2.4.3.2 Ukutshatisa

Ukutshatisa ukwenza uthelekiso enobulungisa ususa amatyala.

uthelekiso Fair isenokuvela nokuba imifuniselo olungenamkhethe olulawulwayo okanye imifuniselo yendalo. Kodwa ke, kukho iimeko ezininzi apho awunaku kwazi ukucikideka efanelekileyo kunye nohlobo akasinikanga kwelinge yendalo. Kwezi zicwangciso, indlela engcono kukwenza uthelekiso fair nto kuthelekiseka. Xa matching, umphandi ukhangela ngokusebenzisa iinkcukacha ezingezizo zovavanyo ukudala izibini abantu ezifanayo ngaphandle ukuba uye wafumana unyango, omnye u nga. Xa inkqubo matching, abaphandi okunene ukuthenwa; oko kukuthi, ulahle kwiimeko apho kungekho uthelekiso ezicacileyo. Ngoko ke, le ndlela iya ngaphezulu ngokuchanekileyo ngokuba matching-kwaye-ukuthenwa, kodwa ndiza kunamathela kwikota yemveli: ethelekisa.

Umzekelo omhle kwamandla qhinga imithombo yedatha non-zovavanyo oxandileyo kuthelekiseka evela ngophando ukuziphatha kwabathengi yi Liran Einav noogxa (2015) . Einav kunye nabalingane babenomdla kwifkunyeesi kuqhubeka eBay, kwaye echaza umsebenzi wabo, Ndiza kugxininisa omnye umba othile: isiphumo ixabiso ukuqala efandesini kwiziphumo yasesidlangalaleni, ezifana ixabiso intengiso okanye nokulindeleka kwentengiso.

Eyona ndlela abangazi ukuphendula umbuzo malunga nefuthe ixabiso lokuqalisa kwi xabiso intengiso iya kuba ukubala ngokulula ixabiso lokugqibela kwifkunyeesi namaxabiso lokuqalisa ezahlukeneyo. Le ndlela iya kuba ukuba ufuna nje ukuqikelela ixabiso intengiso ethile kuyaziwa ukuba bekhutshiwe kwi eBay kunye ngexabiso Ukuqala elinikiweyo entle. Kodwa ke, ukuba umbuzo wakho yintoni isiphumo ukuqala ixabiso kwiziphumo imarike le ndlela iya kusebenza kuba oko kusekelwe uthelekiso ngokufanelekileyo; kweefandesi ngamaxabiso lokuqalisa aphantsi kunokuba zahluke kwifkunyeesi kunye namaxabiso lokuqalisa ephakamileyo (umzekelo, ukuze abe iintlobo ezahlukeneyo zeempahla okanye iquka iintlobo ezahlukeneyo lwabathengisi).

Ukuba sele unexhala ukwenza uthelekiso ezu, ukuze ukutsiba indlela benendelelo yaye cinga Ndiqhuba lamava entsimini apho uya kuthengisa ngumcimbi-ndithi, iklabhu-ne Galufa iseti esisigxina yefandesi parameters-ndithi, yokuthumela ezamahala, ifandesi evulekileyo iiveki ezimbini, njalo-kodwa randomly okuqingqa amaxabiso ukuqala. Ngokuthelekisa iziphumo onesiphumo emarikeni, le ulingelo zasendle kunikela womlinganiselo ecacileyo kakhulu isiphumo ukuqala ixabiso kwi xabiso lihlile. Kodwa, lomlinganiselo kuya kusebenza kuphela enye imveliso ethile kunye iseti iparameters kwentengiso. Iziphumo kunokuba eyahlukileyo, umzekelo, iindidi ezahlukeneyo iimveliso. Ngaphandle ithiyori ngamandla, kunzima ukuba lwento kule ulingelo enye kuluhlu olupheleleyo eksperimenti kunokwenzeka ukuba abe nako ukubaleka. Ngaphezu koko, amalinge endle eninzi ngokwaneleyo ukuba bekuya kuba infeasible ukubaleka ngokwaneleyo ukusa yokuzunguleza isithuba parameter lonke iimveliso kunye neendidi efandesini.

