微观经济学义PPT

Chapter12 TheEconomicsofInformation LearningObjectives ExplainhowmiddlemenaddvaluetomarkettransactionsUsetheconceptofrationalsearchtofindtheoptimalamountofinformationmarketparticipantsshouldobtainDefineasymmetricinformationanddescribehowitleadstothelemonsproblemDiscusshowadvertising conspicuousconsumption statisticaldiscrimination andotherdevicesareresponsestoasymmetricinformation InformationandtheInvisibleHand AllpartieshaveallrelevantinformationWithoutfreeinformation marketresultsarenotefficientBargainingforabowlinKashmirPartiesmustdecidehowmuchinformationtogatherInformationgatheringstrategiesdiffer TheMiddlemanAddsValue BuyerssometimeschooseamongseveralversionofaproductEachhascomplexfeaturesetsResearchoptionsCompanywebsiteAskfriendsandfamilyConsumerReports onlineproductreviewsVisitstores ecommercesites BuyingSkis SkisRUsrecommend 600SalomonX Scream9skisSalesrepseemsknowledgeableYournextmoveisThankthemanddomoreresearchTrustthesalesrepandbuythemGohomeandbuyatthebestpriceonline 400 EvaluatetheimportanceofImmediatepossessionBestpricePost salesserviceandsupport TheValueoftheMiddleman SalesrepresentativessupplyinformationtobuyersManufacturerscanofferdirectsalestobypassmiddlemenInformationmakesmarketsmoreefficientPurchasingthebowlinKashmir SellingBabeRuth ElliswantstosellaBabeRuthbaseballcard Hisreservationpriceis 300Anadinthelocalnewspapercost 5eBaycostis5 oftheInternetauctionpriceThemaximumpriceinthelocalmarketis 400TwoeBayshoppershavesecretreservationpricesof 800and 900 respectively SellingBabeRuth BenefitsofeBayCardsellsfor 800oneBayless 40commissionEllisnets 760 460abovehisreservationpriceBuyersurplusis 100LocaloptionisinferiorCardsellsfor 400less 5costofadEllisnets 395 95morethanhisreservationpriceBuyersurplusis 0Economicsurplusisincreasedwhenaproductgoestothepersonwhovaluesitthemost TheOptimalAmountofInformation MoreinformationisbetterthanlessGatheringinformationhasacostMarginalbenefitstartshigh thenfallsrapidlyLow HangingFruitPrincipleMarginalcoststartslow thenincreasesOptimalamountofinformationisI whereMC MB FreeRiderProblem Afree riderproblemexistswhennon payerscannotbeexcludedfromconsumingagoodInterfereswithincentivesMarketquantityisbelowsocialoptimumStoresbearthecostoftrainingsalesrepsonmerchandiseShoppersusesalesrepsasinformationsourceThensomeshoppersbuyelsewhereStoreisunabletocapturesomeofthevalueitdeliveredtotheshopper afree riderproblem TheLastBookstore IndependentbookstoresdifferentiatethemselveswithpersonalizedserviceOffermoreinformationandrecommendationsthanBarnesquickdeliveryOnlinesalesfurtherreducesalesinindependentstores RationalSearchGuidelines AdditionalsearchtimeismorelikelytobeworthwhileforexpensiveitemsthancheaponesApartmentsearchinParis TexasinvolveslesstimethanParis FranceTexashaslowerrentsandnarrowerpricerangePricespaidwillbehigherwhenthecostofasearchishigherTwobuyers onlyonewithacarBuyerwiththecarwilllookatmorepianosbeforebuying GambleInherentinSearch AdditionalsearchhascoststhatarecertainBenefitsareuncertainbenefitsAdditionalsearchhaselementsofagambleAgamblehasanumberofpossibleoutcomesEachoutcomehasaprobabilitythatitwilloccur GambleInherentinSearch