why we make bad decisionsWord文件下载.docx

why we make bad decisionsWord文件下载.docx

《why we make bad decisionsWord文件下载.docx》由会员分享，可在线阅读，更多相关《why we make bad decisionsWord文件下载.docx（10页珍藏版）》请在冰豆网上搜索。

andthevalueofthatgaintous.

1:

18Inasense,whatBernoulliwassayingis, 

ifwecanestimateandmultiplythesetwothings, 

wewillalwaysknowpreciselyhowweshouldbehave.

26Now,thissimpleequation,evenforthoseofyou 

whodon'

tlikeequations,issomethingthatyou'

requiteusedto. 

Here'

sanexample:

ifIweretotellyou,let'

splay 

alittlecointossgame,andI'

mgoingtoflipacoin, 

andifitcomesupheads,I'

mgoingtopayyou10dollars, 

butyouhavetopayfourdollarsfortheprivilegeofplayingwithme, 

mostofyouwouldsay,sure,I'

lltakethatbet.Becauseyouknow 

thattheoddsofyouwinningareonehalf,thegainifyoudois10dollars, 

thatmultipliestofive,andthat'

smorethanI'

mchargingyoutoplay.So,theansweris,yes. 

Thisiswhatstatisticianstechnicallycalladamnfinebet.

2:

03Now,theideaissimplewhenwe'

reapplyingittocointosses, 

butinfact,it'

snotverysimpleineverydaylife. 

Peoplearehorribleatestimatingbothofthesethings, 

andthat'

swhatIwanttotalktoyouabouttoday.

16Therearetwokindsoferrorspeoplemakewhentryingtodecide 

whattherightthingistodo,andthoseare 

errorsinestimatingtheoddsthatthey'

regoingtosucceed, 

anderrorsinestimatingthevalueoftheirownsuccess. 

Now,letmetalkaboutthefirstonefirst. 

Calculatingoddswouldseemtobesomethingrathereasy:

therearesixsidestoadie,twosidestoacoin,52cardsinadeck. 

Youallknowwhatthelikelihoodisofpullingtheaceofspades 

orofflippingaheads. 

Butasitturnsout,thisisnotaveryeasyideatoapply 

ineverydaylife.That'

swhyAmericansspendmore-- 

Ishouldsay,losemore--gamblingthanonallotherformsofentertainmentcombined. 

Thereasonis,thisisn'

thowpeopledoodds.

3:

02Thewaypeoplefigureodds 

requiresthatwefirsttalkabitaboutpigs. 

Now,thequestionI'

mgoingtoputtoyouiswhetheryouthink 

therearemoredogsorpigsonleashes 

observedinanyparticulardayinOxford. 

Andofcourse,youallknowthattheanswerisdogs. 

Andthewaythatyouknowthattheanswerisdogsis 

youquicklyreviewedinmemorythetimes 

you'

veseendogsandpigsonleashes. 

Itwasveryeasytorememberseeingdogs, 

notsoeasytorememberpigs.Andeachoneofyouassumed 

thatifdogsonleashescamemorequicklytoyourmind, 

thendogsonleashesaremoreprobable. 

That'

snotabadruleofthumb,exceptwhenitis.

40So,forexample,here'

sawordpuzzle. 

Aretheremorefour-letterEnglishwords 

withRinthethirdplaceorRinthefirstplace?

Well,youcheckmemoryverybriefly,makeaquickscan, 

andit'

sawfullyeasytosaytoyourself,Ring,Rang,Rung, 

andveryhardtosaytoyourself,Pare,Park:

theycomemoreslowly.Butinfact,therearemanymorewordsintheEnglishlanguage 

withRinthethirdthanthefirstplace. 

ThereasonwordswithRinthethirdplacecomeslowlytoyourmind 

isn'

tbecausethey'

reimprobable,unlikelyorinfrequent. 

It'

sbecausethemindrecallswordsbytheirfirstletter. 

Youkindofshoutoutthesound,S--andthewordcomes. 

slikethedictionary;

it'

shardtolookthingsupbythethirdletter. 

So,thisisanexampleofhowthisideathat 

thequicknesswithwhichthingscometomind 

cangiveyouasenseoftheirprobability--

4:

30howthisideacouldleadyouastray.It'

snotjustpuzzles,though. 

Forexample,whenAmericansareaskedtoestimatetheodds 

thattheywilldieinavarietyofinterestingways-- 

theseareestimatesofnumberofdeathsperyear 

per200millionU.S.citizens. 

Andthesearejustordinarypeoplelikeyourselveswhoareasked 

toguesshowmanypeoplediefromtornado,fireworks,asthma,drowning,etc.Comparethesetotheactualnumbers.

54Now,youseeaveryinterestingpatternhere,whichisfirstofall, 

twothingsarevastlyover-estimated,namelytornadoesandfireworks. 

Twothingsarevastlyunderestimated:

dyingbydrowninganddyingbyasthma.Why?

Whenwasthelasttimethatyoupickedupanewspaper 

andtheheadlinewas,"

BoydiesofAsthma?

"

snotinterestingbecauseit'

ssocommon. 

sveryeasyforallofustobringtomindinstances 

ofnewsstoriesornewsreelswherewe'

veseen 

tornadoesdevastatingcities,orsomepoorschmuck 

who'

sblownhishandsoffwithafireworkontheFourthofJuly. 

