisisaPareto-improvement

overtheendowmentallocation.第36頁/共106頁Pareto-ImprovementsNewmutualgains-to-traderegion

isthesetofallfurtherPareto-

improving

reallocations.

Trade

improvesboth

A’sandB’swelfares.

ThisisaPareto-improvement

overtheendowmentallocation.第37頁/共106頁Pareto-ImprovementsFurthertradecannotimprove

bothAandB’s

welfares.第38頁/共106頁Pareto-OptimalityBetterfor

consumerBBetterfor

consumerA第39頁/共106頁Pareto-OptimalityAisstrictlybetteroff

butBisstrictlyworse

off第40頁/共106頁Pareto-OptimalityAisstrictlybetteroff

butBisstrictlyworse

offBisstrictlybetter

offbutAisstrictly

worseoff第41頁/共106頁Pareto-OptimalityAisstrictlybetteroff

butBisstrictlyworse

offBisstrictlybetter

offbutAisstrictly

worseoffBothAand

Bareworse

off第42頁/共106頁Pareto-OptimalityAisstrictlybetteroff

butBisstrictlyworse

offBisstrictlybetter

offbutAisstrictly

worseoffBothA

andBare

worse

offBothAand

Bareworse

off第43頁/共106頁Pareto-OptimalityTheallocationis

Pareto-optimalsincethe

onlywayoneconsumer’swelfarecanbeincreasedisto

decreasethewelfareoftheother

consumer.第44頁/共106頁Pareto-OptimalityTheallocationis

Pareto-optimalsincethe

onlywayoneconsumer’swelfarecanbeincreasedisto

decreasethewelfareoftheother

consumer.Anallocationwhereconvex

indifferencecurvesare“only

justback-to-back”is

Pareto-optimal.第45頁/共106頁Pareto-OptimalityWhereareallofthePareto-optimalallocationsoftheendowment?第46頁/共106頁Pareto-OptimalityOAOB第47頁/共106頁Pareto-OptimalityOAOBAlltheallocationsmarkedby

aarePareto-optimal.第48頁/共106頁Pareto-OptimalityThecontractcurveisthesetofallPareto-optimalallocations.第49頁/共106頁Pareto-OptimalityOAOBAlltheallocationsmarkedby

aarePareto-optimal.Thecontractcurve第50頁/共106頁Pareto-OptimalityButtowhichofthemanyallocationsonthecontractcurvewillconsumerstrade?Thatdependsuponhowtradeisconducted.Inperfectlycompetitivemarkets?Byone-on-onebargaining?第51頁/共106頁TheCoreOAOBThesetofPareto-

improvingreallocations第52頁/共106頁TheCoreOAOB第53頁/共106頁TheCoreOAOBPareto-optimaltradesblocked

byBPareto-optimaltradesblocked

byA第54頁/共106頁TheCoreOAOBPareto-optimaltradesnotblocked

byAorB第55頁/共106頁TheCoreOAOBPareto-optimaltradesnotblocked

byAorBarethecore.第56頁/共106頁TheCoreThecoreisthesetofallPareto-optimalallocationsthatarewelfare-improvingforbothconsumersrelativetotheirownendowments.Rationaltradeshouldachieveacoreallocation.第57頁/共106頁TheCoreButwhichcoreallocation?Again,thatdependsuponthemannerinwhichtradeisconducted.第58頁/共106頁TradeinCompetitiveMarketsConsidertradeinperfectlycompetitivemarkets.Eachconsumerisaprice-takertryingtomaximizeherownutilitygivenp1,p2andherownendowment.Thatis,...第59頁/共106頁TradeinCompetitiveMarketsOAForconsumerA.第60頁/共106頁TradeinCompetitiveMarketsSogivenp1andp2,consumerA’snetdemandsforcommodities1and2areand第61頁/共106頁TradeinCompetitiveMarketsAnd,similarly,forconsumerB…第62頁/共106頁TradeinCompetitiveMarketsForconsumerB.OB第63頁/共106頁TradeinCompetitiveMarketsSogivenp1andp2,consumerB’snetdemandsforcommodities1and2areand第64頁/共106頁TradeinCompetitiveMarketsAgeneralequilibriumoccurswhenpricesp1andp2causeboththemarketsforcommodities1and2toclear;i.e.and第65頁/共106頁TradeinCompetitiveMarketsOAOB第66頁/共106頁TradeinCompetitiveMarketsOAOBCanthisPOallocationbeachieved?第67頁/共106頁TradeinCompetitiveMarketsOAOBBudgetconstraintforconsumerA第68頁/共106頁TradeinCompetitiveMarketsOAOBBudgetconstraintforconsumerA第69頁/共106頁TradeinCompetitiveMarketsOAOBBudgetconstraintforconsumerB第70頁/共106頁TradeinCompetitiveMarketsOAOBBudgetconstraintforconsumerB第71頁/共106頁TradeinCompetitiveMarketsOAOBBut第72頁/共106頁TradeinCompetitiveMarketsOAOBand第73頁/共106頁TradeinCompetitiveMarketsSoatthegivenpricesp1andp2thereisanexcesssupplyofcommodity1excessdemandforcommodity2.Neithermarketclearssothepricesp1andp2donotcauseageneralequilibrium.第74頁/共106頁TradeinCompetitiveMarketsOAOBSothisPOallocationcannotbeachievedbycompetitivetrading.第75頁/共106頁TradeinCompetitiveMarketsOAOBWhichPOallocationscanbe

