Nkhani yochokera ku gulu la Stitch Fix ikuwonetsa kugwiritsa ntchito njira yoyesera yocheperako pakutsatsa ndi mayeso a A/B. Njirayi imagwira ntchito pamene tikuyesa njira yatsopano yomwe ili ndi phindu lomwe silinayesedwe ndi mayesero.
Chitsanzo chosavuta ndicho kuchepetsa mtengo. Mwachitsanzo, timasintha njira yoperekera phunziro loyamba, koma sitikufuna kuchepetsa kutembenuka komaliza mpaka kumapeto. Kapena timayesa zosintha zomwe zimayang'ana gawo limodzi la ogwiritsa ntchito, ndikuwonetsetsa kuti kutembenuka kwa magawo ena sikutsika kwambiri (poyesa malingaliro angapo, musaiwale za zosinthazo).
Kusankha malire olondola osakhala otsika kumawonjezera zovuta zina panthawi yoyeserera. Funso la momwe mungasankhire Δ silinatchulidwe bwino m'nkhaniyi. Zikuwoneka kuti chisankhochi sichikuwonekeranso m'mayesero achipatala. zofalitsa zachipatala pa osakhala otsika lipoti kuti theka lokha la zofalitsa limavomereza kusankha malire, ndipo nthawi zambiri zodzilungamitsa izi zimakhala zosamvetsetseka kapena zosalongosoka.
Mulimonsemo, njira iyi ikuwoneka yosangalatsa chifukwa ... pochepetsa kukula kwachitsanzo chofunikira, kumatha kukulitsa liwiro la kuyesa, motero, liwiro la kupanga zisankho. - Daria Mukhina, wowunika zazinthu zam'manja za Skyeng.
Gulu la Stitch Fix limakonda kuyesa zinthu zosiyanasiyana. Gulu lonse laukadaulo limakonda kuyesa mayeso mwatsatanetsatane. Ndi tsamba liti lomwe limakopa ogwiritsa ntchito ambiri - A kapena B? Kodi mtundu A wa mtundu wovomerezeka umapanga ndalama zambiri kuposa mtundu B? Kuti tiyese zongoyerekeza, pafupifupi nthawi zonse timagwiritsa ntchito njira yosavuta kuchokera ku maphunziro oyambira owerengera:
Ngakhale kuti sitigwiritsa ntchito mawuwa kawirikawiri, kuyesa kumeneku kumatchedwa "kuyesa kwapamwamba kwambiri." Ndi njira iyi, timaganiza kuti palibe kusiyana pakati pa zosankha ziwirizi. Timamamatira ndi lingaliro ili ndikungosiya ngati deta ikukakamiza mokwanira kutero - ndiko kuti, ikuwonetsa kuti imodzi mwazosankha (A kapena B) ndi yabwino kuposa ina.
Kuyesa lingaliro lapamwamba ndiloyenera pamavuto osiyanasiyana. Timangotulutsa mtundu wa B wachitsanzo ngati uli bwino kuposa mtundu A womwe ukugwiritsidwa ntchito kale. Koma nthawi zina, njirayi sigwira ntchito bwino. Tiyeni tione zitsanzo zingapo.
1) Timagwiritsa ntchito gulu lachitatu, zomwe zimathandiza kuzindikira makhadi akubanki achinyengo. Tapeza ntchito ina yotsika mtengo kwambiri. Ngati ntchito yotsika mtengo ikugwira ntchito mofanana ndi yomwe tikugwiritsa ntchito panopa, tidzasankha. Siziyenera kukhala zabwino kuposa ntchito yomwe mukugwiritsa ntchito.
2) Tikufuna kusiya gwero la data A ndikusintha ndi gwero la data B. Titha kuchedwetsa kusiya A ngati B atulutsa zotsatira zoyipa kwambiri, koma sizingatheke kupitiliza kugwiritsa ntchito A.
