克鲁格曼国际经济学课后答案英语版.doc 56页

'CHAPTER2LABORPRODUCTIVITYANDCOMPARATIVEADVANTAGE:THERICARDIANMODELANSWERSTOTEXTBOOKPROBLEMS1.a.Theproductionpossibilitycurveisastraightlinethatinterceptstheappleaxisat400(1200/3)andthebananaaxisat600(1200/2).b.Theopportunitycostofapplesintermsofbananasis3/2.Ittakesthreeunitsoflabortoharvestanapplebutonlytwounitsoflabortoharvestabanana.Ifoneforegoesharvestinganapple,thisfreesupthreeunitsoflabor.These3unitsoflaborcouldthenbeusedtoharvest1.5bananas.c.Labormobilityensuresacommonwageineachsectorandcompetitionensuresthepriceofgoodsequalstheircostofproduction.Thus,therelativepriceequalstherelativecosts,whichequalsthewagetimestheunitlaborrequirementforapplesdividedbythewagetimestheunitlaborrequirementforbananas.Sincewagesareequalacrosssectors,thepriceratioequalstheratiooftheunitlaborrequirement,whichis3applesper2bananas.2.a.Theproductionpossibilitycurveislinear,withtheinterceptontheappleaxisequalto160(800/5)andtheinterceptonthebananaaxisequalto800(800/1).b.Theworldrelativesupplycurveisconstructedbydeterminingthesupplyofapplesrelativetothesupplyofbananasateachrelativeprice.Thelowestrelativepriceatwhichapplesareharvestedis3applesper2bananas.Therelativesupplycurveisflatatthisprice.Themaximumnumberofapplessuppliedatthepriceof3/2is400suppliedbyHomewhile,atthisprice,Foreignharvests800bananasandnoapples,givingamaximumrelativesupplyatthispriceof1/2.Thisrelativesupplyholdsforanypricebetween3/2and5.Atthepriceof5,bothcountrieswouldharvestapples.Therelativesupplycurveisagainflatat5.Thus,therelativesupplycurveisstepshaped,flatattheprice3/2fromtherelativesupplyof0to1/2,verticalattherelativequantity1/2risingfrom3/2to5,andthenflatagainfrom1/2toinfinity.3.a.Therelativedemandcurveincludesthepoints(1/5,5),(1/2,2),(1,1),(2,1/2).b.Theequilibriumrelativepriceofapplesisfoundattheintersectionoftherelativedemandandrelativesupplycurves.Thisisthepoint(1/2,2),wheretherelative62 demandcurveintersectstheverticalsectionoftherelativesupplycurve.Thustheequilibriumrelativepriceis2.c.Homeproducesonlyapples,Foreignproducesonlybananas,andeachcountrytradessomeofitsproductfortheproductoftheothercountry.d.Intheabsenceoftrade,Homecouldgainthreebananasbyforegoingtwoapples,andForeigncouldgainbyoneappleforegoingfivebananas.Tradeallowseachcountrytotradetwobananasforoneapple.HomecouldthengainfourbananasbyforegoingtwoappleswhileForeigncouldgainoneapplebyforegoingonlytwobananas.Eachcountryisbetteroffwithtrade.4.TheincreaseinthenumberofworkersatHomeshiftsouttherelativesupplyschedulesuchthatthecornerpointsareat(1,3/2)and(1,5)insteadof(1/2,3/2)and(1/2,5).Theintersectionoftherelativedemandandrelativesupplycurvesisnowinthelowerhorizontalsection,atthepoint(2/3,3/2).Inthiscase,ForeignstillgainsfromtradebuttheopportunitycostofbananasintermsofapplesforHomeisthesamewhetherornotthereistrade,soHomeneithergainsnorlosesfromtrade.5.Thisanswerisidenticaltothatin3.Theamountof"effectivelabor"hasnotchangedsincethedoublingofthelaborforceisaccompaniedbyahalvingoftheproductivityoflabor.6.Thisstatementisjustanexampleofthepauperlaborargumentdiscussedinthechapter.Thepointisthatrelativewageratesdonotcomeoutofthinair;theyaredeterminedbycomparativeproductivityandtherelativedemandforgoods.Theboxinthechapterprovidesdatawhichshowsthestrongconnectionbetweenwagesandproductivity.Korea"slowwagepresumablyreflectsthefactthatKoreaislessproductivethantheUnitedStatesinmostindustries.Asthetestexampleillustrated,ahighlyproductivecountrythattradeswithalessproductive,low-wagecountrywillraise,notlower,itsstandardofliving.7.Theproblemwiththisargumentisthatitdoesnotusealltheinformationneededfordeterminingcomparativeadvantageinproduction:thiscalculationinvolvesthefourunitlaborrequirements(forboththeindustryandservicesectors,notjustthetwofortheservicesector).Itisnotenoughtocompareonlyservice"sunitlaborrequirements.Ifalsz,wherenandn*areasdefinedintheappendix.Thebalancedcurrentaccount(z=1)Marshall-Lernerconditionisaspecialcaseofthisgeneralcondition.Adepreciationislesslikelytoimprovethecurrentaccountthelargeritsinitialdeficitwhenn*islessthan1.Conversely,adepreciationismorelikelytocauseanimprovementinthecurrentaccountthelargeritsinitialsurplus,againforvaluesofn*lessthan1.Figure16-712.IfimportsconstitutepartoftheCPIthenafallinimportpricesduetoanappreciationofthecurrencywillcausetheoverallpriceleveltodecline.Thefallinthepricelevel62 raisesrealbalances.Asshownindiagram16-7,theshiftintheoutputmarketcurvefromDDtoD"D"ismatchedbyaninwardshiftoftheassetmarketequilibriumcurve.IfimportpricesarenotintheCPIandthecurrencyappreciationdoesnotaffectthepricelevel,theassetmarketcurveshiftstoA"A"andthereisnoeffectonoutput,evenintheshortrun.If,however,theoverallpricelevelfallsduetotheappreciation,theshiftintheassetmarketcurveissmaller,toA"A",andtheinitialequilibriumpoint,point1,hashigheroutputthantheoriginalequilibriumatpoint0.Overtime,pricesrisewhenoutputexceedsitslong-runlevel,causingashiftintheassetmarketequilibriumcurvefromA"A"toA"A",whichreturnsoutputtoitslong-runlevel.13.Anincreaseintheriskpremiumshiftstheassetmarketcurveoutandtotheright,allelseequal.Apermanentincreaseingovernmentspendingshiftstheassetmarketcurveinandtotherightsinceitcausestheexpectedfutureexchangeratetoappreciate.Apermanentriseingovernmentspendingalsocausesthegoodsmarketcurvetoshiftdownandtotherightsinceitraisesaggregatedemand.Inthecasewherethereisnoriskpremium,thenewintersectionoftheDDandAAcurveafterapermanentincreaseingovernmentspendingisatthefull-employmentlevelofoutputsincethisistheonlylevelconsistentwithnochangeinthelong-runpricelevel.Inthecasediscussedinthisquestion,however,thenominalinterestrateriseswiththeincreaseintheriskpremium.Therefore,outputmustalsobehigherthantheoriginalleveloffull-employmentoutput;ascomparedtothecaseinthetext,theAAcurvedoesnotshiftbyasmuchsooutputrises.14.Supposeoutputisinitiallyatfullemployment.ApermanentchangeinfiscalpolicywillcauseboththeAAandDDcurvestoshiftsuchthatthereisnoeffectonoutput.Nowconsiderthecasewheretheeconomyisnotinitiallyatfullemployment.ApermanentchangeinfiscalpolicyshiftstheAAcurvebecauseofitseffectonthelong-runexchangerateandshiftstheDDcurvebecauseofitseffectonexpenditures.Thereisnoreason,however,foroutputtoremainconstantinthiscasesinceitsinitialvalueisnotequaltoitslong-runlevel,andthusanargumentliketheoneinthetextthatshowstheneutralityofpermanentfiscalpolicyonoutputdoesnotcarrythrough.Infact,wemightexpectthataneconomythatbeginsinarecession(belowYf)wouldbestimulatedbacktowardsYfbyapositivepermanentfiscalshock.IfYdoesrisepermanently,wewouldexpectapermanentdropinthepricelevel(sinceMisconstant).ThisfallinPinthelongrunwouldmoveAAandDDbothout.Wecouldalsoconsiderthefactthatinthecasewherewebeginatfullemploymentandthereis62 