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首页 范里安中级微观摘要

范里安中级微观摘要.pdf

范里安中级微观摘要

kralsolander
2011-04-13 0人阅读 举报 0 0 0 暂无简介

简介:本文档为《范里安中级微观摘要pdf》,可适用于高等教育领域

ChapterChapterTheMarketThischapterwaswrittensoIwouldhavesomethingtotalkaboutonthe�rstdayofclassIwantedtogivestudentsanideaofwhateconomicswasallabout,andwhatmylectureswouldbelike,andyetnothaveanythingthatwasreallycriticalforthecourse(AtMichigan,studentsarestillshoppingaroundonthe�rstday,andagoodnumberofthemwon’tnecessarilybeatthelecture)IchosetodiscussahousingmarketsinceitgivesawaytodescribeanumberofeconomicideasinverysimplelanguageandgivesagoodguidetowhatliesaheadInthischapterIwasdeliberatelylookingforsurprisingresults|analyticinsightsthatwouldn’tarisefromjustthinking"aboutaproblemThetwomostsurprisingresultsthatIpresentedarethecondominiumexampleandthetaxexampleinSectionItisworthemphasizinginclassjustwhytheseresultsaretrue,andhowtheyillustratethepowerofeconomicmodelingItalsomakessensetodescribetheirlimitationsSupposethateverycondominiumconversioninvolvedknockingoutthewallsandcreatingtwoapartmentsThenwhatwouldhappentothepriceofapartmentsSupposethatthecondominiumsattractedsuburbaniteswhowouldn’totherwiseconsiderrentinganapartmentIneachofthesecases,thepriceofremainingapartmentswouldrisewhencondominiumconversiontookplaceThepointofasimpleeconomicmodelofthesortconsideredhereistofocusourthoughtsonwhattherelevante�ectsare,nottocometoaonceandforallconclusionabouttheurbanhousingmarketTherealinsightthatiso�eredbytheseexamplesisthatyouhavetoconsiderboththesupplyandthedemandsideoftheapartmentmarketwhenyouanalyzetheimpactofthisparticularpolicyTheonlyconceptthatthestudentsseemtohavetroublewithinthischapteristheideaofParetoe�ciencyIusuallytalkabouttheideaalittlemorethanisinthebookandrephraseitafewtimesButthenItellthemnottoworryaboutittoomuch,sincewe’lllookatitingreatdetaillaterinthecourseTheworkbookproblemshereareprettystraightforwardThebiggestproblemisgettingthestudentstodrawthetrue(discontinuous)demandcurve,asinFigure,ratherthanjusttosketchinadownwardslopingcurveasinFigureThisisagoodtimetoemphasizetothestudentsthatwhentheyaregivennumbersdescribingacurve,theyhavetousethenumbers|theycan’tjustsketchinanyoldshapeChapterHighlightsTheMarketAExampleofaneconomicmodel|themarketforapartmentsmodelsaresimpli�cationsofrealityforexample,assumeallapartmentsareidenticalsomeareclosetotheuniversity,othersarefarawaypriceofouterringapartmentsisexogenous|determinedoutsidethemodelpriceofinnerringapartmentsisendogenous|determinedwithinthemodelBTwoprinciplesofeconomicsoptimizationprinciple|peoplechooseactionsthatareintheirinterestequilibriumprinciple|people’sactionsmusteventuallybeconsistentwitheachotherCConstructingthedemandcurvelineupthepeoplebywillingnesstopaySeeFigureforlargenumbersofpeople,thisisessentiallyasmoothcurveasinFigureDSupplycurvedependsontimeframebutwe’lllookattheshortrun|whensupplyofapartmentsis�xedEEquilibriumwhendemandequalssupplypricethatclearsthemarketFComparativestaticshowdoesequilibriumadjustwheneconomicconditionschangecomparative"|comparetwoequilibriastatics"|onlylookatequilibria,notatadjustmentexample|increaseinsupplylowerspriceseeFigureexample