3) Tikufuna kuchoka ku njira yachitsanzoNjira ya A kupita ku B osati chifukwa timayembekezera zotsatira zabwino kuchokera ku B, koma chifukwa imatipatsa kusinthasintha kwa magwiridwe antchito. Tilibe chifukwa chokhulupirira kuti B idzakhala yoipitsitsa, koma sitidzasintha ngati ndi choncho.
4) Tapanga zosintha zingapo zamakhalidwe m'mapangidwe a webusayiti (mtundu B) ndikukhulupirira kuti bukuli ndilapamwamba kuposa mtundu A. Sitikuyembekezera kusintha kwakusintha kapena zizindikiro zilizonse zazikuluzikulu zomwe timayesa webusayiti. Koma timakhulupirira kuti pali zopindulitsa mu magawo omwe sangayesedwe kapena ukadaulo wathu siwokwanira kuyeza.
Pazochitika zonsezi, kufufuza kwapamwamba sikuli yankho loyenera kwambiri. Koma akatswiri ambiri muzochitika zotere amazigwiritsa ntchito mwachisawawa. Timayesa mosamala kuti tidziwe bwino kukula kwa zotsatira zake. Zikanakhala zoona kuti matembenuzidwe A ndi B amagwira ntchito mofanana, pali mwayi woti tikanalephere kukana lingaliro lopanda pake. Kodi timaganiza kuti A ndi B amachita chimodzimodzi? Ayi! Kulephera kukana lingaliro lopanda pake ndi kuvomereza malingaliro opanda pake si chinthu chomwecho.
Zitsanzo za kukula kwachitsanzo (zomwe, ndithudi, mwachita) nthawi zambiri zimachitidwa ndi malire amtundu wa mtundu wa I (mwayi wolephera kukana null hypothesis, yomwe nthawi zambiri imatchedwa alpha) kusiyana ndi zolakwika za Type II (mwayi wolephera. kukana lingaliro lopanda pake, potengera kuti lingaliro lopanda pake ndi labodza, lomwe nthawi zambiri limatchedwa beta). Mtengo wake wa alpha ndi 0,05, pomwe mtengo wa beta ndi 0,20, wolingana ndi mphamvu yowerengera ya 0,80. Izi zikutanthauza kuti pali mwayi wa 20% woti tidzaphonya zotsatira zenizeni za kuchuluka komwe tafotokoza m'mawerengedwe athu amphamvu, ndipo ndiye kusiyana kwakukulu muzambiri. Mwachitsanzo, tiyeni tilingalire ma hypotheses awa:
H0: chikwama changa sichili m'chipinda changa (3)
H1: chikwama changa chili mchipinda changa (4)
Ndikayang'ana mchipinda changa ndikupeza chikwama changa, chabwino, nditha kukana lingaliro lopanda pake. Koma nditayang'ana m'chipindamo osapeza chikwama changa (chithunzi 1), ndinene chiyani? Kodi ndikutsimikiza kuti palibe? Kodi ndinawoneka molimba mokwanira? Nanga bwanji ndikangofufuza 80% ya chipindacho? Kutsimikiza kuti chikwamacho sichili m'chipindamo chingakhale chisankho chachangu. Nzosadabwitsa kuti sitingathe "kuvomereza mfundo zopanda pake."
Dera lomwe tidafufuza
Sitinachipeze chikwamacho - kodi tiyenera kuvomereza lingaliro lopanda pake?
Chithunzi 1: Kusaka 80% ya chipinda kuli pafupifupi mofanana ndi kufufuza pa 80% mphamvu. Ngati simukupeza chikwama mutayang'ana 80% ya chipindacho, munganene kuti palibe?
Ndiye kodi wasayansi wa data ayenera kuchita chiyani pamenepa? Mukhoza kuonjezera mphamvu ya phunziroli, koma mudzafunika kukula kwachitsanzo chokulirapo ndipo zotsatira zake zidzakhalabe zosasangalatsa.
