## 3.4 Ubani ukubuza

Amasampula Amathuba namasampula non-ematfuba akuzona ukuthi letehlukene umkhuba; ezimweni zombili, kungcono konke mayelana izisindo.

Isampula luyisisekelo Survey Research. Abacwaningi cishe never ukubuza imibuzo yabo ukuze wonke umuntu target labantu babo. Kule ndaba, uthi izinhlolo-vo Akubona. Ucwaningo oluningi, ngandlela-thile, kuhilela sampling. Ngezinye izikhathi lokhu sampling kwenziwa ngendlela eyingcaca by umcwaningi; ezinye izikhathi kwenzeka ngokuphelele. Ngokwesibonelo, umcwaningi eyehlayo experiment laboratory abafundi undergraduate e university wakhe iye yaba isampula. Ngakho, izibonelo zalokho kuyinkinga okhuphuka kuyo yonke le ncwadi. Empeleni, omunye ukukhathazeka ezivamile engikuzwa ngawe ubudala imithombo digital lwedatha "abawona omele." Njengoba sizobona kule ngxenye, lokhu okukhathazayo mabi kancane futhi ezicashile ezingaphezu kuka abagxeki abaningi abakucabangayo. Eqinisweni, mina nguye unelungelo lokunquma ukuthi wonke welithi "representativeness" kasisizi becabanga mayelana amasampula okungenzeka kanye non-ematfuba. Kunalokho, isihluthulelo cabanga ukuthi idatha eqoqwe nokuthi noma yiluphi ukucwasana kuleyo iqoqo idatha kungenziwa sihlehliswe lapho senza tilinganiso.

Okwamanje, okuyizona theory ndlela nokulinganiswa kuyinto ematfuba sampling. Lapho idatha lubuthwa nge ematfuba izibonelo zalokho indlela esiye ababulawa ngokuphelele, abacwaningi bakwazi isisindo idatha zabo okusekelwe endleleni ukuthi zathathwa ukuba basho lezo zilinganiso engachemile mayelana labantu target. Nokho, ephelele ematfuba ukusampula ngokuyisisekelo akwenzeki emhlabeni wangempela. Kukhona ngokuvamile izinkinga ezimbili eziyinhloko 1) umehluko phakathi labantu target kanye labantu uhlaka 2) non-Ukusabela (Yilezi ncamashi izinkinga ukuthi yaphahlazeka the Literary Digest poll). Ngakho, esikhundleni sokuba acabangele ematfuba izibonelo zalokho njengesibonelo ofanele walokho empeleni okwenzeka emhlabeni, kungcono sicabange ematfuba izibonelo zalokho njengoba eziwusizo, imodeli abstract, sifana indlela yemvelo icabange ibhola frictionless kweqa phansi ngokungenamkhawulo eside ummango.

Ehlukile Ematfuba ukusampula non-ematfuba sampling. Umehluko omkhulu phakathi okungenzeka kanye non-ematfuba ukusampula ukuthi nge ematfuba izibonelo zalokho wonke umuntu emphakathini has a Amathuba ezaziwayo iinthombe. Zikhona, eqinisweni, izinhlobo eziningi non-ematfuba izibonelo zalokho, futhi lezi zindlela yokuqoqa idatha kuvama kakhulu yobudala digital. Kodwa, non-ematfuba izibonelo zalokho unedumela esabekayo phakathi ososayensi bezenhlalo futhi labantu. Empeleni, non-ematfuba izibonelo zalokho lihlotshaniswa ezinye ukwehluleka esimangalisa kunazo inhlolovo abacwaningi, ezifana Literary Digest fiasco (esisanda kuxoxa ngazo) kanye isibikezelo okungelona iqiniso US wokhetho lobumengameli of 1948 ( "Dewey unqoba Truman") (Mosteller 1949; Bean 1950; Freedman, Pisani, and Purves 2007) .

Nokho, isikhathi sivuma ukuba aphinde acabange non-okungenzeka izibonelo zalokho ngenxa yezizathu ezimbili. Okokuqala, amasampula ematfuba baye baba nzima ukwenza in umkhuba, umngcele ophakathi amasampula okungenzeka kanye amasampula non-okungenzeka is ukufiphala. Lapho kukhona yamazinga aphezulu okungabi non-Ukusabela (njengoba kukhona vo real manje), ematfuba langempela of inclusions for wabaphenduli Awaziwa, futhi ngaleyo ndlela, amasampula ematfuba namasampula non-okungenzeka akuzona abahlukile njengoba abacwaningi abaningi bakholelwa. Eqinisweni, njengoba sizobona ngezansi, kokubili lusondela ngokuyisisekelo sincike okufanayo ukulinganisa indlela: post-babhekane nezinga elikhulu. Okwesibili, kuye kwaba nentuthuko eziningi kuleli qoqo kanye nokuhlaziywa amasampula non-ematfuba. Lezi zindlela zihlukile anele izindlela ukuthi kwabangela izinkinga esikhathini esidlule ukuthi ngicabanga kunengqondo ukucabanga kwaso ngokuthi "non-Amathuba sampling 2.0." Akufanele sibe nenzondo engenangqondo izindlela non-ematfuba ngenxa yeziphambeko ukuthi kwenzeka kudala.

Okulandelayo, ukuze senze lokhu agumenti ukhonkolo xaxa, mina uzubuyekeza standard ematfuba izibonelo zalokho nokulinganisa (Isigaba 3.4.1). Umqondo esiyinhloko siwukuthi indlela eqoqwe idatha yakho kufanele usithinte kanjani wenze tilinganiso. Ikakhulu, uma wonke umuntu akanawo ematfuba olufanayo iinthombe, khona-ke wonke umuntu akufanele abe isisindo esifanayo. Ngamanye amazwi, uma ukusampula wakho awukona ebusa ngentando yeningi, khona-ke ukulinganisa wakho akufanele ngentando yeningi. Ngemva kokubukeza esabiweko, ngizobuya ukuchaza tindlelanchubo ezimbili kuya non-okungenzeka izibonelo zalokho: lowo ligxile silinganiso ukubhekana nenkinga idatha ngobudlabha eqoqwe (Isigaba 3.4.2), kanti lowo ezama ukubeka ukulawula indlela idatha eqoqwe (Isigaba 3.4.3). I-agumenti in umbhalo main izochazwa ngezansi ngamazwi kanye netitfombe; abafundi ungathanda ukwelashwa zezibalo okwengeziwe kufanele futhi bheka isithasiselo lobuchwepheshe.