2.4.3 Approximating zatsopano

Titha kuyesa pafupi zomwe sitinathe kapena zomwe sitingathe kuchita. Njira ziwiri zomwe zimapindula kwambiri ndi zikuluzikulu za deta ndizoyesera zachilengedwe ndi zofanana.

Mafunso ena ofunika kwambiri a sayansi ndi ndondomeko ndizovuta. Mwachitsanzo, kodi zotsatira za pulogalamu ya maphunziro pa malipiro ndi zotani? Wochita kafukufuku wakuyesera kuyankha funsoli akhoza kuyerekeza phindu la anthu omwe adasainira maphunziro awo kwa omwe sanatero. Koma kodi malipiro amtundu wanji pakati pa maguluwa ndi chifukwa cha maphunziro ndi kuchuluka kotani chifukwa cha kusiyana kwakukulu pakati pa anthu omwe amalembetsa ndi omwe sachita? Ili ndi funso lovuta, ndipo ndilo limene silitha kuchoka ndi deta zambiri. Mwa kuyankhula kwina, kudera nkhawa za zovuta zotsutsana zingakhalepo ngakhale kuti ndi antchito angati omwe ali mu deta yanu.

Nthawi zambiri, njira yamphamvu kwambiri yowerengera kuti mankhwalawa amatha bwanji, monga ntchito yophunzitsira ntchito, ndi kuyesa kachitidwe kafukufuku komwe katswiri amapereka mankhwala kwa anthu ena osati ena. Ndipatseni chaputala 4 kuti ndiyesere, kotero ndikuwonetsani njira ziwiri zomwe zingagwiritsidwe ntchito ndi deta yosayesera. Njira yoyamba imadalira kuyang'ana chinachake chomwe chikuchitika m'dziko lapansi mwachangu (kapena mwachisawawa) amapereka mankhwala kwa anthu ena osati ena. Njira yachiwiri ikudalira pakuwerengetsera chiwerengero chosasanthula pofuna kuyesa kusiyana pakati pa omwe adachita komanso sanalandire chithandizo.

Wokayikira anganene kuti njira zonse izi ziyenera kupeŵedwa chifukwa zimafuna kuganiza mozama, zomwe zimakhala zovuta kuzifufuza komanso kuti nthawi zambiri zimaphwanyidwa. Ngakhale ndikukumvera chifundo ichi, ndikuganiza kuti chimapita kutali kwambiri. Ndizoona kuti ndi kovuta kupanga moyenera kulingalira za deta yosasanthula, koma sindikuganiza kuti sitiyenera kuyesa. Makamaka, njira zopanda kuyesera zingakhale zothandiza ngati choyimitsa chinsinsi chimakulepheretsani kuchita zoyesayesa kapena ngati zovuta zoyenera zimatanthauza kuti simukufuna kuyesa kuyesa. Kuwonjezera pamenepo, njira zopanda kuyesera zingakhale zothandiza ngati mukufuna kugwiritsa ntchito deta yomwe ilipo kale kuti mupange kuyesera kosayendetsedwa bwino.

Musanapitirize, ndiyeneranso kuzindikira kuti kupanga zowerengera zapadera ndi chimodzi mwa nkhani zovuta kwambiri pakufufuza kafukufuku, komanso zomwe zingayambitse kutsutsana kwambiri. M'tsata lotsatila, ndikupereka ndondomeko yokhudzana ndi njira iliyonse kuti ndikhale ndi chidziwitso cha izo, ndiye ndikufotokozera zina mwa zovuta zomwe zimabwera mukamagwiritsa ntchito njirayi. Zambiri zokhudza njira iliyonse zilipo mu zipangizo kumapeto kwa mutu uno. Ngati mukukonzekera kugwiritsa ntchito njira imodziyi mufukufuku wanu, ndikulimbikitsanso kuwerenga imodzi mwa mabuku abwino kwambiri pazinthu zosiyana siyana (Imbens and Rubin 2015; Pearl 2009; Morgan and Winship 2014) .