Mwamwayi, mavuto otere akhala akuphunziridwa kwa nthawi yayitali m'dziko la kafukufuku wamankhwala. Mankhwala B ndi otsika mtengo kuposa mankhwala A; Mankhwala B akuyembekezeka kuyambitsa zotsatira zochepa kuposa Mankhwala A; Mankhwala B ndi osavuta kunyamula chifukwa safunikira kukhala mufiriji, koma mankhwala A amafunikira. Tiyeni tiyese malingaliro a osakhala otsika. Izi ndikuwonetsa kuti mtundu wa B ndi wabwino kwambiri ngati mtundu A-osachepera m'malire otchulidwatu omwe si otsika, Δ. Tikambirana zambiri za momwe tingakhazikitsire malirewo pakapita nthawi. Koma pakadali pano tiyeni tiyerekeze kuti uku ndiko kusiyana kwakung'ono kwambiri komwe kuli kofunikira (m'mayesero achipatala, izi zimatchedwa kufunikira kwachipatala).
Ma hypotheses osakhala otsika amatembenuza chilichonse pamutu pake:
Tsopano, m'malo mongoganiza kuti palibe kusiyana, tidzaganiza kuti mtundu B ndi woipa kuposa mtundu A, ndipo tidzakakamira ndi lingaliro ili mpaka titawonetsa kuti sizili choncho. Iyi ndi nthawi yomwe zili zomveka kugwiritsa ntchito kuyesa kwamalingaliro a mbali imodzi! Pochita izi, izi zikhoza kuchitika mwa kupanga nthawi yodalirika ndikuzindikira ngati nthawiyo ilidi yaikulu kuposa Δ (Chithunzi 2).
Sankhani Δ
Kodi kusankha bwino Δ? Kusankha kwa Δ kumaphatikizapo kulungamitsidwa kwa ziwerengero ndi kuwunika kwakukulu. M'dziko la kafukufuku wazachipatala, pali malangizo omwe amawongolera kuti delta iyenera kuyimira kusiyana kochepa kwambiri kwachipatala - komwe kungapangitse kusiyana. Nawa mawu ochokera ku malangizo aku Europe kuti mudziyese nokha nawo: "Ngati kusiyana kwasankhidwa molondola, nthawi yodalirika yomwe ili pakati pa -∆ ndi 0… ndiyokwanira kusonyeza kuti ndinu otsika. Ngati chotsatirachi sichikuwoneka chovomerezeka, ndiye kuti ∆ sanasankhidwe moyenera.”
Mtsinje suyenera kupitilira kukula kwa mtundu A wokhudzana ndi kuwongolera kowona (placebo/palibe chithandizo), popeza izi zimatipangitsa kunena kuti mtundu B ndi woyipa kuposa kuwongolera kowona, pomwe ikuwonetsa "kusakhala pansi. .” Tiyerekeze kuti mtundu A utayambitsidwa, udasinthidwa ndi mtundu 0 kapena mawonekedwewo kulibe konse (onani Chithunzi 3).
Malingana ndi zotsatira za kuyesa kuyerekezera kwapamwamba, kukula kwa zotsatira E kunawululidwa (ndiko kuti, mwinamwake μ^A-μ^0=E). Tsopano A ndiye muyezo wathu watsopano, ndipo tikufuna kuwonetsetsa kuti B ndi wabwino ngati A. Njira ina yolembera μB−μA≤−Δ (null hypothesis) ndi μB≤μA−Δ. Ngati tikuganiza kuti kuchita ndi chofanana kapena chachikulu kuposa E, ndiye μB ≤ μA−E ≤ placebo. Tsopano tikuwona kuti kuyerekezera kwathu kwa μB kumaposa kwathunthu μA-E, komwe kukana kotheratu lingaliro lopanda pake ndipo likutilola kunena kuti B ndi wabwino ngati A, koma nthawi yomweyo μB ikhoza kukhala ≤ μ placebo, yomwe simalo. tikusowa chiyani. (Chithunzi 3).
Chithunzi 3. Chiwonetsero cha kuopsa kosankha malire osakhala otsika. Ngati kudulako kuli kwakukulu kwambiri, tinganene kuti B ndi wocheperapo kwa A, koma nthawi yomweyo sichidziwika ndi placebo. Sitidzasinthanitsa mankhwala omwe ali othandiza kwambiri kuposa placebo (A) ndi mankhwala omwe ali othandiza ngati placebo.