|createcondoswhicharepurchasedbyrentersnoe�ectonpriceseeFigureGOtherwaystoallocateapartmentsdiscriminatingmonopolistordinarymonopolistrentcontrolHComparingdi�erentinstitutionsneedacriteriontocomparehowe�cientthesedi�erentallocationmethodsareanallocationisParetoe�cientifthereisnowaytomakesomegroupofpeoplebettero�withoutmakingsomeoneelseworseo�ifsomethingisnotParetoe�cient,thenthereissomewaytomakesomepeoplebettero�withoutmakingsomeoneelseworseo�ifsomethingisnotParetoe�cient,thenthereissomekindofwaste"inthesystemICheckinge�ciencyofdi�erentmethodsfreemarket|e�cientdiscriminatingmonopolist|e�cientordinarymonopolist|note�cientrentcontrol|note�cientChapterJEquilibriuminlongrunsupplywillchangecanexaminee�ciencyinthiscontextaswellChapterHighlightsChapterBudgetConstraintMostofthematerialhereisprettystraightforwardDrivehometheformulafortheslopeofthebudgetline,emphasizingthederivationonpageTrysomedi�erentnotationtomakesurethattheyseetheideaofthebudgetline,anddon’tjustmemorizetheformulasIntheworkbook,weuseanumberofdi�erentchoicesofnotationforpreciselythisreasonItisalsoworthpointingoutthattheslopeofalinedependsonthe(arbitrary)choiceofwhichvariableisplottedontheverticalaxisItissurprisinghowoftenconfusionarisesonthispointStudentssometimeshaveproblemswiththeideaofanumerairegoodTheyunderstandthealgebra,buttheydon’tunderstandwhenitwouldbeusedOneniceexampleisinforeigncurrencyexchangeIfyouhaveEnglishpoundsandAmericandollars,thenyoucanmeasurethetotalwealththatyouhaveineitherdollarsorpoundsbychoosingoneortheotherofthetwogoodsasnumeraireIntheworkbook,studentssometimesgetthrowninexerciseswhereoneofthegoodshasanegativeprice,sothebudgetlinehasapositiveslopeThiscomesfromtryingtomemorizeformulasand�guresratherthanthinkingabouttheproblemThisisagoodexercisetogooverinordertowarnstudentsaboutthedangersofrotelearning!BudgetConstraintAConsumertheory:consumerschoosethebestbundlesofgoodstheycana�ordthisisvirtuallytheentiretheoryinanutshellbutthistheoryhasmanysurprisingconsequencesBTwopartstotheorycana�ord"|budgetconstraintbest"|accordingtoconsumers’preferencesChapterCWhatdowewanttodowiththetheorytestit|seeifitisadequatetodescribeconsumerbehaviorpredicthowbehaviorchangesaseconomicenvironmentchangesuseobservedbehaviortoestimateunderlyingvaluesa)costbene�tanalysisb)predictingimpactofsomepolicyDConsumptionbundle(xx)|howmuchofeachgoodisconsumed(pp)|pricesofthetwogoodsm|moneytheconsumerhastospendbudgetconstraint:pxpx�mall(xx)thatsatisfythisconstraintmakeupthebudgetsetoftheconsumerSeeFigureETwogoodstheoryworkswithmorethantwogoods,butcan’tdrawpicturesoftenthinkofgood(say)asacompositegood,representingmoneytospendonothergoodsbudgetconstraintbecomespxx�mmoneyspentongood(px)plusthemoneyspentongood(x)hastobelessthanorequaltotheamountavailable(m)FBudgetlinepxpx=malsowrittenasx=m=p−(p=p)xbudgetlinehasslopeof−p=pandverticalinterceptofm=psetx=to�ndverticalintercept(m=p)setx=to�ndhorizontalintercept(m=p)slopeofbudgetlinemeasuresopportunitycostofgood|howmuchofgoodyoumustgiveupinordertoconsumemoreofgoodGChangesinbudgetlineincreasingmmakesparallelshiftoutSeeFigureincreasingpmakesbudgetlinesteeperSeeFigureincreasingpmakesbudgetlineflatterjustseehowinterceptschangemultiplyingallpricesbytisjustlikedividingincomebytmultiplyingallpricesandincomebytdoesn’tchangebudgetlinea)aperfectlybalancedinflationdoesn’tchangeconsumptionpossibilities"HThenumerairecanarbitrarilyassignonepriceavalueofandmeasureotherpricerelativetothatusefulwhenmeasuringrelativepriceseg,Englishpoundsperdollar,dollarsversusdollars,etcITaxes,subsidies,andrationingquantitytax|taxleviedonunitsbought:ptvaluetax|taxleviedondollarsspent:p�pAlsoknownasadvaloremtaxsubsidies|oppositeofataxa)p−sb)(−�)pChapterHighlightslumpsumtaxorsubsidy|amountoftaxorsubsidyisindependentoftheconsumer’schoicesAlsocalledaheadtaxorapolltaxrationing|can’tconsumemorethanacertainamountofsomegoodJExample|foodstampsbeforewasanadvaloremsubsidyonfooda)paidacertainamountofmoneytogetfoodstampswhichwereworthmorethantheycostb)somerationingcomponent|couldonlybuyamaximumamountoffoodstampsaftergotastraightlumpsumgrantoffoodcouponsNotthesameasapurelumpsumgrantsincecouldonlyspendthecouponsonfoodChapterChapterPreferencesThischapterismoreabstractandthereforeneedssomewhatmoremotivationthanthepreviouschaptersItmightbeagoodideatotalkaboutrelationsingeneralbeforeintroducingtheparticularideaofpreferencerelationsTrytherelationsoftaller,"andheavier,"andtallerandheavier"Pointoutthattallerandheavier"isn’tacompleterelation,whiletheothertwoareThisgeneraldiscussioncanmotivatethegeneralideaofpreferencerelationsMakesurethatthestudentslearnthespeci�cexamplesofpreferencessuchasperfectsubstitutes,perfectcomplements,etcTheywillusetheseexamplesmany,manytimesinthenextfewweeks!Whendescribingtheideasofperfectsubstitutes,emphasizethatthede�ningcharacteristicisthattheslopeoftheindi�erencecurvesisconstant,notthatitis−Inthetext,Ialwaysstickwiththecasewheretheslopeis−,butintheworkbook,weoftentreatthegeneralcaseThesamewarninggoeswiththeperfectcomplementscaseIworkoutthesymmetriccaseinthetextandtrytogetthestudentstodotheasymmetriccaseintheworkbookThede�nitionofthemarginalrateofsubstitutionisfraughtwithsignconfusion"ShouldtheMRSbede�nedasanegativeorapositivenumberI’vechosentogivetheMRSitsnaturalsigninthebook,butIwarnthestudentsthatmanyeconomiststendtospeakoftheMRSintermsofabsolutevalueExample:diminishingmarginalrateofsubstitutionreferstoasituationwheretheabsolutevalueoftheMRSdecreasesaswemovealonganindi�erencecurveTheactualvalueoftheMRS(anegativenumber)isincreasinginthismovement!StudentsoftenbegintohaveproblemswiththeworkbookexerciseshereThe�rstconfusiontheyhaveisthattheygetmixedupabouttheideathatindi�erencecurvesmeasurethedirectionswherepreferencesareconstant,andinsteaddrawlinesthatindicatethedirectionsthatpreferencesareincreasingThesecondproblemthattheyhaveisinknowingwhentodrawjustarbitrarycurvesthatqualitativelydepictsomebehaviororother,andwhentodrawexactshapesTryaskingyourstudentstodrawtheirindi�erencecurvesbetween�vedollarbillsandonedollarbillsO�ertotradewiththembasedonwhattheydrawInadditiontogettingthemtothink,thisisagoodwaytosupplementyourfacultysalaryChapterHighlightsPreferencesAPreferencesarerelationshipsbetweenbundlesifaconsumerwouldchoosebundle(xx)when(yy)isavailable,thenitisnaturaltosaythatbundle(xx)ispreferredto(yy)bythisconsumerpreferenceshavetodowiththeentirebundleofgoods,notwithindividualgoodsBNotation(xx)�(yy)meansthexbundleisstrictlypreferredtotheybundle(xx)�(yy)meansthatthexbundleisregardedasindi�erenttotheybundle(xx)�(yy)meansthexbundleisatleastasgoodas(preferredtoorindi�erentto)theybundleCAssumptionsaboutpreferencescomplete|anytwobundlescanbecomparedreflexive|anybundleisatleastasgoodasitselftransitive|ifX�YandY�Z,thenX�Za)transitivitynecessaryfortheoryofoptimalchoiceDIndi�erencecurvesgraphthesetofbundlesthatareindi�erenttosomebundleSeeFigureindi�erencecurvesarelikecontourlinesonamapnotethatindi�erencecurvesdescribingtwodistinctlevelsofpreferencecannotcrossSeeFigurea)proof|usetransitivityEExamplesofpreferencesperfectsubstitutesFigurea)redpencilsandbluepencilspintsandquartsb)constantrateoftradeo�betweenthetwogoodsperfectcomplementsFigurea)alwaysconsumedtogetherb)rightshoesandleftshoesco�eeandcreambadsFigureneutralsFiguresatiationorblisspointFigureFWellbehavedpreferencesmonotonicity|moreofeithergoodisbettera)impliesindi�erencecurveshavenegativeslopeFigureconvexity|averagesarepreferredtoextremesFigurea)slopegetsflatterasyoumovefurthertorightb)exampleofnonconvexpreferencesGMarginalrateofsubstitutionslopeoftheindi�erencecurveMRS=�x=�xalonganindi�erencecurveFiguresignproblem|naturalsignisnegative,sinceindi�erencecurveswillgenerallyhavenegativeslopemeasureshowtheconsumeriswillingtotradeo�consumptionofgoodforconsumptionofgoodFigureChaptermeasuresmarginalwillingnesstopay(giveup)a)notthesameashowmuchyouhavetopayb)buthowmuchyouwouldbewillingtopayChapterHighlightsChapterUtilityInthischapter,thelevelofabstractionkicksupanothernotchStudentsoftenhavetroublewiththeideaofutilityItissometimeshardfortrainedeconomiststosympathizewiththemsu�ciently,sinceitseemslikesuchanobviousnotiontousHereisawaytoapproachthesubjectSupposethatwereturntotheideaoftheheavierthan"relationdiscussedinthelastchapterThinkofhavingabigbalancescalewithtwotraysYoucanputsomeoneoneachsideofthebalancescaleandseewhichpersonisheavier,butyoudon’thaveanystandardizedweightsNeverthelessyouhaveawaytodeterminewhetherxisheavierthanyNowsupposethatyoudecidetoestablishascaleYougetabunchofstones,checkthattheyareallthesameweight,andthenmeasuretheweightofindividualsinstonesItisclearthatxisheavierthanyifx’sweightinstonesisheavierthany’sweightinstonesSomebodyelsemightusedi�erentunitsofmeasurements|kilograms,pounds,orwhateverItdoesn’tmakeanydi�erenceintermsofdecidingwhoisheavierAtthispointitiseasytodrawtheanalogywithutility|justaspoundsgiveawaytorepresenttheheavierthan"ordernumerically,utilitygivesawaytorepresentthepreferenceordernumericallyJustastheunitsofweightarearbitrary,soaretheunitsofutilityThisanalogycanalsobeusedtoexploretheconceptofapositivemonotonictransformation,aconceptthatstudentshavegreattroublewithTellthemthatamonotonictransformationisjustlikechangingunitsofmeasurementintheweightexampleHowever,itisalsoimportantforstudentstounderstandthatnonlinearchangesofunitsarepossibleHereisaniceexampletoillustratethisSupposethatwoodisalwayssoldinpilesshapedlikecubesThinkoftherelationonepilehasmorewoodthananother"Thenyoucanrepresentthisrelationbylookingatthemeasureofthesidesofthepiles,thesurfaceareaofthepiles,orthevolumeofthepilesThatis,x,x,orxgivesexactlythesamecomparisonbetweenthepilesEachofthesenumbersisadi�erentrepresentationoftheutilityofacubeofwoodBesuretogoovercarefullytheexampleshereTheCobbDouglasexampleisanimportantone,sinceweuseitsomuchintheworkbookEmphasizethatitisjustanicefunctionalformthatgivesconvenientexpressionsBesuretoChapterelaborateontheideathatxaxbisthegeneralformforCobbDouglaspreferences,butvariousmonotonictransformations(eg,thelog)canmakeitlookquitedi�erentIt’sagoodideatocalculatetheMRSforafewrepresentationsoftheCobbDouglasutilityfunctioninclasssothatpeoplecanseehowtodothemand,moreimportantly,thattheMRSdoesn’tchangeasyouchangetherepresentationofutilityTheexampleattheendofthechapter,oncommutingbehavior,isaveryniceoneIfyoupresentitright,itwillconvinceyourstudentsthatutilityisanoperationalconceptTalkabouthowthesamemethodscanbeusedinmarketingsurveys,surveysofcollegeadmissions,etcTheexercisesintheworkbookforthischapterareveryimportantsincetheydrivehometheideasAlotoftimes,studentsthinkthattheyunderstandsomepoint,buttheydon’t,andtheseexerciseswillpointthatouttothemItisagoodideatoletthestudentsdiscoverforthemselvesthatasure�rewaytotellwhetheroneutilityfunctionrepresentsthesamepreferencesasanotheristocomputethetwomarginalrateofsubstitutionfunctionsIftheydon’tgetthisideaontheirown,youcanposeitasaquestionandleadthemtotheanswerUtilityATwowaysofviewingutilityoldwaya)measureshowsatis�ed"youare)notoperational)manyotherproblemsnewwaya)summarizespreferencesb)autilityfunctionassignsanumbertoeachbundleofgoodssothatmorepreferredbundlesgethighernumbersc)thatis,u(xx)>u(yy)ifandonlyif(xx)�(yy)d)onlytheorderingofbundlescounts,sothisisatheoryofordinalutilitye)advantages)operational)givesacompletetheoryofdemandBUtilityfunctionsarenotuniqueifu(xx)isautilityfunctionthatrepresentssomepreferences,andf(�)isanyincreasingfunction,thenf(u(xx))representsthesamepreferenceswhyBecauseu(xx)>u(yy)onlyiff(u(xx))>f(u(yy))soifu(xx)isautilityfunctionthenanypositivemonotonictransformationofitisalsoautilityfunctionthatrepresentsthesamepreferencesCConstructingautilityfunctioncandoitmechanicallyusingtheindi�erencecurvesFigurecandoitusingthemeaning"ofthepreferencesDExamplesutilitytoindi�erencecurvesa)easy|justplotallpointswheretheutilityisconstantindi�erencecurvestoutilityexamplesa)perfectsubstitutes|allthatmattersistotalnumberofpencils,sou(xx)=xxdoesthetrickChapterHighlights)canuseanymonotonictransformationofthisaswell,suchaslog(xx)b)perfectcomplements|whatmattersistheminimumoftheleftandrightshoesyouhave,sou(xx)=minfxxgworksc)quasilinearpreferences|indi�erencecurvesareverticallyparallelFigure)utilityfunctionhasformu(xx)=v(x)xd)CobbDouglaspreferencesFigure)utilityhasformu(xx)=xbxc)convenienttotaketransformationf(u)=ubcandwritexbbcxcbc)orxax−a,wherea=b=(bc)EMarginalutilityextrautilityfromsomeextraconsumptionofoneofthegoods,holdingtheothergood�xedthisisaderivative,butaspecialkindofderivative|apartialderivativethisjustmeansthatyoulookatthederivativeofu(xx)keepingx�xed|treatingitlikeaconstantexamplesa)ifu(xx)=xx,thenMU=u=x=b)ifu(xx)=xax−a,thenMU=u=x=axa−x−a

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