noimpactonY,AAwasshiftingbackduetotherealappreciationnecessitatedbytheincreaseindemandforhomeproducts(asaresultoftheincreaseinG).IfthereisapermanentincreaseinY,therehasalsobeenarelativesupplyincreasewhichcanoffsettherelativedemandincreaseandweakentheneedforarealappreciation.Becauseofthis,AAwouldshiftbackbyless.Wedonotknowtheexacteffectwithoutknowinghowfarthelinesoriginallymove(thesizeoftheshock),butwedoknowthatwithouttherestrictionthatYisunchangedinthelongrun,theargumentinthetextcollapsesandwecanhavebothshortrunandlongruneffectsonY.15.Thetextshowsoutputcannotrisefollowingapermanentfiscalexpansionifoutputisinitiallyatitslong-runlevel.Usingasimilarargument,wecanshowthatoutputcannotfallfromitsinitiallong-runlevelfollowingapermanentfiscalexpansion.Apermanentfiscalexpansioncannothaveaneffectonthelong-runpricelevelsincethereisnoeffectonthemoneysupplyorthelong-runvaluesofthedomesticinterestrateandoutput.Whenoutputisinitiallyatitslong-runlevel,RequalsR*,YequalsYfandrealbalancesareunchangedintheshortrun.Ifoutputdidfall,therewouldbeexcessmoneysupplyandthedomesticinterestratewouldhavetofall,butthiswouldimplyanexpectedappreciationofthecurrencysincetheinterestdifferential(R-R*)wouldthenbenegative.This,however,couldonlyoccurifthecurrencyappreciatesinrealtermsasoutputrisesandtheeconomyreturnstolong-runequilibrium.Thisappreciation,however,wouldcausefurtherunemploymentandoutputwouldnotriseandreturnbacktoYf.Aswiththeexampleinthetext,thiscontradictionisonlyresolvedifoutputremainsatYf.62 CHAPTER17FIXEDEXCHANGERATESANDFOREIGNEXCHANGEINTERVENTIONANSWERSTOTEXTBOOKPROBLEMS1.Anexpansionofthecentralbank"sdomesticassetsleadstoanequalfallinitsforeignassets,withnochangeinthebank"sliabilities(orthemoneysupply).Theeffectonthebalance-of-paymentsaccountsismosteasilyunderstoodbyrecallinghowthefallinforeignreservescomesabout.Afterthecentralbankbuysdomesticassetswithmoneythereisinitiallyanexcesssupplyofmoney.Thecentralbankmustinterveneintheforeignexchangemarkettoholdtheexchangeratefixedinthefaceofthisexcesssupply:thebanksellsforeignassetsandbuysmoneyuntiltheexcesssupplyofmoneyhasbeeneliminated.Sinceprivateresidentsacquirethereservesthecentralbankloses,thereisanon-centralbankcapitaloutflow(acapital-accountdebit)equaltotheincreaseinforeignassetsheldbytheprivatesector.Theoffsettingcreditisthereductionincentralbankholdingsofforeignassets,anofficialcapitalinflow.2.Anincreaseingovernmentspendingraisesincomeandalsomoneydemand.Thecentralbankpreventstheinitialexcessmoneydemandfromappreciatingthedomesticcurrencybypurchasingforeignassetsfromthedomesticpublic.Centralbankforeignassetsrise,asdothecentralbank"sliabilitiesandwiththem,themoneysupply.Thecentralbank"sadditionalreserveholdingsshowupasanofficialcapitaloutflow,acapital-accountdebit.Offsettingthisdebitisthecapitalinflow(acredit)associatedwiththepublic"sequalreductioninitsownforeignassets.3.Aone-timeunexpecteddevaluationinitiallyincreasesoutput;theoutputincrease,inturn,raisesmoneydemand.Thecentralbankmustaccommodatethehighermoneydemandbybuyingforeignassetswithdomesticcurrency,astepthatraisesthecentralbank"sliabilities(andthehomemoneysupply)atthesametimeasitincreasesthebank"sforeignassets.Theincreaseinofficialforeignreservesisanofficialcapitaloutflow;itismatchedinthebalanceofpaymentsaccountsbytheequalcapitaloutflowassociatedwiththepublic"sownreductioninnetforeignassetholdings.