Njira imodzi yopangira chiwerengero cha deta yosadziŵika ndi kuyang'ana chochitika chomwe mwadzidzidzi chinapereka mankhwala kwa anthu ena osati kwa ena. Izi zimatchedwa kuyesera zachirengedwe . Chimodzi mwa zitsanzo zowoneka bwino zachilengedwe zimabwera kuchokera ku kafukufuku wa Joshua Angrist (1990) poyerekeza ndi zotsatira za ntchito za usilikali pamalipiro. Panthawi ya nkhondo ku Vietnam, United States inakula kukula kwa zida zake kupyolera mu ndondomeko. Pofuna kusankha kuti nzika ziti zidzaitanidwe, boma la United States linagwira loti. Tsiku lililonse la kubadwa linalembedwa papepala, ndipo, monga momwe tawonetsera pachithunzi 2.7, mapepalawa anasankhidwa imodzi panthawi kuti adziwe dongosolo lomwe anyamata adzaitanidwe kuti azitumikira (atsikana sanagonjere mpaka pamsonkhanowu). Malingana ndi zotsatira, amuna omwe anabadwa pa September 14 adatchedwa oyambirira, amuna obadwa pa April 24 amatchedwa wachiwiri, ndi zina zotero. Potsirizira pake, mu lottery iyi, amuna obadwa masiku 195 osiyanasiyana analembedwa, pamene amuna obadwa masiku 171 sanali.

Chithunzi cha 2.7: Congressman Alexander Pirnie (R-NY) akujambula kapule yoyamba yopanga chisankho cha Selective pa December 1, 1969. Joshua Angrist (1990) adagwirizanitsa kukonza loti ndi ndalama zochokera ku Social Security Administration kuti azindikire zotsatira za ntchito ya usilikali pa malipiro. Ichi ndi chitsanzo cha kafukufuku pogwiritsa ntchito kuyesera kwachirengedwe. Gwero: US Selective Service System (1969) / Wikimedia Commons .

Ngakhale kuti sizingakhale zoonekeratu, kukonzekera loti kumakhala kofanana kwambiri ndi kuyesedwa kosasinthika: muzochitika zonsezi, ophunzira amapatsidwa mwayi wopeza chithandizo. Pofuna kudziwa zotsatira za chithandizochi, Angrist adagwiritsa ntchito njira yodalirika yodalirika: US Social Security Administration, yomwe imasonkhanitsa uthenga pafupifupi pafupifupi malipiro onse a ku America kuchokera kuntchito. Mwa kuphatikizapo chidziwitso chokhudza omwe anasankhidwa mwachindunji mu loti ya loti yomwe ili ndi deta yomwe inasonkhanitsidwa m'mabuku a boma, Angrist anamaliza kuti mapeto a anthu oyamenya nkhondo anali pafupifupi 15 peresenti yochepa kusiyana ndi malipiro a anthu omwe sali amkhondo.

Monga momwe chitsanzo ichi chikusonyezera, nthawi zina zokhudzana ndi chikhalidwe, ndale, kapena zachirengedwe zimapereka chithandizo m'njira yomwe ingayambidwe ndi ochita kafukufuku, ndipo nthawi zina zotsatira za mankhwalawa zimagwiritsidwa ntchito nthawi zonse. Njira iyi yofufuzira ikhoza kufotokozedwa motere: \[\text{random (or as if random) variation} + \text{always-on data} = \text{natural experiment}\]

Kuti tifotokoze njirayi mu nthawi ya digito, tiyeni tione kafukufuku wina wa Alexandre Mas ndi Enrico Moretti (2009) omwe adayesera kulingalira zotsatira za kugwira ntchito ndi ogwira ntchito ogwira ntchito popanga ntchito. Musanawone zotsatira, ndi bwino kutsimikizira kuti pali ziyembekezo zosiyana zomwe mungakhale nazo. Kumbali imodzi, mukhoza kuyembekezera kuti kugwira ntchito ndi ogwira nawo ntchito kumathandiza wogwira ntchito kuonjezera zokolola zake chifukwa cha kukakamizidwa ndi anzanu. Kapena, mungathe kuyembekezera kuti kukhala ndi anzanu ogwira ntchito mwakhama kungapangitse antchito kusiya ntchito chifukwa ntchitoyo idzachitidwa ndi anzawo. Njira yowonjezera yophunzira zotsatira za anzawo pa zokolola ndizomwe mungayesetsedwe mwadzidzidzi kumene antchito amapatsidwa ntchito mosasintha ndi ogwira ntchito zosiyanasiyana zokolola ndipo zotsatira zake zimayesedwa kwa aliyense. Ochita kafukufuku samatsata ndondomeko ya antchito mu bizinesi yeniyeni, kotero Mas ndi Moretti adayenera kudalira zochitika zachilengedwe zokhudzana ndi ndalama m'masitolo.