Kusankha kwa α
Tiyeni tipitirize kusankha α. Mutha kugwiritsa ntchito mtengo wokhazikika α = 0,05, koma izi sizachilungamo. Monga, mwachitsanzo, mukamagula china chake pa intaneti ndikugwiritsa ntchito ma code angapo nthawi imodzi, ngakhale siziyenera kuphatikizidwa - wopangayo adangolakwitsa, ndipo mwachoka. Malinga ndi malamulowo, mtengo wa α uyenera kukhala wofanana ndi theka la mtengo wa α womwe umagwiritsidwa ntchito poyesa malingaliro apamwamba, ndiko kuti, 0,05 / 2 = 0,025.
Kukula kwachitsanzo
Kuyerekeza kukula kwachitsanzo? Ngati mumakhulupirira kuti kusiyana kwenikweni pakati pa A ndi B ndi 0, ndiye kuti kuwerengera kukula kwachitsanzo kumakhala kofanana ndi poyesa lingaliro lapamwamba, kupatula kuti mumasintha kukula kwake ndi malire osakhala apansi, malinga ngati mutagwiritsa ntchito. αnon-otsika bwino = 1/2αpamwamba (αnon-otsika=1/2αpamwamba). Ngati muli ndi chifukwa chokhulupirira kuti njira B ikhoza kukhala yoyipa pang'ono kuposa A, koma mukufuna kutsimikizira kuti ndiyoyipa kwambiri kuposa Δ, ndiye kuti muli ndi mwayi! Izi zimachepetsa kukula kwa zitsanzo zanu chifukwa ndizosavuta kuwonetsa kuti B ndiyoyipa kuposa A ngati mukuganiza kuti ndiyoyipa pang'ono kuposa yofanana.
Chitsanzo ndi yankho
Tiyerekeze kuti mukufuna kukulitsa mtundu wa B, pokhapokha ngati siposa 0,1 mfundo yoyipa kuposa mtundu A pamlingo wokhutiritsa wamakasitomala a 5... Tiyeni tiyang'ane vutoli pogwiritsa ntchito lingaliro lapamwamba.
Kuti tiyese hypothesis yapamwamba, tidzawerengera kukula kwake motere:
Ndiye kuti, ngati muli ndi zowonera 2103 mu gulu lanu, mutha kukhala ndi chidaliro cha 90% kuti mupeza kukula kwa 0,10 kapena kukulirapo. Koma ngati 0,10 ndiyokwera kwambiri kwa inu, sikungakhale koyenera kuyesa lingaliro lapamwamba. Kuti mukhale kumbali yotetezeka, mutha kuganiza zoyendetsa phunzirolo kuti mukhale ndi zotsatira zochepa, monga 0,05. Pankhaniyi, mudzafunika 8407 zowonera, ndiye kuti, chitsanzo chidzawonjezeka pafupifupi 4 nthawi. Koma bwanji ngati titamamatira ku kukula kwathu kwachitsanzo choyambirira, koma tiwonjezere mphamvu mpaka 0,99 kuti tikhale otetezeka ngati titapeza zotsatira zabwino? Pankhaniyi, n kwa gulu limodzi adzakhala 3676, amene kale bwino, koma kuwonjezera chitsanzo kukula ndi oposa 50%. Ndipo chifukwa chake, sitingathe kutsutsa zongopeka chabe, ndipo sitidzalandira yankho la funso lathu.
Nanga bwanji ngati titayesa lingaliro la nonferiority hypothesis m'malo mwake?
Kukula kwachitsanzo kudzawerengedwa pogwiritsa ntchito njira yomweyo kupatula denominator.