achievedbycompetitivetrading?第76頁/共106頁TradeinCompetitiveMarketsSincethereisanexcessdemandforcommodity2,p2willrise.Sincethereisanexcesssupplyofcommodity1,p1willfall.Theslopeofthebudgetconstraintsis-p1/p2sothebudgetconstraintswillpivotabouttheendowmentpointandbecomelesssteep.第77頁/共106頁TradeinCompetitiveMarketsOAOBWhichPOallocationscanbe

achievedbycompetitivetrading?第78頁/共106頁TradeinCompetitiveMarketsOAOBWhichPOallocationscanbe

achievedbycompetitivetrading?第79頁/共106頁TradeinCompetitiveMarketsOAOBWhichPOallocationscanbe

achievedbycompetitivetrading?第80頁/共106頁TradeinCompetitiveMarketsOAOBBudgetconstraintforconsumerA第81頁/共106頁TradeinCompetitiveMarketsOAOBBudgetconstraintforconsumerA第82頁/共106頁TradeinCompetitiveMarketsOAOBBudgetconstraintforconsumerB第83頁/共106頁TradeinCompetitiveMarketsOAOBBudgetconstraintforconsumerB第84頁/共106頁TradeinCompetitiveMarketsOAOBSo第85頁/共106頁TradeinCompetitiveMarketsOAOBand第86頁/共106頁TradeinCompetitiveMarketsAtthenewpricesp1andp2bothmarketsclear;thereisageneralequilibrium.TradingincompetitivemarketsachievesaparticularPareto-optimalallocationoftheendowments.ThisisanexampleoftheFirstFundamentalTheoremofWelfareEconomics.第87頁/共106頁FirstFundamentalTheoremofWelfareEconomicsGiventhatconsumers’preferencesarewell-behaved,tradinginperfectlycompetitivemarketsimplementsaPareto-optimalallocationoftheeconomy’sendowment.第88頁/共106頁SecondFundamentalTheoremofWelfareEconomicsTheFirstTheoremisfollowedbyasecondthatstatesthatanyPareto-optimalallocation(i.e.anypointonthecontractcurve)canbeachievedbytradingincompetitivemarketsprovidedthatendowmentsarefirstappropriatelyrearrangedamongsttheconsumers.第89頁/共106頁Giventhatconsumers’preferencesarewell-behaved,foranyPareto-optimalallocationtherearepricesandanallocationofthetotalendowmentthatmakesthePareto-optimalallocationimplementablebytradingincompetitivemarkets.SecondFundamentalTheoremofWelfareEconomics第90頁/共106頁SecondFundamentalTheoremOAOBThecontractcurve第91頁/共106頁SecondFundamentalTheoremOAOB第92頁/共106頁SecondFundamentalTheoremOAOBImplementedbycompetitivetradingfromtheendowmentw.第93頁/共106頁SecondFundamentalTheoremOAOBCanthisallocationbeimplemented

bycompetitivetradingfromw?第94頁/共106頁SecondFundamentalTheoremOAOBCanthisallocationbeimplemented

bycompetitivetradingfromw?No.第95頁/共106頁SecondFundamentalTheoremOAOBButthisallocationisimplemented

bycompetitivetradingfromq.第96頁/共106頁Walras’LawWalras’Lawisanidentity;i.e