Msika waukuluwu, chifukwa cha njira yomwe ndondomeko idakwaniritsidwira komanso momwe njirayi inagwirira ntchito, munthu aliyense wogulitsa ntchitoyo anali ndi ogwira nawo ntchito panthawi zosiyanasiyana. Kuwonjezera apo, mu supamakeyi yapaderayi, ntchito ya osunga ndalama sizinagwirizane ndi zokolola za anzawo kapena momwe sitoloyo inali yotanganidwa. Mwa kuyankhula kwina, ngakhale kuti ndondomeko ya osungira ndalama siinadziwitsidwe ndi lottery, zinali ngati antchito nthawizina ankapatsidwa mwayi wochita ntchito ndi anzawo apamwamba (kapena otsika). Mwamwayi, chipindachichi chinakhalanso ndi mawotchi a zaka zapamwamba omwe ankawona zinthu zomwe aliyense wosungira ndalama ankazifufuza nthawi zonse. Kuchokera ku deta yowunikirayi, Mas ndi Moretti adatha kupanga zofunikira, zofunikira, komanso nthawi zonse zokolola: chiwerengero cha zinthu zomwe zasankhidwa pamphindi. Kuphatikiza zinthu ziwirizi-zochitika mwachibadwa pa zochitika za anzako komanso nthawi zonse zokolola-Mas ndi Moretti amaganiza kuti ngati munthu wothandizira ndalama atapatsidwa antchito omwe anali oposa 10% opindulitsa kuposa owerengeka, zokolola zake zidzawonjezeka ndi 1.5% . Kuwonjezera apo, iwo ankagwiritsa ntchito kukula ndi kulemera kwa deta yawo kuti afufuze zinthu ziwiri zofunika: kusagwirizana kwa zotsatirazi (Pakuti mitundu yanji ya antchito ndi zotsatira zake zazikuru?) Ndi njira zomwe zimachokera kumapeto (Chifukwa chiyani kukhala ndi zotsatira zabwino za anzanu kumatsogolera ku zokolola zapamwamba?). Tibwereranso kuzinthu ziwiri zofunika-kusokoneza kwa zotsatira za mankhwala ndi njira-mu chaputala 4 pamene tikambirana zofufuza mwatsatanetsatane.

Pogwiritsa ntchito maphunziro awiriwa, mndandanda wa 2.3 umaphatikizapo maphunziro ena omwe ali ndi ndondomeko yomweyo: kugwiritsa ntchito nthawi zonse zopezera deta kuti azindikire zotsatira za kusintha kwasintha. Mwachizoloŵezi, ochita kafukufuku amagwiritsa ntchito njira ziwiri zopezera kuyesayesa kwachilengedwe, zonse zomwe zingathe kubala zipatso. Ofufuza ena amayamba ndi zopezeka pa deta nthawi zonse ndikuyang'ana zochitika zosadziwika pa dziko; ena amayamba zochitika zosayembekezereka padziko lapansi ndikuyang'ana malo omwe atulukirapo deta omwe amawombera.

