I-Survey yoPhando yoBucwaningo ifuna ukunciphisa i-Error Sampling Error
Yiyiphi i-Interval Trust?
Ixesha lokuzithemba liyinqanaba lephutha umphandi oza kulufumana ukuba unokubuza umbuzo othile wophando , uthi, kuwo onke amalungu iluntu ekujoliswe kuwo kwaye ufumane impendulo efanayo ukuba amalungu esampuli anike kwi-survey.
Ngokomzekelo, ukuba umphandi wasebenzisa ixesha lokuzithemba lalingama-4 kunye no-60% abathathi-nxaxheba kwisesampula yesava ephendule "Ngaba uya kuncomela kubahlobo," unokuqiniseka ukuba phakathi kwama-54% kunye nama-64% amalungu kuwo wonke umntu ojoliswe kuwo Kwakhona uthi "Ngaba uncomeka kubahlobo" xa ubuzwa umbuzo ofanayo. Ixesha lokuzithemba, kulo mzekelo, ngu-+/- 4.
Yintoni iNqanaba lokuThembela?
Inqanaba lokuzithemba libonisa indlela othembekileyo umphandi angaba ngayo idatha efunyenwe kwisampuli. Amanqanaba okuzithemba aboniswa njengepesenti kwaye abonise ukuba ngaba ipesenti yoluntu ekujoliswe kuyo iyakunika impendulo ephakathi kwexesha lokuzithemba. Inqanaba lokuzithemba elisetyenziswa ngokuqhelekileyo li-95%. Umxholo ohambelana nawo ubizwa ngokuba yi-statistical value.
Ukuthembela komphenyi kwimeko yokuba isampula emele ngokwenene abantu abajoliswe kuyo ichatshazelwe ngamanani amanqaku.
Ukuzithemba komphenyi ekuqulunqweni nasekuphunyezweni kwazo - kunye nokuqaphela ukusilela kwayo - kuxhomekeka kakhulu kwizinto ezintathu eziguqukayo: ubungakanani besayizi, imvama yokuphendula kunye nobukhulu bendawo. Abaphandi baye bavuma ukuba ezi zinto zimele ziqwalaselwe ngononophelo ngexesha locwangciso lophando.
- Ubukhulu besampula Ngokuqhelekileyo, iisampuli ezinkulu zihambisa idatha ebonisa ngokwenene abantu abajoliswe kuyo. Ixesha elide lokuzithemba libonisa ukuzithemba okungaphantsi kwedatha kuba kukho umda omkhulu wephutha . Ixesha elithembekileyo lokuzithemba lifana nokuhlawula iibhenyi zakho. Nangona kukho ubudlelwane phakathi kwexesha lokuzithemba kunye nobukhulu besampula, kodwa alukho ulwalamano oluhambelanayo . Umphandi akakwazi ukunqumla inqanaba lokuzithemba kwisiqingatha ngokuphindwe kabini ubukhulu besampula.
- Ukuphindaphindwa kwempendulo Ukuchaneka kwimiba yesampula ebonisa ukuba abantu abajoliswe kuyo kuxhomekeke kwipesenti yabaphenduli abathi banike impendulo ethile okanye baphenduliwe ngendlela ethile . Uninzi lwabaphenduli abaye banike impendulo ethile, bathi "Ndonwabile kakhulu," uqinisekisile ukuba umphandi angaba yile mpendulo. Kuya kuba nokuhlukahluka kwepesenteji kwiindawo eziphakathi kwendlela eqhelekileyo. Okokuthi, ukuba umphandi u-50% uthembele ukuba amalungu ebantu abajoliswe kuwo aya kuphendulwa (ngaphakathi kwexesha lokuzithemba) njengamalungu esampula yabemi, kunokwenzeka ukuba kukho ukuhlukahluka kwinqanaba le-50%.
Kuhle ukuba ukhumbule ukuba i- outliers (idatha esekupheleni kwayo, okanye imisila, yekhalo eliqhelekileyo) liyakwenzeka ngokumalunga nomlinganiselo ofanayo kuluntu njengoko benza kwisampuli - kukho ukuhluka okuncinane apha , kuba kukho imvama ephantsi. (Cinga ukuba iibhola e-Galton Box zithatha njani phakathi kwePacific Science Centre umboniso? Iibhola ezimbalwa kuphela ezikhupha emsila.) Ngenxa yoko, kulula ukuba nethemba ngokuphindaphindiweyo kweempendulo .
- Ubuninzi boLuntu aluyinto ebalulekileyo kwisayizi yeesampuli ngaphandle kokuba umphandi usebenza nabemi abancinci kwaye baziwa kuye (umzekelo, okwaneleyo ukwenzela ukuba onke amalungu omphakathi angabonwa ngumphandi).
Iinkqubo zoPhando zoBumba zibonisa ukuba:
Iimathematika zengqondo zibonisa ukuba ubungakanani bendawo abuyiyo nto ngaphandle kokuba ubungakanani beesampulu zidlula iipesenti ezimbalwa zebonke abantu obahlolayo. Oku kuthetha ukuba isampula yabantu abangama-500 sinceda ngokulinganayo ekuhloliseni izimvo zorhulumente we-15,000,000 njengoko bekuya kuba sisixeko sama-100,000.
Ukuvelisa isampuli ummeleli ube yinkqubo ebiza ngexabiso kunye nexesha. Abaphandi bahlala bejamelana nokuhweba phakathi kwezinga lokuzithemba abanokufuna ukufumana-okanye izinga lokuchaneka abayifunayo ukufikelela-kunye nezinga lokuzithemba abanako ukufikelela.