Ngokuchasene nendlela benendelelo yaye indlela zovavanyo, Einav kunye nabalingane kuthatha indlela wesithathu: ethelekisa. Iqhinga eziphambili yesicwangciso yabo ukuze bafumane izinto ezifanayo imifuniselo endle sele ezenzeka eBay. Umzekelo, Umfanekiso 2.6 ibonisa ezinye kwezi zintlu 31 Kuba kanye kwiklabhu yegalufa-a efanayo Taylormade sokukhuphela 09 Driver-uthengiswe kanye seller- efanayo "budgetgolfer". Nangona kunjalo, ezi zintlu baneempawu ezahlukeneyo kancinane. Elinanye kubo wolenza umqhubi ngexabiso eliqingqiweyo $ 124,99, ngoxa elinye 20 kwifkunyeesi kunye nemihla eziveliswayo. Kwakhona, kwezi zintlu kufuneka imirhumo yokuthumela ezahlukeneyo, nokuba $ 7,99 okanye $ 9,99. Ngamanye amazwi, kuba ngathi 'budgetgolfer "nto imifuniselo ngenxa abaphandi aphilileyo.

Ezi zintlu ze Taylormade sokukhuphela 09 Driver uthengiswe "budgetgolfer" omnye umzekelo iseti etelekiswe we kwizintlu, apho into eyiyo enye uthengiswe nomthengisi kanye okufanayo kodwa ixesha ngalinye ezineempawu ezahlukeneyo kancinane. Phakathi iinkuni exandileyo eBay kukho khulu amawaka iiseti etelekiswe ezibandakanya izigidi kwizintlu. Ngoko ke, kunokuba ngokuthelekisa ixabiso lokugqibela zonke kwifkunyeesi ngaphakathi ixabiso Ukuqala elinikiweyo, Einav noogxa ukwenza uthelekiso phakathi iiseti etelekiswe. Ukuze ukudibanisa iziphumo ezivela uthelekiso phakathi kwezi amakhulu amawaka iiseti etelekiswe, Einav kunye nabalingane ngokutsha ukuvakalisa ixabiso oluqala ixabiso lokugqibela ngokwemiqathango ixabiso reference ngombandela ngamnye (umzekelo, ixabiso layo intengiso avareji). Umzekelo, ukuba Taylormade sokukhuphela 09 umqhubi ixabiso yesalathiso ye $ 100 (ngokusekelwe kwiintengiso ayo), ngoko ke ixabiso loqalo $ 10 bekuya singachazwa njengento 0.1 kunye nexabiso lokugqibela $ 120 iya liboniswa 1.2.

Isazobe 2.6: Umzekelo iseti etelekiswe. Oku ngqo Golf Club efanayo (uMqhubi Taylormade sokukhuphela 09) athengiswa ngumntu kanye okufanayo ( "budgetgolfer"), kodwa ezinye zezi yentengiso zenziwa kwiimeko ezahlukeneyo (umzekelo, ixabiso lokuqala ezahlukeneyo). Bathathwa kwi Einav et al. (2015) .

Khumbula ukuba Einav kunye nabalingane babenomdla isiphumo ixabiso ekuqaleni kwiziphumo efandesini. Okokuqala, usebenzisa i sine baqikelela ukuba amaxabiso lokuqalisa aphezulu ukunciphisa amathuba kwentengiso, nokuba amaxabiso lokuqalisa aphezulu wolandisa ixabiso intengiso lokugqibela, ezinemiqathango phezu intengiso zisenzeka. Bebodwa, ezi uqikelelo-leyo average zonke iimveliso kunye acingele ubudlelwane yomgama phakathi ixabiso lokuqala nelokugqibela neziphumo-a kuphela umdla. Kodwa, Einav kunye nabalingane sebenzisa ubukhulu exandileyo data zabo ukuqikelela iintlobo zophando ngokungangqalanga. Okokuqala, Einav kunye nabo benza ezi noqikelelo ngokwahlukileyo izinto amaxabiso awahlukeneyo ngaphandle kokusebenzisa i sine. Bafumanisa ukuba xa ubudlelwane phakathi ixabiso ekuqaleni kwaye linokuba kwentengiso na engumgca, ulwalamano phakathi kwexabiso okuqalisa kunye nexabiso intengiso ngokucacileyo non-ndanga (Figure 2.7). Ngokukodwa, kuba ukuqala amaxabiso phakathi 0.05 kunye 0.85, ixabiso lokuqala ke kube nempembelelo encinane kakhulu ngexabiso intengiso, yokufunyaniswa ukuba yagqitywa kufakelwe uhlahlelo ndandicinga ulwalamano yomgama.