Pa zokambirana zokhudzana ndi masoka achilengedwe, ndasiya mfundo yofunikira: kuchoka ku chikhalidwe chomwe chaperekedwa ku zomwe mukufuna nthawi zina zimakhala zovuta. Tiyeni tibwerere ku chitsanzo cha Vietnam. Pachifukwa ichi, Angrist anali ndi chidwi cholingalira zotsatira za ntchito ya usilikali pamalipiro. Mwatsoka, ntchito ya usilikali sinali yopatsidwa mwachangu; m'malo mwake anali kulembedwa kuti wapatsidwa mwachangu. Komabe, sikuti aliyense amene adalembedwera akutumizidwa (panali zosiyana siyana), ndipo si onse omwe adatumikira adali kulembedwa (anthu angadzipereke kutumikira). Chifukwa chakuti kukonzedwa kwalembedwa kunaperekedwa mwachisawawa, wofufuza akhoza kulingalira zotsatira za kukonzekera kwa amuna onse muzolemba. Koma Angrist sanafune kudziwa zotsatira za kukonzedwa; iye ankafuna kudziwa zotsatira za kutumikira mu usilikali. Komabe, kuti muyese kulingalira uku, zowonjezerapo zowonjezera ndi zovuta zimayenera. Choyamba, ochita kafukufuku ayenera kuganiza kuti njira yokha yomwe kukonzedweratu kunakhudzidwa ndi malipiro ndi kupyolera muutumiki wamasewera, lingaliro lotchedwa lamulo loletsedwa . Lingaliro limeneli lingakhale lolakwika ngati, mwachitsanzo, amuna omwe analembedwera adakhala kusukulu nthawi yaitali kuti asatumikire kapena ngati olemba ntchito sankatha kukonzekera amuna omwe adalembedwa. Mwachidziwitso, lamulo loletsedwa ndilo lingaliro lalikulu, ndipo nthawi zambiri zimakhala zovuta kutsimikizira. Ngakhale ngati lamulo loletsedwa likulondola, ndizosatheka kulingalira zotsatira za utumiki kwa anthu onse. M'malo mwake, ochita kafukufuku amatha kuwonetsa zotsatira za amuna omwe amatchedwa compliers (amuna omwe angatumikire pamene adalembedwa, koma sangatumikire pamene sanalembedwe) (Angrist, Imbens, and Rubin 1996) . Komabe, ndalama zopanga ndalama sizinali zoyambirira. Tawonani kuti mavutowa amadza ngakhale muzoyera zoyenera za polojekiti ya loti. Mavuto ena amayamba pamene mankhwala samaperekedwa ndi lotiyo. Mwachitsanzo, mu maphunziro a Mas ndi a Moretti ochotsa ndalama, mafunso ena amadzapo ponena za lingaliro lakuti ntchito ya anzako imakhala yopanda phindu. Ngati kuganiza uku kunaphwanyidwa molakwa, kukhoza kuyesa chiwerengero chawo. Pomaliza, mayesero achilengedwe angakhale njira yamphamvu yopangira chiwerengero chokhazikika kuchokera ku deta yosadziŵika, ndipo zida zazikulu za deta zimachulukitsa luso lathu loyesa kuzigwiritsa ntchito poyesera zakuthupi pamene zichitika. Komabe, izo ziyenera kumafuna kusamala kwambiri-ndipo nthawizina malingaliro amphamvu-kuti achoke ku chikhalidwe chomwe wapereka kwa kulingalira komwe iwe ukukufuna.

Njira yachiwiri yomwe ndikufuna kukuuzani zapangidwe yodalirika kuchokera ku deta yosasanthula imadalira kusintha kwa chiwerengero cha deta yosayesayesa pofuna kuyesa kusiyana pakati pa omwe adachita komanso sanalandire chithandizo. Pali kusintha kotereku, koma ndikuyang'ana pa imodzi yotchedwa yofanana . Pofananitsa, wofufuzira amayang'ana kudutsa deta yosayesera kuti apange awiri awiri omwe ali ofanana koma kupatula kuti wina walandira chithandizo ndipo wina alibe. Pofuna kufanana, ofufuza akukonzanso ; kutanthauza kuti, kutaya milandu yomwe palibe mzere wowonekera. Choncho, njira iyi idzakhala yotchulidwa molondola komanso yowonongeka, koma ndikugwirizana ndi mwambo wotsatira: kufanana.

Chitsanzo chimodzi cha mphamvu zowonongeka ndi zowonjezereka zochokera ku deta zimachokera ku kafukufuku wochita malonda ndi Liran Einav ndi anzake (2015) . Iwo ankakonda chidwi cha malonda omwe akuchitika pa eBay, ndipo pofotokoza ntchito yawo, ine ndikuganizira za zotsatira za malonda kuyambira mtengo pa zotsatira za malonda, monga mtengo wogulitsa kapena mwayi wogulitsa.