(Thepublicmustexchangeforeignassetsforthemoneyitbuysfromthecentralbank,either62 bysellingforeignassetsorbyborrowingforeigncurrencyabroad.Eithercourseofactionisacapitalinflow.)Amoresubtleissueisthefollowing:whenthepriceofforeigncurrencyisraised,thevalueoftheinitialstockofforeignreservesriseswhenmeasuredintermsofdomesticcurrency.Thiscapitalgaininitselfraisescentral-bankforeignassets(whichweremeasuredindomesticcurrencyunitsinouranalysis)--sowhereisthecorrespondingincreaseinliabilities?Doesthecentralbankinjectmorecurrencyorbank-systemreservesintotheeconomytobalanceitsbalancesheet?Theansweristhatcentralbanksgenerallycreatefictionalaccountingliabilitiestooffsettheeffectofexchange-ratefluctuationsonthehome-currencyvalueofinternationalreserves.Thesecapitalgainsandlossesdonotautomaticallyleadtochangesinthemonetarybase.4.Asshowninfigure17-1,adevaluationcausestheAAcurvetoshifttoA"A"whichreflectsanexpansioninbothoutputandthemoneysupplyintheeconomy.Diagram17-1alsocontainsanXXcurvealongwhichthecurrentaccountisinbalance.Theinitialequilibrium,atpoint0,wasontheXXcurve,reflectingthefactthatthecurrentaccountwasinbalancethere.Afterthedevaluation,thenewequilibriumpointisaboveandtotheleftoftheXXcurve,intheregionwherethecurrentaccountisinsurplus.Withfixedprices,adevaluationimprovesaneconomy"scompetitiveness,increasingitsexports,decreasingitsimportsandraisingthelevelofoutput.Figure17-15.a.Germanyclearlyhadtheabilitytochangethedollar/DMexchangesimplybyalteringitsmoneysupply.Thefactthat"billionsofdollarsworthofcurrenciesaretradedeach62 day"isirrelevantbecauseexchangeratesequilibratemarketsforstocksofassets,andthetradevolumesmentionedareflows.b.Onemustdistinguishbetweensterilizedandnonsterilizedintervention.Theevidenceregardingsterilizedinterventionsuggeststhatitseffectsarelimitedtothesignalingaspect.Thisaspectmaywellbemostimportantwhenmarketsare"unusuallyerratic,"andthesignalscommunicatedmaybemostcrediblewhenthecentralbankisnotattemptingtoresistclear-cutmarkettrends(whichdependonthecompleterangeofgovernmentmacroeconomicpolicies,amongotherfactors).Nonsterilizedintervention,however,isapowerfulinstrumentinaffectingexchangerates.c.The"psychologicaleffect"ofa"statedintention"tointervenemaybemorepreciselystatedasaneffectontheexpectedfutureleveloftheexchangerate.d.Arewritemightgoasfollows:TokeepthedollarfromfallingagainsttheWestGermanmark,theEuropeancentralbankswouldhavetosellmarksandbuydollars,aprocedureknownasintervention.Becausetheavailablestocksofdollarandmarkbondsaresolarge,itisunlikelythatsterilizedinterventioninthedollar/markmarket,evenifcarriedoutbythetwomosteconomicallyinfluentialmembersoftheEuropeanCommunity--BritainandWestGermany--wouldhavemucheffect.Thereasonisthatsterilizedinterventionchangesonlyrelativebondsuppliesandleavesnationalmoneysuppliesunchanged.InterventionbytheUnitedStatesandGermanythatwasnotsterilized,however,wouldaffectthosecountries"moneysuppliesandhaveasignificantimpactonthedollar/markrate.Economistsbelievethatthedirectinfluenceofsterilizedinterventiononexchangeratesissmallcomparedwiththatofnonsterilizedintervention.Evensterilizedinterventioncanaffectexchangerates,however,throughitsindirectinfluenceonmarketexpectationsaboutfuturepolicies.Suchpsychologicaleffects,whichcanresultfromjustthestatedintentionoftheCommunity"scentralbankstointervene,candisruptthemarketbyconfusingtradersaboutofficialplans.Thesignalingeffectofinterventionismostlikelytobenefittheauthoritieswhentheirothermacroeconomicpoliciesarealreadybeingadjustedtopushtheexchangerateinthedesireddirection.6.Theproblemscausedbyexchange-ratevariabilityarediscussedatlengthinChapter19;somemonetarypolicyautonomymightwillinglybesacrificedtoreducetheseproblems.Policy-makersmightalsosacrificeautonomytoenterintocooperative62 arrangementswithforeignpolicy-makersthatreducetheriskof"beggar-thy-neighbor"policyactions(seetheappendixtoChapter19).7.Byraisingoutput,fiscalexpansionraisesimportsandthusworsensthecurrent-accountbalance.Theimmediatefallinthecurrentaccountissmallerthanunderfloating,however,becausethecurrencydoesnotappreciateandcrowdoutnetexports.8.Thereasonthattheeffectsoftemporaryandpermanentfiscalexpansionsdifferunderfloatingexchangeratesisthatatemporarypolicyhasnoeffectontheexpectedexchangeratewhileapermanentpolicydoes.TheAAcurveshiftswithachangeintheexpectedexchangerate.Intermsofthediagram,apermanentfiscalexpansioncausestheAAcurvetoshiftdownandtotheleftwhich,combinedwiththeoutwardshiftintheDDcurve,resultsinnochangeinoutput.Withfixedexchangerates,however,thereisnochangeintheexpectedexchangeratewitheitherpolicysincetheexchangerateis,bydefinition,fixed.Inresponsetobothtemporaryandpermanentfiscalexpansions,thecentralbankmustexpandthemoneysupply(shiftAAout)topreventthecurrencyfromappreciating(duetotheshiftoutintheDDcurve).Thus,YgoesupandEdoesnotchangeafterapermanentortemporaryfiscalexpansionwhenexchangeratesarefixed.9.Byexpandingoutput,adevaluationautomaticallyraisesprivatesaving,sincepartofanyincreaseinoutputissaved.Governmenttaxreceiptsrisewithoutput,sothebudgetdeficitislikelytodecline,implyinganincreaseinpublicsaving.Wehaveassumedinvestmenttobeconstantinthemaintext.Ifinvestmentinsteaddependsnegativelyontherealinterestrate(asintheIS-LMmodel),investmentrisesbecausedevaluationraisesinflationaryexpectationsandthuslowerstherealinterestrate.(Thenominalinterestrateremainsunchangedattheworldlevel.)Theinterest-sensitivecomponentsofconsumptionspendingalsorise,andiftheseinterest-rateeffectsarestrongenough,acurrent-accountdeficitcouldresult.10.Animporttariffraisesthepriceofimportstodomesticconsumersandshiftsconsumptionfromimportstodomesticallyproducedgoods.ThiscausesanoutwardshiftintheDDcurve,increasingoutputandappreciatingthecurrency.Sincethecentralbankcannotallowexchangeratestochange,itmustincreasethemoneysupply,anactiondepictedinthediagramasanoutwardshiftintheAAschedule.62 