Ubukhulu beSampula kwiPhando loPhando olululo
Uphando olufanelekileyo luhlolisiswa okanye luchazwa kwendalo kwaye alujolisi kumanani okanye ukulinganisa. Kodwa ukuxhalabisa malunga nephutha lokusampula ekuphandululeni uphando kusekho okusemthethweni. Njengomgaqo oqhelekileyo, ukuba isampula imela indawo ejoliswe kuyo, iindimu okanye iipateni ezivela kuphando ziya kubonakalisa uluntu oluninzi olunomdla kumphandi. Ukuba isampula ibini imele kwaye iqukethe ipesenteji enkulu yabantu abajoliswe kuyo, ngoko ukuzithemba ngokuchaneka kwedatha ephuma kweso sampuli kuya kuba nokuphakama.
Ukuqwala ubungakanani beSample kwiPhando loPhando
Imithetho eyahlukeneyo isebenzisana nophando oluninzi kunye nophando olulungileyo xa kuziwa ekufumaneni ubungakanani beesampula. Ngokuqhelekileyo, ukuzithemba kulwazi oluveliswe ngophando lophando lwekhwalithi, umphandi kufuneka abe nengcamango ecacileyo yokusetyenziswa kwedata. Idata ingafaka isiseko sencwadana echazayo (njengokwimeko yesifundo okanye uphando oluthile) okanye lunokusebenza kwinkqubo yokuhlolisisa ukuchonga iimpawu ezichaphazelekayo ezinokuthi zivavanywe emva koko zihlolwe izilungelelaniso kwisifundo esininzi.
Ubukhulu beSampula kwi-Suritative Surveys Research
Uphando oluninzi luhlala luquka ukuthelekiswa phakathi kwamacandelo eemarike okanye iinqununu zezentengiso. Ngenxa yokuba uphando oluninzi luqhutshwa ngamanani, ukuchonga ubungakanani besampula esinokuzikhethela buya kuba lula - kwiqela ngalinye elibalulekileyo okanye kwicandelo elithile kwisifundo, umphandi unethemba lokuphanda abathathi-nxaxheba abangama-100. Le nani incomo kwaye ayilona nto. Umphenyi weemarike uya kuqwalasela inani elithile elichanekileyo ukuchonga ubungakanani beesampulu kuphando lophando.
Xa kuqhutyelwa uphando lwemakethi yophando, injongo kukunyuka kwisampula into enokuthi ibe yinyani kwihlabathi elijoliswe kuyo. Isampula inikeza idatha engabonwa okanye eyaziwayo. Ukususela kule nkcukacha eyaziwayo okanye eyaziwayo, umphandi unokulinganisa iqondo apho ixabiso elingaziwayo okanye ipharamitha lingafumaneka kwiindawo ezijoliswe kuzo.
Uphando lophando oluthile lusekelwe kwingcamango yesiqhelo esivamile , ehambisanayo, engqondweni yomphandi, indawo ejoliswe kuyo-uluntu malunga noluphi na umphandi kufuneka alinganise kunokuba azi ngokwenene imimiselo. Isampuli esimeleyo sivumela umphandi ukuba abale - ukusuka kwidatha yesampuli - uluhlu olucatshangelwayo lwexabiso elinokuthi libandakanye ixabiso elingaziwa okanye ipharamitha enomdla. Uluhlu olulinganisiweyo lwamaxabiso lubonisa indawo kwindawo eqhelekileyo kwaye ibonakaliswe ngokuqhelekileyo njengedayimali okanye iphesenti.
I-Curual Normal kunye neMigangatho
Ijika eliqhelekileyo, elilinganayo libonakalisa ukubonakala. Makhe sijonge i-heuristic elula: Umsebenzi kwiziko lezesayensi uvumela inani elikhulu leebhola liwela phakathi kwamaphepha ama-acrylic amabili, elinye ngexesha. Yonke ibhola iwela ngolu hlobo oluphezulu phezulu kwesibonakaliso ize ihlahle phakathi kweyiphi na ehlukileyo, abahlukeneyo abahlulayo abahlula iinqwelo zeebhola xa bephumla. Emva kweeyure eziliqela, iibhola sele zenze umlo wesondo eliqhelekileyo. I-curve iyitshintsha nje encinane njengoko ibhola ngalinye elitsha lisandul 'ukushaya ubuninzi beebhola ezafika kuqala. Kodwa ngokubanzi, ijika elilinganayo liyabonakala kwaye lenzeke ngokwemvelo, elizimeleyo nayiphi na inyathelo ngababonisi bamaziko eSayensi okanye abasebenzi. Umzobo oveleleyo ukuba ifomu yeebhola ibonisa ukuba ininzi yeebhola iya kuwela ngaphakathi kwaye ihlale apho. Iibhola ezimbalwa ziza kwenza ukuba zifike kwiindawo ezide zekhava-ezinye ziyakuthi, kodwa zimbalwa kwinani.
Le ngongoma eqhelekileyo ifana nomxholo wesampuli. Ngethuba elo xesha isibonakaliso sichithwa kwaye iibhola ziphinda zivumeleke ukuba ziwele kwibhokisi laseGalton, ukucwangciswa kweentonga zeebhola kuya kuba yinto ehlukileyo nje. Kodwa ngaphezu kwexesha, umlo wekhava ayiyi kutshintsha kakhulu kwaye iphethini iya kuba yinyani.