Njira yosadziwika ya kulingalira zotsatira za mtengo woyambira pa mtengo wogulitsa kungokhala kuwerengera mtengo wotsiriza wa zotsatsa malonda ndi mitengo yoyamba yosiyana. Njirayi ikanakhala yabwino ngati mukufuna kufotokoza mtengo wogulitsa womwe wapatsidwa mtengo woyambira. Koma ngati funso lanu likukhudzana ndi zotsatira za mtengo woyambira, njirayi sichitha kugwira ntchito chifukwa sichikufanizidwa ndi kuyerekezera mwachilungamo; malonda omwe ali ndi mitengo yoyamba yochepa akhoza kukhala osiyana kwambiri ndi omwe ali ndi mitengo yowonjezereka (mwachitsanzo, akhoza kukhala a mitundu yosiyanasiyana ya katundu kapena akuphatikizapo mitundu yosiyanasiyana ya ogulitsa).

Ngati mwadziwa kale mavuto omwe angabwere pokonzekera kuchuluka kwa deta yomwe simukuyesera, mukhoza kudutsa njira yopanda nzeru ndikuganiza kuti mukuyesa kuyesa malo omwe mungagulitse chinthu china, galasi-yokhazikika Mitengo yotsatsa-imati, kutumiza kwaulere ndi malonda kwamasabata awiri-koma ndi mitengo yoyamba yoperekedwa. Poyerekeza zotsatira za msika, zotsatirazi zapaderazi zingapereke chiyero choonekera cha zotsatira za mtengo woyambira pa mtengo wogulitsa. Koma muyeso uwu ukhoza kugwiritsidwa ntchito ku chinthu chimodzi chokha ndi kukhazikitsa magawo a malonda. Zotsatira zingakhale zosiyana, mwachitsanzo, kwa mitundu yosiyanasiyana ya zinthu. Popanda chiphunzitso cholimba, n'zovuta kufotokozera kuchokera kuyesayesa kamodzi kuti zitha kuyendetsedwa bwino. Kuwonjezera pamenepo, kuyesa kwapadera kuli okwera mtengo moti sikungatheke kuyendetsa zosiyanasiyana zomwe mungafune kuyesa.

Mosiyana ndi njira zopanda nzeru komanso zoyesera, Einav ndi anzake anatsatira njira yachitatu: kuyanjana. Chinyengo chachikulu mu njira yawo ndi kupeza zinthu zofanana ndi zoyesera zomwe zachitika kale pa eBay. Mwachitsanzo, chiwerengero cha 2.8 chikuwonetsera zina mwa mapepala okwana 31 omwe ali ndi galimoto ya Taylormade Burner 09 yomwe ikugulitsidwa ndi wogulitsa chimodzimodzi- "budgetgolfer." Komabe, mndandanda wa 31wu uli ndi makhalidwe osiyana, monga osiyana kuyambira mitengo, mapeto, ndi malipiro. M'mawu ena, zimakhala ngati "budgetgolfer" ikuyesa mayesero kwa ofufuza.

Mndandanda wa Taylormade Burner 09 Dalaivala yogulitsidwa ndi "budgetgolfer" ndi chitsanzo chimodzi cha mndandanda wa mndandanda, pomwe chinthu chomwecho chikugulitsidwa ndi wogulitsa chimodzimodzi, koma nthawi iliyonse ndi zizindikiro zosiyana. M'magulu akuluakulu a eBay alipo kwenikweni zikwi mazana zikwi zofanana zomwe zikuphatikizapo mamiliyoni a mndandanda. Choncho, m'malo moyerekezera mtengo wotsiriza wa malonda onse ndi mtengo woyambirira woperekedwa, Einav ndi anzake amagwirizanitsa ndi maselo ofanana. Pofuna kuyanjanitsa zotsatira za kufananitsidwa pakati pa magulu zikwi mazana zikwi zofanana, Einav ndi anzake adalongosola mtengo woyambira ndi mtengo wotsiriza pokhudzana ndi chiwerengero cha chinthu chilichonse (mwachitsanzo, mtengo wake wogulitsa). Mwachitsanzo, ngati Taylormade Burner 09 Driver anali ndi ndalama zokwana madola 100 (malingana ndi malonda ake), ndiye kuti mtengo woyamba wa $ 10 udzakhala ngati 0.1 ndipo mtengo wotsiriza wa $ 120 ngati 1.2.