Drowningsandasthmadeathsdon'

tgetmuchcoverage. 

Theydon'

tcomequicklytomind,andasaresult, 

wevastlyunderestimatethem.

5:

36Indeed,thisiskindofliketheSesameStreetgame 

of"

Whichthingdoesn'

tbelong?

Andyou'

rerighttosay 

stheswimmingpoolthatdoesn'

tbelong,becausetheswimmingpool 

istheonlythingonthisslidethat'

sactuallyverydangerous. 

Thewaythatmoreofyouarelikelytodiethanthecombination 

ofallthreeoftheothersthatyouseeontheslide.

55Thelotteryisanexcellentexample,ofcourse--anexcellenttest-case 

ofpeople'

sabilitytocomputeprobabilities. 

Andeconomists--forgiveme,forthoseofyouwhoplaythelottery-- 

buteconomists,atleastamongthemselves,refertothelottery 

asastupiditytax,becausetheoddsofgettinganypayoff 

byinvestingyourmoneyinalotteryticket 

areapproximatelyequivalenttoflushingthemoney 

directlydownthetoilet--which,bytheway, 

doesn'

trequirethatyouactuallygotothestoreandbuyanything.

6:

23Whyintheworldwouldanybodyeverplaythelottery?

Well,therearemanyanswers,butoneanswersurelyis, 

weseealotofwinners.Right?

Whenthiscouplewinsthelottery, 

orEdMcMahonshowsupatyourdoorwiththisgiantcheck-- 

howthehelldoyoucashthingsthatsize,Idon'

tknow. 

WeseethisonTV;

wereadaboutitinthepaper. 

Whenwasthelasttimethatyousawextensiveinterviews 

witheverybodywholost?

Indeed,ifwerequiredthattelevisionstationsrun 

a30-secondinterviewwitheachloser 

everytimetheyinterviewawinner,the100millionlosers 

inthelastlotterywouldrequirenine-and-a-halfyears 

ofyourundividedattentionjusttowatchthemsay, 

Me?

Ilost."

"

Now,ifyouwatchnine-and-a-halfyearsoftelevision-- 

nosleep,nopottybreaks--andyousawlossafterlossafterloss,andthenattheendthere'

s30secondsof,"

andIwon,"

thelikelihoodthatyouwouldplaythelotteryisverysmall.

7:

17Look,Icanprovethistoyou:

here'

salittlelottery. 

There'

s10ticketsinthislottery. 

Nineofthemhavebeensoldtotheseindividuals. 

Itcostsyouadollartobuytheticketand,ifyouwin, 

youget20bucks.Isthisagoodbet?

Well,Bernoullitellsusitis. 

Theexpectedvalueofthislotteryistwodollars;

thisisalotteryinwhichyoushouldinvestyourmoney. 

Andmostpeoplesay,"

OK,I'

llplay."

39Now,aslightlydifferentversionofthislottery:

imaginethatthenineticketsareallowned 

byonefatguynamedLeroy. 

Leroyhasninetickets;

there'

soneleft. 

Doyouwantit?

Mostpeoplewon'

tplaythislottery.Now,youcanseetheoddsofwinninghaven'

tchanged, 

butit'

snowfantasticallyeasytoimaginewho'

sgoingtowin. 

seasytoseeLeroygettingthecheck,right?

Youcan'

tsaytoyourself,"

I'

maslikelytowinasanybody,"

becauseyou'

renotaslikelytowinasLeroy. 

Thefactthatallthoseticketsareownedbyoneguy 

changesyourdecisiontoplay, 

eventhoughitdoesnothingwhatsoevertotheodds.

8:

13Now,estimatingodds,asdifficultasitmayseem,isapieceofcake 

comparedtotryingtoestimatevalue:

tryingtosaywhatsomethingisworth,howmuchwe'

llenjoyit, 

howmuchpleasureitwillgiveus. 

Iwanttotalknowabouterrorsinvalue. 

HowmuchisthisBigMacworth?

Isitworth25dollars?

Mostofyouhavetheintuitionthatit'

snot-- 

youwouldn'

tpaythatforit.

37Butinfact,todecidewhetheraBigMacisworth25dollarsrequires 

thatyouaskone,andonlyonequestion,whichis:

WhatelsecanIdowith25dollars?

Ifyou'

veevergottenononeofthoselong-haulflightstoAustralia 

andrealizedthatthey'

renotgoingtoserveyouanyfood, 

butsomebodyintherowinfrontofyouhasjustopened 

theMcDonald'

sbag,andthesmellofgoldenarches 

iswaftingovertheseat,youthink, 

Ican'

tdoanythingelsewiththis25dollarsfor16hours. 

tevensetitonfire--theytookmycigarettelighter!

Suddenly,25dollarsforaBigMacmightbeagooddeal.

9:

10Ontheotherhand,ifyou'

revisitinganunderdevelopedcountry, 

and25dollarsbuysyouagourmetmeal,it'

sexorbitantforaBigMac. 

Whywereyouallsurethattheanswertothequestionwasno, 

beforeI'

deventoldyouanythingaboutthecontext?

BecausemostofyoucomparedthepriceofthisBigMac 

tothepriceyou'

reusedtopaying.Ratherthanasking, 

WhatelsecanIdowithmymoney,"

comparingthisinvestment 

tootherpossibleinvestments,youcomparedtothepast. 

Andthisis