Luotettavuus

Määritelmä

Reliabilityisreliability,whichreferstothedegreetowhichtheresultsobtainedareconsistentwhenthesamemethodisusedtorepeatedlymeasurethesameobject.Ontheotherhand,reliabilityreferstothereliabilityofmeasurementdata.

Forexample,forthefirstquestionofthefirstpartofthe"LibraryUtilizationandSatisfactionQuestionnaire",ifyouaskthesamequestion3daysapartfromthesameperson,ifyouansweritforthefirsttime,youwillbeTheinvestigatorchoosesA,thesecondanswerchoosesC,andthethirdanswerchoosesD,whichmeansthatthereliabilityofthesurveyresultsforthisquestionislow,becausethesurveyresultsarequitedifferent.Ifthesameanswerisselectedthreetimesortheanswerwithsmalldifferencesisselected,itmeansthatthereliabilityofthesurveyresultsishighundertheconditionofexcludingsystematicerrors.

Kaava

Ifisusedtoindicatethetruevalue,indicatesthatthedeviationisthesystematicerror,

representstherandomerrorofthemeasurement,representsthemeasurementresult,thereare:

Intheabovedecompositionformula,

isanabstractvariable,apotentialvaluethatneedstobeestimated.Systemerrorisanerrorthatcanbeavoidedorreducedbyadoptingcertainmeans,whilerandomerrorisunavoidable.

Jos mitattu tulos on yhteneväinen todellisen arvon kanssa tai ero on pieni, mittauksen on oltava "luotettava" tai "luotettava". Muuten mittauksen on oltava "epäluotettava" tai "epäluotettava" jossain määrin.

Becausethesystematicerrorisdifficulttodecompose,andthequestionnairedesignrequirestoavoidsystematicerrorsasmuchaspossible,sousuallyonlyrandomerrorsareconsideredinthereliabilityanalysis.Thatis,onthebasisofthefollowingformula,analyzethereliabilityofthequestionnaire:

Luotettavuuskerroin

Yleiskatsaus

Forrandomerrors,itisgenerallyassumedthattheexpectedvalue(averagevalue)is0andisindependentofthetruevalue.Underthisassumption,thereare:

Sinceandareindependentofeachother,therearethefollowingformulas:

VisiblemeasurementvaluesThevarianceisequaltothesumofthetruevaluevarianceandtheerrorvariance,andandTherelativesizeofcanbeusedtodescribethecredibilityofthesurveyresults.Thelargerthemeasurement,thelargertherandomerrorandthelowerthereliabilityofthemeasurement.Weusethereliabilitycoefficienttoexpressthedegreeofreliability.

Määritelmä

Thereliabilitycoefficientofthequestionnaireisdefinedas:thevarianceofthetruevaluethevarianceofthemeasuredvalue

,thatis,

ordefinedas:

Thelarger,Indicatingthegreaterthecredibilityofthequestionnaire.

Haitat

Fromtheabovereliabilitycalculationformula,asitinvolvesthesumofsquaresoferrors,itisnecessarytorepeatmultipletimesforthesamesurveyobject.Measurement,onthebasisofestimatingthevalues​​ofand,thereliabilityestimatecanbeobtained.However,multipleretestswillbringaboutmemoryeffectandconnectioneffect,andwillcauseobjectiontothesurveyed,soitismoredifficulttoachieveinsurveyresearch.

Luotettavuuden arviointi

Beforeestimatingthereliabilityofthequestionnaire,itisnecessarytouseanappropriatescale(suchasLikertscale)toAllkindsofsubjectiveorobjectivealternativeanswersintheareconvertedintodigitalform,andthenthequestionnaireisscoredonthisbasis(includingindividualscores,groupscoresofrelatedtopics,andtotalscores,etc.).

Thecommonlyusedspecificmethodsofreliabilityanalysisincludetest-retestreliability,duplicatereliability,split-halfreliability,andreliabilitycoefficientmethods(thelattertwocanbeclassifiedasSisäinen johdonmukaisuusluotettavuus).

Testaa-testaa uudelleen luotettavuus

Testaa-testaa uudelleen luotettavuus(test-retestreliability)isalsocalledtest-retestreliability.Itusesthesamequestionnaireforthesamegroupofrespondents.Thesurveywasconductedtwiceatdifferenttimepoints,andthedegreeofdifferencebetweenthetwosurveyresults.Thetest-retestreliabilityreflectstheinfluenceofrandomerrors.