Chithunzi 2.8: Chitsanzo chayiyi yofanana. Izi ndizofanana ndi galimoto ya golf ya Taylormade Burner 09 yomwe ikugulitsidwa ndi munthu yemweyo (budgetgolfer), koma zina mwa malondawa anachitidwa mosiyana siyana (mwachitsanzo, mitengo yoyamba yosiyana). Kubwerezedwa ndi chilolezo kuchokera kwa Einav et al. (2015) , chifaniziro 1b.

Kumbukirani kuti Einav ndi anzako ankachita chidwi ndi zotsatira za mtengo woyambirira pa zotsatira za malonda. Choyamba, iwo ankagwiritsa ntchito njira yowonongeka yowonongeka kuti awonetse kuti mitengo yowonjezera yoyamba imachepetsa mwayi wogulitsa, ndipo kuti mitengo yowonjezera yoyamba imapereka mtengo wotsiriza wogulitsa (malingaliro pa kugulitsa kumachitika). Mwa iwo okha, kulingalira uku-kumene kumalongosola ubale wofanana ndi kuwerengedwa pazinthu zonse-sizo zonse zokondweretsa. Kenaka, Einav ndi anzake amagwiritsira ntchito kukula kwake kwa deta kuti apange ziwerengero zosaoneka zambiri. Mwachitsanzo, poyesa zotsatira zake zosiyana pa mitengo yoyamba yosiyana siyana, adapeza kuti mgwirizano pakati pa mtengo woyambirira ndi mtengo wogulitsa uli woslinear (chithunzi 2.9). Makamaka, poyambira mitengo pakati pa 0.05 ndi 0.85, mtengo woyambirira uli ndi zotsatira zochepa pa mtengo wogulitsa, kupeza kuti kunali kosawonongeka kwambiri ndi kafukufuku wawo woyamba. Kuwonjezera apo, m'malo mofotokozera zinthu zonse, Einav ndi anzake amaganiza kuti chiyambi cha mtengo wa mitundu 23 ya zinthu (mwachitsanzo, zopereka za pet, zamagetsi, ndi masewero a masewera) (Chithunzi 2.10). Ziwerengero izi zikuwonetsa kuti zinthu zina zosiyana-monga kukumbukira-mtengo woyambira uli ndi zotsatira zochepa pa mwayi wa kugulitsa ndi zotsatira zazikulu pa mtengo wotsiriza wogulitsa. Komanso, pazinthu zowonjezereka monga DVDs-mtengo woyambira ulibe mphamvu iliyonse pamtengo wotsiriza. Mwa kuyankhula kwina, chiŵerengero chophatikiza zotsatira kuchokera pa mitundu 23 ya zinthu zimaphimba kusiyana kwakukulu pakati pa zinthu izi.

Chithunzi 2.9: Chiyanjano pakati pa mtengo wogulitsira kuyambira mtengo ndi mwayi wa kugulitsa (a) ndi mtengo wogulitsa (b). Pali kusiyana kwakukulu pakati pa kuyamba mtengo ndi mwayi wogulitsa, koma ubale wosagwirizana pakati pa kuyamba mtengo ndi mtengo wogulitsa; poyambira mitengo pakati pa 0.05 ndi 0.85, mtengo woyambirira uli ndi zotsatira zochepa pa mtengo wogulitsa. Pazochitika zonsezi, maubwenzi ali osiyana ndi mtengo wa mtengo. Kuchokera kwa Einav et al. (2015) , masamba 4a ndi 4b.

Chithunzi 2.10: Kuwerengera kuchokera ku gawo lililonse la zinthu; Dothi lolimba ndikulingalira kwa magulu onse ogwirizana (Einav et al. 2015) . Zotsatira izi zikuwonetsa kuti zinthu zina zosiyana-monga kukumbukira-mtengo woyamba uli ndi zotsatira zochepa zogulitsa ( \(x\) -axis) ndi zotsatira zazikulu pa mtengo wogulitsa womaliza ( \(y\) -axis). Kuchokera kwa Einav et al. (2015) , chithunzi 8.