Isazobe 2.7: Ubudlelwane phakathi ifandesi ekuqaleni ixabiso kwaye linokuba kwentengiso (panel ekhohlo) kunye nexabiso intengiso (yolawulo ekunene). Kukho kuphantse ubudlelwane yomgama phakathi ixabiso ekuqaleni kwaye linokuba sentengiso, kodwa kukho unxulumano non-yomgama phakathi ixabiso ekuqaleni nexabiso intengiso; sokuqalisa amaxabiso phakathi 0.05 kunye 0.85, ixabiso lokuqala ke kube nempembelelo encinane kakhulu ngexabiso lihlile. Kuzo zombini iimeko ubudlelwane, ngabona elizimeleyo yexabiso item. Ezi iigrafu lokuyivelisa Isazobe 4a kunye 4b Einav et al. (2015) .

Okwesibini, kunokuba nama zonke izinto, Einav kunye nabalingane sebenzisa isikali exandileyo data zabo ukuqikelela ifuthe nexabiso ukuqala kumahlelo 23 ezahlukeneyo izinto (umzekelo, impahla yezilwanyana, izinto zombane, kunye ezizizikhumbuzo ezemidlalo) (Figure 2.8). Ezi uqikelelo lubonisa ukuba ngenxa olwahluke kakhulu izinto-ezifana nexabiso ezisisikhumbuzo-START kunempembelelo encinci nokulindeleka intengiso yaye kunempembelelo enkulu phezu ixabiso kwintengiso lokugqibela. Ngokubhekele phaya, kuba izinto-ezifana commodified ngakumbi njengoko iiDVD neevidiyo-ixabiso START phantse akukho nefuthe ixabiso lokugqibela. Ngamanye amazwi, umlinganiselo oludibanisa iziphumo ezivela iindidi 23 ezahlukeneyo izinto ufihla ulwazi olubalulekileyo malunga umahluko phakathi kwezi zinto.

Isazobe 2.8: Iziphumo abonisa uqikelelo ukusuka kudidi ngalunye ngabanye; unotsheluza siqinile Uqikelelo zonke iindidi ukunqanda kunye (Einav et al. 2015, Table 11) . Ezi uqikelelo lubonisa ukuba ngenxa olwahluke kakhulu izinto-ezifana ezizizikhumbuzo-ixabiso ekuqaleni kunempembelelo encinci nokulindeleka intengiso (x-axis) yaye kunempembelelo enkulu phezu ixabiso kwintengiso lokugqibela (y-axis).

Nokuba awunamdla ngokukodwa kwifkunyeesi on eBay, kufuneka ukuba bamhlonele indlela Umboniso 2.7 owuvayo 2.8 nokubonelela ukuqonda ezityebileyo eBay ngaphezu uqikelelo eguqulweyo yabaxwa elula ukuba sicinge ubudlelwane ezinga lidibanise iindidi ezininzi ezahlukeneyo izinto. Ezi uqikelelo inobuqhophololo ngaphezu ukubonisa amandla ahambelana data enkulu; ezi qikelelo ukuba ngendandikwazile ngaphandle inani elikhulu experimenti endle, eya kuba prohibitively eninzi.