Kusiyanitsa kuchokera ku formula yomwe imagwiritsidwa ntchito poyesa hypothesis yapamwamba ndi motere:
- Z1−α/2 imasinthidwa ndi Z1−α, koma ngati muchita zonse motsatira malamulo, mumalowetsa α = 0,05 ndi α = 0,025, ndiye kuti, ndi nambala yomweyo (1,96)
- (μB−μA) ikuwoneka mu denominator
- θ (kukula kwake) kumasinthidwa ndi Δ (malire a otsika)
Ngati tilingalira kuti µB = µA, ndiye (µB − µA) = 0 ndi kuwerengera kukula kwachitsanzo kwa malire otsika ndizomwe tingapeze ngati titawerengera kukula kwa kukula kwa 0,1, kwakukulu! Titha kuchita phunziro la kukula kofanana ndi malingaliro osiyanasiyana ndi njira yosiyana yofikira, ndipo tidzapeza yankho la funso lomwe tikufunadi kuyankha.
Tsopano tiyerekeze kuti sitikuganiza kuti µB = µA ndi
Tikuganiza kuti µB ndiyoyipa pang'ono, mwina ndi mayunitsi 0,01. Izi zimawonjezera chiwerengero chathu, kuchepetsa kukula kwa chitsanzo pa gulu mpaka 1737.
Kodi chimachitika ndi chiyani ngati mtundu B uli bwino kuposa mtundu A? Timakana lingaliro lopanda pake lakuti B ndi woipa kuposa A kuposa Δ ndikuvomereza lingaliro lina lakuti B, ngati loipa, silili loipa kuposa A ndi Δ ndipo lingakhale bwino. Yesani kuyika mawu omalizawo m'njira zosiyanasiyana ndikuwona zomwe zimachitika (mwachangu, yesani). Munthawi yoyang'ana kutsogolo, palibe amene akufuna kukhazikika "osaposa Δ" moyipa komanso mwina bwino.
Pamenepa, tikhoza kuchita phunziro, lomwe limatchedwa mwachidule kwambiri "kuyesa lingaliro lakuti imodzi mwa zosankhazo ndi yopambana kapena yotsika kuposa ina." Amagwiritsa ntchito magulu awiri a hypotheses:
Seti yoyamba (mofanana ndi kuyesa malingaliro osakhala otsika):
Seti yachiwiri (mofanana ndi poyesa lingaliro lapamwamba):
Timayesa lingaliro lachiwiri pokhapokha ngati loyamba likanidwa. Tikamayesa motsatizana, timasunga mtundu wonse wa zolakwika za Type I (α). Mwachizoloŵezi, izi zikhoza kutheka popanga 95% nthawi yodalirika pa kusiyana pakati pa njira ndi kuyesa kuti mudziwe ngati nthawi yonseyi ndi yaikulu kuposa -Δ. Ngati nthawiyo sichidutsa -Δ, sitingathe kukana mtengo wamtengo wapatali ndikuyimitsa. Ngati nthawi yonseyi ndi yayikulu kuposa −Δ, tipitiliza ndikuwona ngati nthawiyo ili ndi 0.
Palinso mtundu wina wa kafukufuku womwe sitinakambirane - maphunziro ofanana.
Maphunziro amtunduwu amatha kusinthidwa ndi maphunziro osakhala apansi komanso mosemphanitsa, koma amakhala ndi kusiyana kofunikira. Mayesero osakhala apansi amafuna kusonyeza kuti njira B ndi yabwino ngati A. Kuyesa kufanana kumafuna kusonyeza kuti njira B ndi yabwino ngati A. Njira A ndi yabwino ngati B, zomwe zimakhala zovuta kwambiri. Kwenikweni, tikuyesera kudziwa ngati nthawi yonse yodalira kusiyana kwa njira ili pakati pa −Δ ndi Δ. Maphunziro otere amafunikira kukula kwachitsanzo chokulirapo ndipo samachitika pafupipafupi. Choncho nthawi ina mukadzachititsa phunziro limene cholinga chanu chachikulu ndi kuonetsetsa kuti Baibulo latsopanolo silikuipiraipirapo, musakhale ndi "kulephera kukana lingaliro lopanda pake." Ngati mukufuna kuyesa lingaliro lofunika kwambiri, ganizirani zosankha zosiyanasiyana.
Source: www.habr.com