Ngakhale simukukonda kwambiri malonda a eBay, muyenera kuyamikira momwe chiwerengero cha 2.9 ndi chifaniziro cha 2.10 chimaperekera kumvetsetsa kwa eBay kusiyana ndi kulingalira kosavuta komwe kumalongosola mgwirizano wapadera ndikuphatikiza mitundu yambiri ya zinthu. Komanso, ngakhale kuti zingatheke kuti sayansi ikhale yopanga zowonongeka zowonjezereka ndi zofufuza zapadera, mtengowo ukhoza kuyesa zowonongeka koteroko.

Monga momwe zowonetsera zachilengedwe, pali njira zingapo zomwe zimagwirizanitsa zingabweretse ku ziwerengero zoipa. Ndikuganiza kuti chodetsa nkhaŵa kwambiri ndi kuyerekezera chiwerengero ndi chakuti akhoza kukonda zinthu zomwe sizinagwiritsidwe ntchito mofanana. Mwachitsanzo, mu zotsatira zawo zazikulu, Einav ndi anzake amagwira ntchito molingana ndi makhalidwe anai: chiwerengero cha chigulitsi cha wogulitsa, chigawo cha katundu, mutu wa mutu, ndi mutu wankhani. Ngati zinthuzo zinali zosiyana m'njira zomwe sizinagwiritsidwe ntchito kuti zifanane, ndiye izi zingapangitse kulinganitsa kosayenera. Mwachitsanzo, ngati "budgetgolfer" inachepetsa mitengo ya Taylormade Burner 09 yozizira m'nyengo yozizira (pamene magulu a golf ali otchuka kwambiri), ndiye kuti zikhoza kuwoneka kuti mitengo yochepa yoyambira imachepetsera mtengo wotsiriza, kusintha kwa nyengo pakufunidwa. Njira imodzi yothetsera vutoli ndikuyesa mitundu yambiri yofanana. Mwachitsanzo, Einav ndi anzake amagwiranso ntchito mobwerezabwereza poyesa kusinthanitsa pamene nthawi yofanana yomwe ikugwiritsidwa ntchito yofananako (yofanana yomwe ikuphatikizidwa inali ndi zinthu zogulitsa chaka chimodzi, mkati mwa mwezi umodzi, komanso mwachindunji). Mwamwayi, adapeza zotsatira zofanana ndi mawindo onse a nthawi zonse. Chodetsa nkhaŵa kwambiri ndi kufanana kumachokera kukutanthauzira. Chiwerengero chofanana chikugwiritsidwa ntchito pa data; iwo samagwira ntchito ku milandu yomwe sitingagwirizane. Mwachitsanzo, mwa kuchepetsa kafukufuku wawo ku zinthu zomwe zili ndi mndandanda wazinthu zambiri, Einav ndi anzake akuyang'ana ogulitsa ogwira ntchito komanso odziwa ntchito. Choncho, potanthauzira mafanizo awa tiyenera kukumbukira kuti amangogwiritsa ntchito ku eBay iyi.

Kufananitsa ndi njira yamphamvu yopezera kufanizirana kosalungama mu deta yosayesa. Kwa akatswiri ambiri asayansi, kufanana kumakhala kachiwiri-kuyesera kuyesa, koma ndizo chikhulupiriro chomwe chingathe kubwerezedwa, pang'ono. Kufananirana ndi deta yaikulu kungakhale bwino kusiyana ndi chiwerengero chochepa cha masewera pamene (1) zotsatira zogwirizana ndi zofunikira ndi (2) zofunikira zofunika zofananako zawerengedwa. Phunziro 2.4 limapereka zitsanzo zina zogwirizana momwe zingagwiritsidwe ntchito ndi magulu akuluakulu.

Pomalizira, kuyerekezera zotsatira zowonongeka kuchokera ku deta yosadziwika ndi kovuta, koma njira monga zowonetsera masoka ndi kusintha kwa chiwerengero (mwachitsanzo, kufanana) zingagwiritsidwe ntchito. Nthawi zina, njirazi zikhoza kuyenda molakwika, koma zikagwiritsidwa mosamala, njirazi zingakhale zothandiza kumayesetsero omwe ndikuwunika mu chaputala 4. Kuwonjezera apo, njira ziwirizi zikuwoneka kuti zingapindule ndi kukula kwa nthawi zonse- pa, ndondomeko zazikulu za deta.