Correspondingtothismonetaryexpansionisabalanceofpaymentssurplusandanequalincreaseinofficialforeignreserves.Thefallinimportsforonecountryimpliesafallinexportsforanothercountry,andacorrespondinginwardshiftofthatcountry"sDDcurvenecessitatingamonetarycontractionbythecentralbanktopreserveitsfixedexchangerate.Ifallcountriesimposeimporttariffs,thennocountrysucceedsinturningworlddemandinitsfavororingainingreservesthroughanimprovementinitsbalanceofpayments.Tradevolumesshrink,however,andallcountrieslosesomeofthegainsfromtrade.11.Ifthemarketexpectsthedevaluationto"stick,"thehomenominalinterestratefallstotheworldlevelafterward,moneydemandrises,andthecentralbankbuysforeignassetswithdomesticmoneytopreventexcessmoneydemandfromappreciatingthecurrency.Thecentralbankthusgainsofficialreserves,accordingtoourmodel.Evenifanotherdevaluationwastooccurinthenearfuture,reservesmightbegainedifthefirstdevaluationloweredthedepreciationexpectedforthefutureand,withit,thehomenominalinterestrate.Aninadequateinitialdevaluationcould,however,increasethedevaluationexpectedforthefuture,withoppositeeffectsonthebalanceofpayments.12.IftheBankofJapanholdsU.S.dollarsinsteadofTreasurybills,theadjustmentprocessissymmetric.AnypurchaseofdollarsbytheBankofJapanleadstoafallintheU.S.moneysupplyasthedollarbillsgooutofcirculationandintotheBankofJapan’svaults.AJapanesebalanceofpaymentssurplusincreasestheBankofJapan’smoneysupply(ifthereisnosterilization)andreducestheU.S.moneysupplyatthesametime.13.Acentralbankthatismaintainingafixedexchangeratewillrequireanadequatebufferstockofforeignassetsonhandduringperiodsofpersistentbalanceofpaymentsdeficits.Ifacentralbankdepletesitsstockofforeignreserves,itisnolongerabletokeepitsexchangeratefromdepreciatinginresponsetopressuresarisingfromabalanceofpaymentsdeficit.Simplyput,acentralbankcaneitherchoosetheexchangerateandallowitsreserveholdingstochangeorchoosetheamountofforeignreservesitholdsandallowtheexchangeratetofloat.Ifitlosestheabilitytocontroltheamountofreservesbecausetheprivatedemandforthemexceedsitssupply,itcannolongercontroltheexchangerate.Thus,acentralbankmaintainingafixedexchangerateisnotindifferentaboutusingdomesticorforeignassetstoimplementmonetarypolicy.62 14.AnESFinterventiontosupporttheyeninvolvesanexchangeofdollar-denominatedassetsinitiallyownedbytheESFforyen-denominatedassetsinitiallyownedbytheprivatesector.Sincethisisanexchangeofonetypeofbondforanotherthereisnochangeinthemoneysupplyandthusthistransactionisautomaticallysterilized.Thistransactionincreasestheoutstandingstockofdollar-denominatedassetsheldbytheprivatesector,whichincreasestheriskpremiumondollar-denominatedassets.15.Themonetaryauthoritiescancombineachangeinthemoneysupplywithapurchaseorsaleofitsforeignassetstokeeptheexchangeratefixedwhilealteringthedomesticinterestrate.Forexample,themonetaryauthoritieslowerdomesticinterestratesbyincreasingthemoneysupply.Tomaintainafixedvalueoftheexchangerate,themonetaryauthoritywouldalsosellforeignassetsandpurchasedomesticassets.Inthefigurebelow,theincreaseinthemoneysupplylowerstheinterestratefromR0toR".Thepurchaseofdomesticassetsandsaleofforeignassets,whilehavingnofurthereffectonthemoneysupply,lowerstheriskpremium,shiftstheinterestparityschedulefromIItoI"I"andmaintainstheexchangerateatE0.Figure17-262'