Thesourceoftheerrorexaminedinthetest-retestreliabilityistherandominfluencebroughtaboutbythechangeoftime.Whenassessingthereliabilityofretests,wemustpayattentiontothetimebetweenretests.Forpersonalitytests,theintervalbetweenretestsisbetweentwoweeksandsixmonths.

Whenevaluatingtest-retestreliability,youshouldalsopayattentiontothefollowingtwoimportantissues:(1)Testaa-testaa uudelleen luotettavuusgenerallyonlyreflectschangescausedbyrandomfactors,anddoesnotreflectlong-termchangesinsubjects’behavior.⑵Differentbehaviorsareaffecteddifferentlybyrandomerrors.

Disadvantage:Retestreliabilityhasadilemma.Shorteningthetimeintervalbetweentwotestsmakesiteasierforthesubjecttorecallthetestquestions;whileextendingthetimeintervalbetweenthetwotests,thesubjectismoresusceptibletochangesinexternalinfluences.

Rinnakkaismuodot Luotettavuus

Rinnakkaismuodot Luotettavuus,alsoknownasequivalencecoefficient,isakindofEquivalenceReliability,Referstothedegreeofvariationofthequestionnairesurveyresultscomparedtoanotherverysimilarquestionnairesurveyresult.Itusestwoquestionnaireswithequivalentcontentbutdifferenttopicsforthesamegroupofrespondents,andthencomparesthedegreeofcorrelationbetweenthetwosetsofdata.

Itismoreworkloadthanretestingreliability,becausethesamemeasurementtool(questionnaire,mentalscale,etc.)needstoconstructtwoequivalentcopies,andthetwocopiesshouldcontainthesameamount,Type,content,difficultyofthetopic.Toassessthereliabilityofacopy,twocopiesareusedtotestthesamegroupofsubjects,andthenthecorrelationcoefficientofthemeasurementscoresofthetwocopiesisestimated.Thelargerthecorrelationcoefficient,thesmallerthevariationcausedbythecompositionofthetwocopies.Thisisdifferentfromthevariationcausedbyconsideringtimeinthereliabilityofretestingstability.Thatistosay,thecorrelationcoefficientreflectsthedegreeofequivalenceofthemeasuredscores,sothereplicareliabilityisalsocalledtheequivalencereliability.

Themainadvantagesofreplicareliabilityare:⑴Itcanavoidsomeproblemsofretestreliability,suchasmemoryeffect,practiceeffect,etc.;⑵Suitableforlong-termfollow-upresearchorinvestigationofsomeinterferencevariablesonthetestAchievementimpact;⑶reducethepossibilityofcounselingorcheating.☆Thelimitationsofreplicareliabilityare:(1)Ifthemeasuredbehaviorissusceptibletopractice,thereplicareliabilitycanonlybereducedbutnoteliminated;(2)thenatureofsometestswillchangeduetorepetition;(3)someItisdifficulttofindasuitablecopyofthetest.

Sisäinen johdonmukaisuusluotettavuus

Itmainlyreflectstherelationshipbetweentheinternalquestionsofthetest,andexamineswhethereachitemofthetestmeasuresthesamecontentorcharacteristics.Sisäinen johdonmukaisuusluotettavuusisdividedintohalf-halfreliabilityandhomogeneityreliability.

1,Split-halfreliability(split-halfreliability)referstothedegreeofvariationintheresultsofthetwohalvesofthequestionnaireinasurvey.isthereliabilitycoefficientobtainedbydividingthetestintotwohalvesandcalculatingthecorrelationbetweenthetwohalvesofthetest.Thelongerthetest,thehigherthereliabilitycoefficient.ThecorrectionformulaistheSpearman-Brownformula.Spearman-Brownformulaisanempiricalformulaforcorrectingsplit-halfreliability(rtt=2rhh/(1+rhh)Generallyspeaking,ifthetestisdividedintotwohalves,thesplittingcoefficientrttis0.5)

Itshypothesisisthatthevarianceofthetestscoresinthetwohalvesareequal.Whenthehypothesisisnotvalid,oneoftheFlanaganformulaorthekulonformulacanbeusedtodirectlyobtainthereliabilitycoefficientofthetest.

