2.4.3.2 Ukufaniswa

Ukuqondanisa ukudala iziqhathaniso muhle sisusa amacala.

iziqhathaniso Fair kungavela noma kwenziwa ucwaningo randomized elawulwa noma ukuhlolwa yemvelo. Kodwa, kunezimo eziningi lapho ungakwazi ungagijimi ukuhlola ekahle kanye nemvelo akanikezanga sokuhlolwa yemvelo. Kulezi izilungiselelo, indlela engcono ukudala isiqhathaniso fair is afanayo. Ngo lelihambisana, umcwaningi ibukeka ngokusebenzisa idatha non-yokulinga ukudala ngababili abantu ezithi azifane ngaphandle kokuthi amukele ukwelashwa kanye nalowo abuzange. In the inqubo lelihambisana, abacwaningi empeleni izihlahla; okungukuthi, ukulahla amacala lapho kukhona akunakuqhathaniswa ezisobala. Ngakho, le ndlela yayiyobizwa more esibizwa ngokunembile elimetjhako-and-izihlahla, kodwa mina ngizobe anamathele ethemini bendabuko: elihamelanayo.

A isibonelo esihle amandla amasu ne massive non-yokulinga imithombo idatha nemnyaka zivela ucwaningo ukuziphatha kwabathengi by Liran Einav kanye nozakwabo (2015) . Einav kanye nozakwabo babenesithakazelo indali ezenzeka eBay, futhi ngo echaza umsebenzi wabo, mina ngizobe sigxile esicini esisodwa esithinta ngokuyinhloko: umphumela we auction kokuqala intengo endalini imiphumela, ezifana intengo ukudayiswa noma ematfuba ukudayiswa.

Indlela iwubuntwana kakhulu ukuphendula umbuzo mayelana nomphumela we starting intengo intengo ukudayiswa bekuyoba okubaluleke kangakanani ukuhlala umane ukubala amanani lokugcina indali nge ezahlukene kuqalwa amanani. Le ndlela kwakuyoba into enhle uma ufuna ukubikezela intengo ukudayiswa item kulokho wayebekwe eBay nge inikezwe starting price. Kodwa, uma umbuzo wakho yilokho umphumela wokuqala intengo imiphumela emakethe le ndlela ngeke isebenze ngoba kusekelwe iziqhathaniso fair; indali nge ephansi starting amanani ingase ihluke kakhulu kuleyo indali nge starting amanani ephakeme (isib, bangase babe yezinhlobo ezahlukene izimpahla noma zihlanganisa izinhlobo ezahlukene nabathengisi).

Uma ukhathazekile kakade mayelana iziqhathaniso ukujabulisa, ungase weqa ndlela kuwubuwula futhi kuyisidala ucabangele egijima sokuhlolwa ensimini lapho wena babekuthengisa othize into bathi, a club-nge igalofu isethi esimisiwe endalini nemingcele-ngithi, lokuthumela free, endalini evulekile for amasonto amabili, njll-kodwa ngezikhathi setha amanani ukuqala. Ngokuqhathanisa umphumela outcomes emakethe, lokhu field wayenikelelani yokukala esicacile emphumeleni kokuqala intengo intengo ukudayiswa. Kodwa, leso silinganiso kuyomane zisebenza komunye umkhiqizo othize bese usetha of endalini nemingcele. Le miphumela ingase ibe khona ehlukile, isibonelo, izinhlobo ezahlukene imikhiqizo. Ngaphandle theory eqinile, kuba nzima extrapolate kusuka kule experiment single uhla oluphelele ucwaningo ezingase eziye run. Ngaphezu kwalokho, ucwaningo mkhakha ngokwanele eqolo ukuthi bekuyoba infeasible ukugijima ngokwanele kubo kuze kufinyelele amboze yonke ipharamitha ye isikhala imikhiqizo kanye endalini izinhlobo.

