复旦大学本科微观经济学assymm.ppt

AsymmetricInformation,Maintopics,problemsduetoasymmetricinformationresponsetoadverseselectionhowignoranceaboutqualitydrivesouthigh-qualitygoodspricediscriminationduetofalsebeliefsaboutqualitymarketpowerfrompriceignoranceproblemsarisingfromignorancewhenhiring,Problemsduetoasymmetricinformation,ifbothpartiestoatransactionhavelimitedinfo,neitherhasanadvantageasymmetricinfoleadstoopportunism,wherebyinformedpersonbenefitsatexpenseofthosewithlessinfo,Typesofopportunisticbehavior,adverseselectionmoralhazard,Adverseselection,opportunismcharacterizedbyaninformedpersonsbenefitingtrading(contracting)withlessinformedpersonwhodoesnotknowaboutanunobservedcharacteristicoftheinformedpersonpeoplewhobuylifeinsuranceknowmoreabouttheirownhealththandoestheinsurancecompany,Adverseselectionmarketfailure,reducessizeofamarket(possiblyeliminatingit)example:fewolderpeopleregardlessoftheirhealthbuytermlifeinsurancebecauseratesareextremelyhighbecauseofadverseselection,Moralhazard,opportunismcharacterizedbyaninformedpersontakingadvantageofaless-informedpersonthroughanunobservedactionexamplessleezeballsellsyouswamplandinFloridaemployeeshirksifnotmonitoredbyemployer,Moralhazardnotnecessarilyharmful,pregnantwomenwithhealthinsurancemakemoreprenataldoctorvisitsextracostbadforinsurancefirms,butsocietybenefitsfromhealthierwomenandbabies,Responsestoadverseselection,mainmethodsforsolvingadverseselectionproblemsaretorestrictopportunisticbehaviorequalizeinformation,Restrictopportunisticbehavior,universalcoverage:provideinsurancetoallemployeesofafirmthusbothhealthyandunhealthypeoplearecoveredfirmbuysmedicalinsuranceatalowercostperpersonthanworkerscouldobtainontheirown(whererelativelymoreunhealthyindividualsbuyinsurance),Meansofequalizinginformation,screeningactiontakenbyanuninformedpersontodetermineinfopossessedbyinformedpeoplebuyertestdrivesmanyusedcarssignalingactiontakenbyaninformedpersontosendinformationtoaless-informedpersonfirmdistributesafavorablereportonitsproductbyanindependenttestingagencytoproveitsqualityishigh,Howignoranceaboutqualitydrivesouthigh-qualitygoods,buyercannotjudgeaproductsqualitybeforepurchasingitlow-qualitycarslemonsmaydrivehighqualityproductsoutofthemarket(Akerlof)ownersoflemonsaremorelikelytoselltheircars,leadingtoadverseselection,Lemonsmarketbuyers,manypotentialbuyersforusedcarsallarewillingtopay$1,000foralemon$2,000foragoodusedcar,Lemonsmarketsellers,ownerswillingtosellupto1,000lemons1,000goodusedcarsreservationpriceofowners(lowestpriceatwhichtheyllselltheircars)$750forlemons$1,250or$1,750forgoodcars,Twopossibleequilibrium,allcarssellataverageprice,$1,500(sellersofgoodcarsareimplicitlysubsidizingsellersoflemons)onlylemonssellforapriceequaltothevaluethatbuyersplaceonlemons(baddrivesoutgood),Valuetosellersofgoodcarsis$1,250,sellerswillingtoselltheircarsataverageprice($1,500)equilibriumprice$1,500inbothmarketslemonsmarketequilibrium:f,intersectionofSLandD*goodmarketequilibrium:F,intersectionofS1andD*asymmetricinformationdoesnotcauseanefficiencyproblem,buthasequityimplications,MarketsforLemons,MarketsforGoodCars,Valuetosellersofgoodcarsis$1,750,lemonsdrivegoodcarsoutofmarketbuyersknowthatonlycarstheycanbuyat$1,750isalemonlemonssellfor$1,000:e,intersectionofSLandDLequilibriumisinefficient:highqualitycarsremaininhandsofpeoplewhovaluethemthandopotentialbuyers,Lemonsmarketwithvariablequality,manyfirmscanvaryqualityoftheirproductsifconsumerscannotidentifyqualityallgoodssellatsamepriceraisingyourqualityraisesaveragepriceofallfirmsinadequateincentivetoproducehighqualitysocialvalueofraisingthequalityisgreaterthantheprivatevalue,Limitinglemons,lawstopreventopportunismconsumerscreeningthird-partycomparisonsstandardsandcertificationstandard:metricorscaleforevaluatingthequalityofaparticularproduct(e.g.,R-valueofinsulation)certification:reportthataparticularproductmeetsorexceedsagivenstandardlevelsignalingbyfirmsguaranteesandwarrantiesbrandname,Pricediscriminationduetofalsebeliefsaboutquality,noisymonopolymultiplebrandnamesrefrigeratorsAmanaandKenmoreWhirlpoolandKenmorecarsFordTaurus&MercurySableToyotaCamry&LexusES300DodgeColt,MitsubishiMirage,PlymouthColt,&EagleSummitBentleyBrookland($152,400)&Rolls-RoyceSilverSpurIII($178,200),Priceignorancemarketpower,limitedinformationaboutpriceleadstomarketpowerconsumerswhodonotknowthataproductcanbeboughtforlesselsewherebuyfromhigh-pricestores,Tourist-trapmodel,manysouvenirshopsguidebooktellsdistributionofpricescoststouristcintimeandexpensestovisitashopandcheckpriceorbuyifprice=p,costsp+ciftouristbuysfromfirststorep+2ciftouristbuysfromsecondstore,Isacompetitivepricecharged?,Monopolyprice,Problemsarisingfromignorancewhenhiring,asymmetricinformationcreatesproblemsinlabormarketsworkersignalingandfirmscreeningmayreduceproblems,Cheaptalk,cheaptalk:unsubstantiatedclaimsorstatementspeopleusecheaptalktodistinguishthemselvesortheirattributesatlowcost,Educationasasignal,collegeeducationcouldpaybecauseitprovidesvaluabletraining,oritservesasasignaltoemployersaboutworkersabilitysupposeeducationdoesntprovidetrainingitsonlyasignal,Example,Twotypesofequilibria,typeofequilibriumdependsonwhetherfirmcandistinguishhigh-abilityworkersfromotherspoolingequilibriumseparatingequilibrium,Poolingequilibrium,Separatingequilibrium,supposehigh-abilityworkerscangetadegreeatcostofctoattendcollegelow-abilityworkerscannotgraduatefromcollegethus,degreeisasignalofabilityoutcomeisaseparatingequilibrium:onetypeofpeopletakeactions(sendasignal)thatallowthemtobedifferentiatedfromothertypesofpeoplehigh-abilityworkersgetwhlow-abilityworkersgetwl,Isseparatingequilibriumpossible?,Ispooling