Theexpectedvalueofagambleisthesumof thepossibleoutcomestimestheirrespectiveprobability AfairgamblehasanexpectedvalueofzeroAbetter than fairgamblehasapositiveexpectedvalue RiskPreferences Arisk neutralpersonwouldacceptanygamblethatisfairorbetter than fairArisk aversepersonwouldrefuseanyfairgamble SanFranciscoApartmentSearch Youneedaone monthsubletinSanFranciscoOnetypeofapartmentrentsfor 400anditis80 oftheavailablemarketTheothertyperentsfor 360andmakesup20 ofthemarketYoumustvisittheapartmenttogettherentalrateCostpervisitis 6Youarerisk neutral SanFranciscoApartmentSearch Thefirstapartmentyouvisitisthe 400versionLookatthenextapartmentifthegambleisatleastfairTwooutcomestothegambleYoufindalower pricedapartmentandyournetbenefitis 34with20 probabilityYoufindanother 400apartmentandyournetbenefitis 6with80 probabilityExpectedvalueofthegambleis 34 0 20 6 0 80 2Keepsearching CommitmentProblemsandSearch SomesearchesareforcircumstancesrequiringcommitmentoversomeperiodoftimeLeasinganapartmentTakingajobGettingmarriedSearchiscostlyandthereforelimitedPeopleendtheirsearcheswhenthemarginalcostofsearchingexceedsthemarginalbenefitBUT whatifyoufallintoabetteroption CommitmentProblemsandSearch Ifinformationwerefreelyavailable therewouldbenocommitmentproblemContractsareusedtobindpartiestogetherANDContractscarrypenaltiesforbreakingthearrangementPeopleterminatetheirsearchbecauseinformationgatheringiscostlyUndersomecircumstances onepartymayrationallychoosetoterminatetheagreementandpaythepenalties AsymmetricInformation AsymmetricinformationoccurswheneitherthebuyerorsellerIsbetterinformedaboutthegoodsinthemarketMutuallybeneficialtradesmaynotoccurAsellermightknowthatamurderwascommittedinahouseofferedforsaleBuyerdoesnotknow PrivateSaleofaUsedCar Jane sMiataisinexcellentconditionJane sreservationpriceis 10 000BlueBookvalueis 8 000TomwantstobuyaMiataHisreservationpriceis 13 000foroneinexcellentconditionand 9 000foroneinaverageconditionDeterminingtheconditionofJane scarhasacostandtheresultsareuncertainTomcannotverifythatJane sMiataissuperiorTombuysanotherMiatafor 8 000 Jane sisunsold SurplusLossandAsymmetricInformation Tom slossis 1 000Pays 8 000andhasagainof 1 000Tom slossfrombuyinganaveragecarinsteadofJane s 13 000 11 000 2 000Tom snetlossis 1 000Jane slossfromlosingTomasacustomeris 1 000Totallossis 2 000 TheLemonsModel Peoplewhohavebelowaveragecars lemons aremorelikelytowanttosellthemBuyersknowthatbelowaveragecarsarelikelytobeonthemarketandlowertheirreservationpricesGoodqualitycarsarewithdrawnfromthemarketAveragequalitydecreasesfurtherandreservationpricesdecreaseagainThelemonsmodelsaysthatasymmetricinformationtendstoreducetheaveragequalityofgoodsforsale YourAunt sCar Yourauntoffersyouher4 yearoldAccordTheaskingpriceof 10 000isthebluebookvalueYoubelievethecarisingoodconditionBluebookvalueistheequilibriumpriceforbelowaveragecarsYoushouldbuythecarfor 10 000ItisinbetterconditionthantheaverageAccordofthesamevintageandmileage Na veBuyer Twokindsofcars goodcarsandlemonsOwnersknowwhatkindtheyhaveBuyerscan tdetermineacar squalityBuyersareriskneutralWhatwouldthebuyerofferforausedcar Expectedvalueofacaris 0 90 10 000 0 10 6 000 9 