Ngokungafani kusondela ukuzikhohlisa kanye nendlela yokulinga, Einav kanye nozakwabo izinto ngendlela sesithathu: elihamelanayo. The trick main amasu abo ukuthola izinto ezifanayo kukubuka ensimini kakade kwenzeka on eBay. Ngokwesibonelo, Figure 2.6 siveza okunye 31 uhlu nse igalofu club-a Taylormade sikaphalafini 09 Driver-kuthengiswa by nse seller- "budgetgolfer". Nokho, lokhu kufakwa ohlwini anezici ukuhluka. Eleven kubo zinikeza umshayeli ngentengo elimisiwe $ 124,99, kanti ezinye ezingu-20 kukhona indali izinsuku ezahlukene ekupheleni. Futhi, uhlu babe lokuthumela izimali ezahlukene, kungaba $ 7.99 noma $ 9.99. Ngamanye amazwi, kunjengokungathi "budgetgolfer" iyasebenza ucwaningo abacwaningi.

Uhlu we Taylormade sikaphalafini 09 Driver kuthengiswa by "budgetgolfer" kukhona esinye sezibonelo zezindlela iqoqo ifaniswe uhlu, lapho esiqondile into eyodwa ithengiswa nge ngqo nomthengisi efanayo kodwa isikhathi ngasinye ezinezici ukuhluka. Ngaphakathi izingodo ezinkulu eBay kukhona ngokoqobo namakhulu ezinkulungwane lishona ifaniswe ezihilela izigidi uhlu. Ngakho, kunokuba ngokuqhathanisa amanani lokugcina yonke indali ngaphakathi enikeziwe starting price, Einav kanye nozakwabo iziqhathanise ngaphakathi lishona abafanelana. Ukuze ukuhlanganisa imiphumela kusukela iziqhathaniso ngaphakathi kwalezi ngamakhulu ezinkulungwane lishona ifaniswe, Einav kanye nozakwabo kabusha ukuveza intengo starting kanye amanani yokugcina ngokwemigomo ye-reference value ngakunye (isib, ukudayiswa amanani kwayo ngokwesilinganiso). Ngokwesibonelo, uma Taylormade sikaphalafini 09 Driver inenani inkomba $ 100 (okusekelwe yokuthengisa ayo), khona-ke ngentengo eziqala of $ 10 laliyodluliselwa uzwakalise njengoba 0.1 kanye amanani yokugcina $ 120 laliyodluliselwa wezwakalisa njengoba 1.2.

Figure 2.6: Isibonelo isethi abafanelana. Lona ngqo efanayo igalofu club (a Taylormade sikaphalafini 09 Driver) kuthengiswa by ngqo umuntu ofanayo ( "budgetgolfer"), kodwa ezinye zazo yokuthengisa zazenziwa izimo ezahlukene (isib, ezahlukene starting price). Figure othathwe Einav et al. (2015) .

Khumbula ukuthi Einav kanye nozakwabo babenesithakazelo umphumela we intengo ekuqaleni kwesando imiphumela. Okokuqala, usebenzisa ekuhlehleni komugqa balinganisela ukuthi amanani starting ephakeme wehlise ematfuba ukudayiswa, nokuthi amanani starting ephakeme ukwandisa ukudayiswa amanani yokugcina, okunemibandela on ukudayiswa ezenzeka. Ngamandla abo, laba tilinganiso-iziphi alinganiswe yonke imikhiqizo kanye lokucabanga nobuhlobo lwento phakathi starting price nolokugcina lemiselwe akuzona zonke ukuthi ezithakazelisayo. Kodwa, Einav kanye nozakwabo futhi usebenzise ubukhulu omkhulu kwemininingwane yabo ukulinganisa ezihlukahlukene okutholakele kucashile. Okokuqala, Einav kanye nozakwabo wenza lezi tilinganiso ngokwehlukana izinto ngamanani ahlukene futhi ngaphandle kokusebenzisa ekuhlehleni komugqa. Bathola ukuthi ngenkathi ubuhlobo phakathi intengo isiqalo kanye ematfuba ukudayiswa lwento, ubuhlobo phakathi starting price and intengo edayise ngayo ngokucacile non-eqondile (Figure 2.7). Ikakhulu, ukuqala amanani phakathi 0.05 no 0.85, intengo starting has nomthelela omncane kakhulu intengo ukudayiswa, sokuthi yaqedwa ezingaphendulwanga ukuhlaziya ukuthi wayecabanga nobuhlobo lwento.

