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首页 通过数字思考经济 Super Crunchers,Why Thinking by Number…

通过数字思考经济 Super Crunchers,Why Thinking by Numbers Is the New Way to Be Smart.pdf

通过数字思考经济 Super Crunchers,Why Th…

上传者: bravegambler 2012-12-16 评分 0 0 0 0 0 0 暂无简介 简介 举报

简介:本文档为《通过数字思考经济 Super Crunchers,Why Thinking by Numbers Is the New Way to Be Smartpdf》,可适用于经济金融领域,主题内容包含us$Canada$WhywouldacasinotrytostopyoufromlosingHowcanamathematicalformulaf符等。

us$Canada$WhywouldacasinotrytostopyoufromlosingHowcanamathematicalformulafindyourfuturespouseWouldyouknowifstatisticalanalysisblackballedyoufromajobyouwantedSUPERCRUNCHERSWHYTHINKINGBYNUMBERSIsTHENEWWAYTOBESMARTToday,numbercrunchingaffectsyourlifeinwaysyoumightneverimagineInthislivelyandgroundbreakingnewbook,economistIanAyresshowshowtoday'sbestandbrightestorganizationsareanalyzingmassivedatabasesatlightningspeedtoprovidegreaterinsightsintohumanbehaviorTheyaretheSuperCrunchersFromInternetsiteslikeGoogleandAmazonthatknowyourtastesbetterthanyoudo,toaphysician'sdiagnosisandyourchild'seducation,toboardroomsandgovernmentagencies,thisnewbreedofdecisionmakersiscallingtheshotsAndtheyaredeliveringstaggeringlyaccurateresultsHowcanafootballcoachevaluateaplayerwithouteverseeinghimplayWanttoknowwhetherthepriceofanairlineticketwillgoupordownbeforeyoubuyHowcanaformulaoutpredictwineexpertsindeterminingthebestvintagesSupercrunchershavetheanswersInthisbravenewworldofequationversusexpertise,Ayresshowsusthebenefitsandrisks,wholosesandwhowins,andhowsupercrunchingcanbeusedtohelp,notmanipulate,us(continuedonbackflap)(continuedfromfrontflap)GonearethedaysofrelyingsolelyonintuitiontomakedecisionsNobusinessperson,consumer,orstudentwhowantstostayaheadofthecurveshouldmakeanotherkeystrokewithoutreadingSuperCrunchersIANAYRES,aneconometricianandlawyer,istheWilliamKTownsendProfessoratYaleLawSchoolandaprofessoratYale'sSchoolofManagementHeisaregularcommentatoronpublicradio'sMarketplaceandacolumnistforForbesmagazineHeiscurrentlytheeditoroftheJournalofLaw,Economics,andOrganizationandhaswritteneightbooksandmorethanahundredarticlesJacketdesignbyTomMcKevenyVisitourwebsiteatwwwbantamdellcomBantamBookslUhyThinkingbynumbersIsthenewlUaytoBeSmartIANAYRESBHRTHmBOOKSNEWYORKLONDONTORONTOSYDNEYAUCKLANDSUPERCRUNCHERSABantamBookfSeptemberPublishedbyBamamDellADivisionofRandomHouse,IncNewYork,NewYorkAllrightsreservedCopyrightbyIanAyresBookdesignbyEllenCiprianoBamamBooksisaregisteredtrademarkofRandomHouse,Inc,andthecolophonisatrademarkofRandomHouse,IncLibraryofCongressCataloginginPublicationDataAyres,IanSupercrunchers:whythinkingbynumbersisthenewwaytobesmanfIanAyrespcmIncludesbibliographicalreferencesandindexStatisticsISBN(hardcover)RegressionanalysisStandarddeviationsSampling(Statistics)ITideHAAdcPrimedintheUnitedStatesofAmericaPublishedsimultaneouslyinCanadawwwbamamdellcomBVGconTEnTSIntroduction:TheRiseoftheSuperCrunchersWho'sDoingYourThinkingforYouCreatingYourOwnDatawiththeFlipofaCoinGovernmentbyChanceHowShouldPhysiciansTreatEvidenceBasedMedicineExpertsVersusEquationslOWhyNowAreWeHavingFunYetTheFutureofIntuition(andExpertise)AcknowledgmentsNotesIndexInTRODllCTlonTheRiseoftheSuperCrunchersOrleyAshenfelterreallyloveswine:"Whenagoodredwineages,"hesays,"somethingquitemagicalhappens"YetOrleyisn'tjustobsessedwithhowwinetastesHewantstoknowabouttheforcesbehindgreatandnotsogreatwines"Whenyoubuyagoodredwine,"hesays,"you'realwaysmakinganinvestment,inthesensethatit'sprobablygoingtobebetterlaterAndwhatyou'dliketoknowisnotwhatit'sworthnow,butwhatit'sgoingtobeworthinthefutureEvenifyou'renotgoingtosellitevenifyou'regoingtodrinkitIfyouwanttoknow,'HowmuchpleasureamIgoingtogetbydelayingmygratification'That'sanendlesslyfascinatingtopic"It'satopicthathasconsumedafairamountofhislifeforthelasttwentyfiveyearsInhisdayjob,OrleycrunchesnumbersHeusesstatisticstoextracthiddeninformationfromlargedatasetsAsaneconomistatPrinceton,he's•SUPERCRUNCHERSlookedatthewagesofidenticaltwinstoestimatetheimpactofanextrayearofschoolHe'sestimatedhowmuchstatesvalueastatisticallifebylookingatdifferencesinspeedlimitsForyearsheeditedtheleadingeconomicsjournalintheUnitedStates,theAmericanEconomicReviewAshenfelterisatallmanwithabushymaneofwhitehairandabooming,friendlyvoicethattendstodominatearoomNomilquetoastheHe'sthekindofguywhowouldquicklydisabuseyouofanystereotypeyoumighthavethatnumbercrunchersaremeek,retiringsoulsI'veseenOrleystridearoundaclassroom,guttingthereasoningbehindaseminarpaperwithaffableexuberanceWhenhestartsouthisremarkswithoverthetoppraise,watchoutWhat'sreallygottenDrleyintroubleiscrunchingnumberstoassessthequalityofBoroeauxwinesInsteadofusingthe"swishingandspitting"approachofwineguruslikeRobertParker,Orleyhasusedstatisticstofindoutwhatcharacteristicsofvintageareassociatedwithhigherorlowerauctionprices"It'sreallyanobrainer,"hesaid"Wineisanagriculturalproductdramaticallyaffectedbytheweatherfromyeartoyear"UsingdecadesofweatherdatafromFrance'sBordeauxregion,DrleyfoundthatlowlevelsofharvestrainandhighaveragesummertemperaturesproducethegreatestwinesThestatisticalfitondatafromthroughwasremarkablytightfortheredwinesofBurgundyaswellasBordeauxBordeauxarebestwhenthegrapesareripeandtheirjuiceisconcentratedInyearswhenthesummerisparticularlyhot,grapesgetripe,whichlowerstheiracidityAnd,inyearswhenthereisbelowaveragerainfall,thefruitgetsconcentratedSoit'sinthehotanddryyearsthatyoutendtogetthelegendaryvintagesRipegrapesmakesupple(lowacid)winesConcentratedgrapesmakefullbodiedwinesHe'shadthetemeritytoreducehistheorytoaformula:Winequality=winterrainfallaveragegrowingseasontemperatureharvestrainfallINTRODUCTION•That'srightBypluggingtheweatherstatisticsforanyyearintothisequation,AshenfeltercanpredictthegeneralqualityofanyvintageWithaslightlyfancierequation,hecanmakemoreprecisepredictionsforthevintagequalityatmorethanChateaus"Itmayseemabitmathematical,"heacknowledges,"butthisisexactlythewaytheFrenchrankedtheirvineyardsbackinthefamousclassifications"TraditionalwinecriticshavenotembracedAshenfelter'sdatadrivenpredictionsBritain'sWInemagazinesaid"theformula'sselfevidentsillinessinvites}disrespect"WilliamSokolin,aNewYorkwinemerchant,saidtheBordeauxwineindustry'sviewofAshenfelter'sworkranges"somewherebetweenviolentandhysterical"Attimes,he'sbeenscornedbytrademembersWhenAshenfeltergaveawinepresentationatChristie'sWineDepartment,dealersinthebackopenlyhissedathispresentationMaybetheworld'smostinfluentialwinewriter(andpublisherofTheWIneAdvocate),RobertParker,colorfullycalledAshenfelter"anabsolutetotalsham"EventhoughAshenfelterisoneofthemostrespectedquantitativeeconomistsintheworld,toParkerhisapproach"isreallyaNeanderthalwayoflookingatwineIt'ssoabsurdastobelaughable"Parkerdismissesthepossibilitythatamathematicalequationcouldhelpidentifywinesthatactuallytastegood:''I'dhatetobeinvitedtohishousetodrinkwine"ParkersaysAshenfelter"isratherlikeamoviecriticwhonevergoestoseethemoviebuttellsyouhowgooditisbasedontheactorsandthedirector"ParkerhasapointJustasit'smoreaccuratetoseethemovie,shouldn'titbemoreaccuratetoactuallytastethewineThere'sjustonecatch:formonthsandmonthsthereisnowinetotasteBordeauxandBurgundiesspendeighteentotwentyfourmonthsinoakcasksbeforetheyaresetasideforaginginbottlesExperts,likeParker,havetowaitfourmonthsjusttohaveafirsttasteafterthewineisplacedinbarrelsAndeventhenit'saratherfoul,fermentingmixtureIt'snotclearthattastingthisundrinkableearlywinegivestastersvery•SUPERCRUNCHERSaccurateinformationaboutthewine'sfuturequalityForexample,BruceKaiser,formerdirectorofthewinedepartmentatauctioneerButterfieldButterfield,hasclaimed,"Youngwinesarechangingsoquicklythatnoone,andImeannoone,canreallyevaluateavintageatallaccuratelybytasteuntilitisatleasttenyearsold,perhapsolder"Insharpcontrast,OrleycrunchesnumberstofindthehistoricalrelationshipbetweenweatherandpriceThat'showhefoundoutthateachcentimeterofwinterraintendstoraisetheexpectedpricedollarsOfcourse,it'sonlyatendencyButnumbercrunchingletsOrleypredictthefuturequalityofavintageassoonasthegrapesareharvestedmonthsbeforeeventhefirstbarreltasteandyearsbeforethewineissoldInaworldwherewinefuturesareactivelytraded,Ashenfelter'spredictionsgivewinecollectorsahugeleguponthecompetitionAshenfelterstartedpublishinghispredictionsinthelateeightiesinasemiannualnewslettercalledLiquidAssetsHeadvertisedthenewsletteratfirstwithsmalladsinWineSpectator,andslowlybuiltabaseofaboutsubscribersThesubscriberswereageographicallydiverselotofmillionairesandwinebuffsmostlyconfinedtothesmallgroupofwinecollectorswhowerecomfortablewitheconometrictechniquesThenewsletter'ssubscriptionbasewasjustafractionofthe,peoplewhoplunkeddown$ayearforRobertParker'snewsletterTheWineAdvocateAshenfelter'sideasreachedamuchlargeraudienceinearlywhentheNewYorkTimespublishedafrontpagearticleabouthisnewpredictionmachineOrleyopenlycriticizedParker'sassessmentoftheBordeauxParkerhadratedthe'sas"verygoodandsometimesexceptional"AshenfelterdisagreedHefeltthatthebelowaveragegrowingseasontemperatureandtheaboveaverageharvestrainfalldoomedthisvintagetomediocrityYettherealbombshellinthearticleconcernedOrley'spredictionabouttheBordeauxWhilethesewineswerebarelythreemonthsinthecaskandhadyettoevenbetastedbycritics,Orleypredictedthattheywouldbe"thewineofthecentury"HeguaranteedthattheyINTRODUCTION•wouldbe"stunninglygood"Onhisscale,ifthegreatBordeauxwere,thentheBordeauxwereawhoppingOrleybrazenlypredictedthattheywould"sellforashighapriceasanywinemadeinthelastthirtyfiveyears"ThewinecriticswereincensedParkernowcharacterizedAshenfelter'squantitativeestimatesas"ludicrousandabsurd"Sokolinsaidthereactionwasamixtureof"furyandfearHe'sreallyupsetalotofpeople"WithinafewyearsWineSpectatorrefusedtopublishanymoreadsforhis(oranyother)newsletterThetraditionalexpertscircledthewagonsandtriedtodiscreditbothOrleyandhismet~odologyHismethodologywasflawed,theysaid,becauseitcouldn'tpredicttheexactfuturepriceForexample,ThomasMatthews,thetastingdirectorofWineSpectator,complainedthatAshenfelter'spricepredictions"wereexactlytrueonlythreetimesinthetwentysevenvintages"EventhoughOrley's"formulawasspecificallydesignedtofitpricedata"his"predictedpricesarebothunderandovertheactualprices"However,tostatisticians(andtoanyoneelsewhothinksaboutitforamoment),havingpredictionsthataresometimeshighandsometimeslowisagoodthingit'sthesignofanunbiasedestimateInfact,OrleyshowedthatParker'sinitialratingsofvintageshadbeensystematicallybiasedupwardMoreoftenthannotParkerhadtodowngradehisinitialrankingsInOrleywentevenfurtheroutonalimbAfterdeclaringthevintageofthecentury,thedatatoldhimthatwasgoingtobeevenbetterAndhesaidsoInretrospectwecannowseethatLiquidAssets'predictionshavebeenastonishinglyaccurateThe'sturnedouttobeatrulyexcellentvintageandthe'swereevenbetterHowcanitbethatyou'dhavetwo"vintagesofthecentury"intwoconsecutiveyearsItturnsoutthatsincetherehasn'tbeenayearwithbelowaveragegrowingseasontemperatureTheweatherinFrancehasbeenbalmyformorethantwodecadesAconvenienttruthforwineloversisthatit'sbeenagreattimetogrowtrulysuppleBordeauxThetraditionalexpertsarenowpayingalotmoreattentiontothe•SUPERCRUNCHERSweatherWhilemanyofthemhaveneverpubliclyacknowledgedthepowerofOrley'spredictions,theirownpredictionsnowcorrespondmuchmorecloselytohissimpleequationresultsOrleystillmaintainshiswebsite,wwwliquidassetcombuthe'sstoppedproducingthenewsletterHesays,"Unlikethepast,thetastersnolongermakeanyhorrendousmistakesFrankly,IkindofkilledmyselfIdon'thaveasmuchvalueaddedanymore"Ashenfelter'sdetractorsseehimasahereticHethreatenstodemystifytheworldofwineHeeschewsfloweryandnonsensical("muscular,""tight,"or"rakish")jargon,andinsteadgivesyoureasonsforhispredictionsTheindustry'sintransigenceisnotjustaboutaesthetics"Thewinedealersandwritersjustdon'twantthepublicinformedtothedegreethatOrleycanprovide,"Kaisernotes"Itstattedwiththe'vintageOrleysaiditwasascam,adreadfulyearsufferingfromalotofrainandnothighenoughtemperaturesButallthewinewritersofthedaywereraving,insistingitwasagreatvintageOrleywasright,butitisn'talwayspopulartoberight"BoththewinedealersandwritershaveavestedinterestinmaintainingtheirinformationalmonopolyonthequalityofwineThedealersusetheperenniallyinflatedinitialrankingsasawaytostabilizepricesAndWineSpectatorandThe~neAdvocatehavemillionsofdollarsatstakeinremainingthedominantarbitersofqualityAsUptonSinclair(andnowAlGore)hassaid,"Itisdifficulttogetamantounderstandsomethingwhenhissalarydependsonhisnotunderstandingit"Thesameholdstrueforwine"Thelivelihoodofalotofpeopledependsonwinedrinkersbelievingthisequationwon'twork,"Orleysays"They'reannoyedbecausesuddenlythey'rekindofobsolete"TherearesomesignsofchangeMichaelBroadbent,chairmanoftheInternationalWineDepartmentatChristie'sinLondon,putsitdiplomatically:"ManythinkOrleyisacrank,andIsupposeheisinmanywaysButIhavefoundthat,yearafteryear,hisideasandhisworkareremarkablyonthemarkWhathedoescanbereallyhelpfultosomeonewantingtobuywine"INTRODUCTION•TheOrleyAshenfelterofBaseballThegrandworldofoenophilesseemsworldsawayfromthegrandstandsofbaseballButinmanyways,AshenfelterwastryingtodoforwinejustwhatwriterBillJamesdidforbaseballInhisannualBaseballAbstracts,JameschallengedthenotionthatbaseballexpertscouldjudgetalentsimplybywatchingaplayerMichaelLewis'sMoneyballshowedthatJameswasbaseball'sheraldofdatadrivendecisionmakingJames'ssimplebutpowerfulthesiswasthatdatabasedanalysisinbaseballwassuperiortoobservationalexpertise:ThenakedeyewasinadequateforlearningwhatyouneedtoknowtoevaluateplayersThinkaboutitOneabsolutelycannottell,bywatching,thedifferencebetweenahitterandahitterThedifferenceisonehiteverytwoweeksIfyouseebothgamesa'year,thereisapercentchancethatthehitterwillhavemorehitsthanthehitterThedifferencebetweenagoodhitterandaveragehitterissimplynotvisibleitisamatterofrecordLikeAshenfelter,JamesbelievedinformulasHesaid,"Ahittershouldbemeasuredbyhissuccessinthatwhichheistryingtodo,andthatwhichheistryingtodoiscreateruns"SoJameswentoutandcreatedanewformulatobettermeasureahitter'scontributiontorunscreated:RunsCreated=(HitsWalks)xTotalBasesf(AtBatsWalks)Thisequationputmuchmoreemphasisonaplayer'sonbasepercentageandespeciallygiveshigherratingstothoseplayerswhotendtowalkmoreoftenJames'snumbercrunchingapproachwasparticularanathematoscoutsIfwinecriticslikeRobertParkerlivebytheir•SUPERCRUNCHERStasteandsmell,thenscoutsliveanddiebytheireyesThat'stheirvalueaddedAsdescribedbyLewis:Inthescouts'view,youfoundbigleagueballplayersbydrivingsixtythousandmiles,stayinginahundredcrappymotels,andeatingGodknowshowmanymealsatDenny'sallsoyoucouldwatchhighschoolandcollegebaseballgamesinsideoffourmonths,ofwhichwerecompletelymeaninglesstoyouYouwouldwalkintotheballpark,findaseatonthealuminumplankinthefourthrowdirectlybehindthecatcherandseesomethingnooneelsehadseenatleastnoonewhoknewthemeaningofitYouonlyhadtoseehimonce"Ifyouseeitonce,it'sthere"ThescoutsandwinecriticslikeRobertParkerhavemoreincommonthansimplyapenchantforspittingJustasParkerbelievesthathecanassessthequalityofaChateau'svintagebasedonasingletaste,baseballscoutsbelievetheycanassessthequalityofthehighschoolprospectbasedonasingleviewingInbothcontexts,peoplearetryingtopredictthemarketvalueofuntestedandimmatureproducts,whethertheybegrapesorbaseballplayersAndinbothcontexts,thecentraldisputeiswhethertorelyonobservationalexpertiseorquantitativedataLikewinecritics,baseballscoutsoftenresorttononfalsifiableeuphemisms,suchas"He'sarealplayer,"or"He'satoolsguy"InMoneyball,theconflictbetweendataandtraditionalexpertisecametoaheadinwhenOaklandNsgeneralmanagerBillyBeanewantedtodraftJeremyBrownBeanehadreadJamesanddecidedhewasgoingtodraftbasedonhardnumbersBeanelovedJeremyBrownbecausehehadwalkedmorefrequentlythananyothercollegeplayerThescoutshatedhimbecausehewas,well,fatIfhetriedtorunincorduroys,anNsscoutsneered,"he'dstartafire"ThescoutsthoughttherewasnowaythatsomeonewithhisbodycouldplaymajorleagueballBeanecouldn'tcarelesshowaplayerlookedHisdraftingmantrawas"We'renotsellingjeans"BeanejustwantedtowingamesTheINTRODUCTION•scoutsseemtobewrongBrownhasprogressedfasterthananyoneelsetheifsdraftedthatyearInSeptember,hewascalledupforhismajorleaguedebutwiththeifsandbatted(withanonbasepercentageof)TherearestrikingparallelsbetweenthewaysthatAshenfelterandJamesoriginallytriedtodisseminatetheirnumbercrunchingresultsJustlikeAshenfelter,Jamesbeganbyplacingsmalladsforhisfirstnewsletter,BaseballAbstr

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