600Thebuyergetsalemon CredibilityProblem PartiesgainiftheyfindawaytocommunicateinformationtruthfullyIfJanecanconvinceTomherMiataisinexcellentcondition TomwillbuyStatementsarenotcredibleJaneoffersTomasix monthwarrantyonallcardefectsatthetimeofpurchaseAwarrantyforalemonwouldcostmorethantheeconomicsurplusgainedOnlysellersofgoodqualitycarswouldofferthewarranty TheCostly to FakePrinciple Tocommunicateinformationcredibly asignalmustbecostlyordifficulttofakeSellershaveanincentivetoexaggeratethequalityoftheirproductBuyersvalueobjectiveinformationaboutquality CostlySignals TelevisionadvertisingisexpensiveInprintadvertising AsseenonTV signalsacompany scommitmenttoitsproductPotentialsignalofqualityEducationalinstitutions brandsandstudents gradessignalqualityAnA studentfromMITismorelikelytobeofferedajobthanaCstudentfromanaverageacademicinstitution ConspicuousConsumption ChoosealawyerLawyerAwearsinexpensivesuitsanddrivesa10 yearoldDodgeNeonLawyerBwearscustom tailoredsuitsanddrivesanewBMW745iNootherinformationisavailableConspicuousconsumptionsignalssuccessChooseLawyerB andpassonBenMatlock StatisticalDiscrimination StatisticaldiscriminationusesgroupcharacteristicstoinferindividualcharacteristicsCanbeappliedtopeopleaswellastogoodsandservicesResultsfromobserveddifferencesbetweengroupsExampleThiscandidateforemploymentisinherlatetwentiesWomenhavebabiesintheirlatetwentiesThiscandidatewillhaveababyinthenextfewyearsHighcostcomparedtoothercandidates DangerousDrivers Menunder25yearsofagepaymorethanotherdriversforautoinsuranceExpectedcostofinsuringadriverdependstheprobabilityandsizeofclaimsIndividualassessmentsarenotpossibleRatesarebasedondemographicgroupsandtheclaimhistoryofthosegroupsIndividualratesareadjustedupwardasmoreinformationbecomesavailable AdverseSelection AdverseselectionoccursbecauseinsurancetendstobepurchasedmorebythosewhoaremostcostlyforcompaniestoinsureInsuranceismostvaluabletothosewithmanyclaimsAdverseselectionincreasesinsurancepremiumsReducesattractivenessofinsurancetolow riskcustomers Best insuranceriskcustomersoptoutRatesincreaseRepeat MoralHazard MoralhazardisthetendencyofpeopletoexpendlesseffortprotectinginsuredgoodsPeopletakemoreriskwithinsuredgoodsoractivitiesDeductiblesgivepolicyholdersanincentivetobemorecautiousSupposeacarownerhasa 1 000deductiblepolicyTheownerpaysthefirst 1 000ofeachclaimStrongincentivetoavoidaccidentsClaimslessthan 1 000arenotreportedInsurancepremiumsgodown DisappearingPoliticalDiscourse DisappearingpoliticaldiscoursetheoryholdsthatpoliticianswhosupportapolicywillremainsilenttoavoidbeingmisunderstoodOpposingthedeathpenaltycouldbeinterpretedvyvotersasbeingsoftoncrimeNonecessaryrelationshipbetweenthetwoAssumesvotersimplicitlyassignapositiontoapoliticianwhohasnotmadepublicstatements PoliticiansandtheDeathPenalty ArgumentsagainstthedeathpenaltyExpensiverelativetolifeinprisonwithoutparoleIrreversibleforpeoplelaterfoundinnocentDoesnotdetercapitalcrimesPoliticiansavoidtakingapublicpositiononcapitalpunishment PoliticiansandtheDeathPenalty VoterswantpoliticiansaretoughoncrimeBroaderissuethanthedeathpenaltyTwogroupsofpoliticians toughoncrimeandsoftoncrimeVotersuseinformationaboutapolitician svi