Umfanekiso 2.7: Ubudlelwane phakathi endalini isiqalo intengo kanye ematfuba ukudayiswa (panel kwesokunxele) kanye abebhadalwa (panel kwesokudla). Kukhona cishe ubuhlobo lwento phakathi price isiqalo kanye ematfuba ukudayiswa, kodwa kukhona ubuhlobo non-eqondile phakathi price isiqalo kanye nentengo ukudayiswa; ukuqala amanani phakathi 0.05 no 0.85, intengo starting has nomthelela omncane kakhulu intengo ukudayiswa. Kuzo zombili lezi zimo, ubudlelwano ngokuyisisekelo ezimele into value. Lezi amagrafu zizalane Fig 4a futhi 4b Einav et al. (2015) .

Okwesibili, kunokuba ngokwesilinganiso phezu zonke izinto, Einav kanye nozakwabo futhi sebenzisa ngezinga elikhulu kwemininingwane yabo ukulinganisa umthelela wokuqala lamakamelo mayelana nemikhakha ehlukene 23 lwezinto (isib, Izimpahla isilwane, electronics, kanye nemidlalo nezinto zenkolo) (Figure 2.8). Lezi tilinganiso zibonisa ukuthi ukuze olwehlukanisa more izinto-ezifana intengo nezinto zenkolo-isiqalo kunomphumela encane ematfuba ukudayiswa kanye nomphumela emikhulu yokugcina yokuthengisa intengo. Ngaphezu kwalokho, ngoba izinto ezimbi ezinjengezimpi commodified kakhudlwana njengoba DVD kanye video-intengo isiqalo has cishe namthelela amanani yokugcina. Ngamanye amazwi, okuyisilinganiso sabangu ehlanganisa imiphumela kusuka imikhakha ehlukene 23 lwezinto efihla imininingwane ebalulekile mayelana umehluko phakathi kwalezi zinto.

Umfanekiso 2.8: Ezenye wabonisa ezakhishwa isigaba ngayinye; ichashaza siqinile balinganisela ukuthi zonke izigaba sebehlanganisa ndawonye (Einav et al. 2015, Table 11) . Lezi tilinganiso zibonisa ukuthi ukuze olwehlukanisa more izinto-ezifana nezinto zenkolo-intengo isiqalo kunomphumela encane ematfuba ukudayiswa (x-axis) kanye nomphumela emikhulu yokugcina yokuthengisa intengo (Y-axis).

Ngisho noma ungeyena nesithakazelo ngokukhethekile indali on eBay, kumele ubunyoninco indlela ukuthi Umfanekiso 2.7 Umfanekiso 2.8 sipho a ukuqonda acebile eBay kuka elula eqondile emuva ankho tilinganiso ukuthi lokucabanga ubudlelwano eqondile futhi sihlanganise izigaba eziningi izinto ezahlukene. Lezi tilinganiso olucashile ubonise amandla afanayo e idatha okukhulu; lezi tilinganiso kwakungenakwenzeka ngaphandle isibalo omkhulu nemaresiphi ensimini, okufanele ukuba kwakumangalisa prohibitively ezibizayo.