Kakade ke, simele sibe nentembelo ngaphantsi kwiziphumo nawuphi sifundo sithile ethelekisa kunathi ubuya iziphumo zovavanyo ezifanayo. Xa kuhlolwa iziphumo kwi nasiphi na isifundo ethelekisa, kukho inkxalabo ezimbini ezibalulekileyo. Okokuqala, kufuneka sikhumbule ukuba sikwazi ukuqinisekisa kuphela uthelekiso fair izinto ezazisetyenziswa wokutshatisa. Kwiziphumo zazo eziphambili, Einav noogxa abazange ngqo elingqinelana neempawu ezine: Inombolo umthengisi ID, udidi item, isihloko item, nezihlokwana. Ukuba izinto zazahlukile ngeendlela engakange kusetyenziswa wokutshatisa, ukuba inokudala uthelekiso olungafanelekanga. Umzekelo, ukuba "budgetgolfer" Bazithule amaxabiso Taylormade sokukhuphela 09 Driver ebusika (xa iiklabhu igalufa mancinane ethandwayo), ngoko oko kubonakala ukuba amaxabiso lokuqalisa asezantsi kukhokelela ukuba zehlise amaxabiso wokugqibela, xa enyanisweni oku kuba bento ngokwamaxesha ukwahlukahlukana nemfuno. Ngokubanzi, indlela engcono le ngxaki ibonakala ukuba uzama iintlobo ezininzi ezahlukeneyo matching. Umzekelo, Einav nabalingane phinda kuhlalutyo lwabo apho iiseti etelekiswe zibandakanya izinto ezinamaxabiso kwisithuba sonyaka omnye, ingaphelanga inyanga enye, kwaye contemporaneously. Ukwenza ixesha window abambeke unciphisa inani iiseti etelekiswe, kodwa kunciphisa iinkxalabo malunga ukwahluka ngokwamaxesha. Ngethamsanqa, baye bafumanise ukuba iziphumo zezi ingaguqukanga zezi utshintsho kumgaqo athelekisekayo. Kuncwadi ethelekisa, olu hlobo inkxalabo ngokuqhelekileyo kuvakalisiweyo ngokuphathelele observables kunye unobservables, kodwa ingcamango isitshixo ngokwenene ukuba abaphandi zidala kuphela uthelekiso fair phezu iimpawu ezisetyenziswa matching.

Eyona nto yesibini enkulu xa ukutolika iziphumo ezithelekisekayo kukuba kusebenza kuphela data etelekiswe; ukuba awasebenzi amatyala ezazingenakulinganiswa ngqa. Ngokomzekelo, ngokunciphisa ngophando lwabo izinto kwafuneka dweliso ezininzi Einav kunye noogxa ezigqale abathengisi zobungcali semi-yobungcali. Ngoko, xa kuchazwa ezi uthelekiso kufuneka sikhumbule ukuba isicelo kuphela kule olusezantsi lwe eBay.

Ukutshatisa yindlela enamandla unokubafumana uthelekiso fair iiseti ezinkulu. Ukuba izazinzulu ezininzi zentlalo, ukutshatisa uziva ngathi yesibini-ibhetele imifuniselo, kodwa kukukholelwa ekufuneka zihlaziywe, kancinane. Ukutshatisa kwi data kakhulu kunokuba bhetele inani elincinane eksperimenti endle xa: 1) ukungafani kwi iziphumo kubalulekile kwaye 2) kukho observables okulungileyo wokutshatisa. Uluhlu 2.4 lunika ezinye imizekelo yendlela kuthelekiseka zingasetyenziswa kunye imithombo yedatha enkulu.

Elokuphetha, iindlela abangazi ukuqikelela iziphumo nakuyo ukusuka data non-zovavanyo ziyingozi. Noko ke, izicwangciso zokwenza uqikelelo nakuyo elele ecaleni continuum ukusuka iingwanyalala ukuya lingenamandla, kunye nabaphandi Lunokufumanisa uthelekiso fair ngaphakathi data non-zovavanyo. Ukukhula usoloko-on, iinkqubo data enkulu kwandisa amandla ethu ukusebenzisa kakuhle iindlela ezikhoyo ezimbini: imifuniselo zendalo ezingqameneyo.