Yiqiniso, kufanele sibe nesibindzi kancane imiphumela yanoma yimuphi elimetjhako isifundo esithile ngaphezu kokuba thina ubungenza imiphumela: se-eksperimenti engaqhathaniswa. Uma sihlola imiphumela kusuka kunoma iyiphi isifundo elimetjhako, kunezinto ezikhathazayo ezimbili ezibalulekile. Okokuqala, kumele sikhumbule ukuthi singakwazi ukuqinisekisa kuphela iziqhathaniso ukujabulisa ezintweni zazisetshenziselwa elihamelanayo. In imiphumela yabo main, Einav kanye nozakwabo akazange esiqondile ukumadanisa izici ezine: Inombolo seller ID, intwana isigaba, intwana isihloko, umbhalo. Uma izinto zazihlukile ngezindlela ukuthi ayengasetshenziswa okufanayo, ezingaholela ukudala i uqhathanisa ngokungafanele. Ngokwesibonelo, uma "budgetgolfer" ngihlaliswa amanani for Taylormade sikaphalafini 09 Driver ebusika (uma izinduku zegalofu kukhona esingaphansi ethandwa), khona-ke kwakungase kubonakale sengathi ephansi starting amanani kuholele ukwehlisa amanani kokugcina, lapho empeleni lokhu kuyoba mshini zonyaka ukushintshashintsha funa. Ngokuvamile, indlela enhle kakhulu yokuba le nkinga ubonakala uzama izinhlobo eziningi elihamelanayo ezahlukene. Ngokwesibonelo, Einav kanye nozakwabo ukuphinda ucwaningo lwabo lapho lishona ifaniswe zihlanganisa izinto ezisendalini kungakapheli unyaka owodwa, kungakapheli inyanga eyodwa, futhi contemporaneously. Ukwenza isikhathi iwindi baqaphe kunciphisa inani amaqoqo ifaniswe, kodwa kunciphisa ukukhathazeka mayelana ukushintshashintsha ezithile zonyaka. Ngenhlanhla, lapho beshada, bakuthola ukuthi imiphumela kukhona ingashintshile lezi zinguquko in criteria afanayo. In the izincwadi lelihambisana, lolu hlobo of ukukhathazeka is ngokuvamile uzwakalise mayelana observables futhi unobservables, kodwa iphuzu eliyinhloko ngempela abacwaningi kuphela ngokudala iziqhathaniso ukujabulisa izici elisetshenziswa elihamelanayo.

Owesibili ukukhathazeka okukhulu lapho ehumusha imiphumela efanayo iwukuthi bagcina zisebenza idatha abafanelana; they azisebenzi la macala ukuthi alikwazanga abafanelana. Ngokwesibonelo, ngokukhawulela ucwaningo lwabo ukuze izinto ukuthi kwakufanele ukufakwa ohlwini okuningi Einav kanye nozakwabo basuke ngokugxila on nabathengisi professional kanye semi-professional. Ngakho, lapho ehumusha la magama kumelwe sikhumbule ukuthi zisebenza kuphela kule isethi engaphansi eBay.

Ukufaniswa isu esinamandla sokuthola iziqhathaniso fair in datasets ezinkulu. Ukuze ososayensi abaningi social, lelihambisana uzizwa like wesibili best kukubuka, kodwa ukuthi yokuthi kufanele olubukeziwe, kancane. Ukumadanisa idatha okukhulu kungase kube ngcono kunokuba inombolo encane ucwaningo emkhakheni lapho: 1) heterogeneity imiphumela kubalulekile futhi 2) kukhona observables ezinhle okufanayo. Ithebula 2.4 sihlinzekela ezinye izibonelo zendlela kumatanisa ingasetshenziswa nge big imithombo idatha.

Ekuphetheni, tindlelanchubo ukuzikhohlisa kulinganiswa imiphumela esiyimbangela kusukela idatha non-yokulinga ziyingozi. Nokho, amasu ngokwenza tilinganiso esiyimbangela elele kanye Eziqhubekayo kusuka anamandla umpofu, nabacwaningi angathola iziqhathaniso fair ngaphakathi idatha non-zokuhlola. Kukhula njalo-on, big idatha izinhlelo kuthuthukisa ikhono lethu ukuze uwusebenzise kahle izindlela ezimbili ezikhona kwenziwa ucwaningo yemvelo kanye elihamelanayo.