2,Homogeneityreliabilityreferstotheextenttowhicheachiteminthetestexaminesthesamecontent.Whenthereliabilityofhomogeneityislow,eventhougheachtestitemseemstomeasurethesametrait,thetestisactuallyheterogeneous,thatis,thetestmeasuresmorethanonetrait.Thehomogeneityanalysisissimilartotheinternalconsistencyanalysisintheprojectanalysis.Severalformulasforcalculatinghomogeneityreliability:(1)Kudd-Richardsonformula(2)Cronbachalphacoefficient.Forsomecomplexandheterogeneouspsychologicalvariables,itisnotfeasibletouseasinglehomogeneitytest,soseveralrelativelyheterogeneoussubtestsareoftenused.

Raterreliability

referstotheconsistencyofdifferentratersinevaluatingthesameobject.Thesimplestestimationmethodistorandomlyselectanumberofanswersheets,scorethembytwoindependentraters,andthenfindthecorrelationcoefficientofthetwojudgescoresforeachanswersheet.Thecalculationofthiscorrelationcoefficientcanusetheproduct-differencecorrelationmethod,ortheSpearmanrankcorrelationmethod.

Luotettavuuden ja kelvollisuuden välinen suhde

Therearenotonlyobviousdifferencesbetweenthereliabilityandvalidityofthequestionnaire,buttherearealsomutualconnectionsandmutualconstraints.Reliabilitymainlyanswersquestionsaboutconsistency,stabilityandreliabilityofmeasurementresults;validitymainlyanswersquestionsaboutvalidityandcorrectnessofmeasurementresults.

TherelationshipbetweenvalidityandreliabilitycanbeunderstoodbytheformulaO=TSRthatconstitutesthemeasuredvalue.Ifthemeasurementiscompletelyvalid,thatis,0=T,S=0,R=0,themeasurementmustbecompletelycredibleatthistime.Ifthereliabilityofthescaleisinsufficient,itmaynotbecompletelyvalid,becauseO=TR.Ifthescaleiscompletelycredible,itcanbecompletelyeffective,oritmaynotbe,becausetheremaybeerrorsthatmayleadtoerrors.Althoughlackofreliabilitynecessarilylacksvalidity,thedegreeofreliabilitydoesnotreflectthedegreeofvalidity.Reliabilityisanecessaryconditionforvalidity,butnotasufficientcondition.Fromatheoreticalpointofview,thequantityshouldhavesufficientvalidityandreliability;fromapracticalpointofview,agoodscaleshouldalsobepractical.Practicalityreferstotheeconomy,convenienceandinterpretabilityofthescale.

Generallyspeaking,reliabilityisanecessaryconditionforvalidity,thatis,validitymustbeestablishedonthebasisofreliability;butthereisnomeasureofvalidity,evenifitsreliabilityishigh,Suchameasurementisalsomeaningless.Luotettavuuden ja kelvollisuuden välinen suhdehasthefollowingtypes:

①Uskottava ja tehokas

Thiskindofquestionnaireaccuratelyreflectsthetrueattitudeofthesurveyedperson.ThequestioninthequestionnaireisCloselyrelatedtothetargetoftheinvestigation.ThissituationisshowninFigure8-8(a).Thesolidpoint(x,y)inthefigurerepresentsthetruesituationofthephenomenontobemeasured,andtheremainingpointsrepresentthemeasurementresultsobtainedafterinvestigation.Ifthesurveyresultscantrulyreflectthesurveyedobjectsandthemeasurementerrorissmall,itmeansthattheresultsofthequestionnairesurveyarecredibleandeffective.

② Luotettava mutta virheellinen

Althoughtheresultsofthiskindofquestionnairecanaccuratelyreflectthetrueattitudesoftherespondents,thequestionnairehasaweakcorrelationwiththerealpurposeofthesurvey,Inconsistentwiththeobjectivesoftheinvestigation.AsshowninFigure8-8(b).Thissituationshowsthatalthoughtheresultsobtainedinthesurveyarecredible,theremaybeerrorsinsomelinks.Forexample,thedesignofthequestionsinthequestionnairecausedallthesurveyedpersonneltohaveadeviationinunderstanding,whichresultedinasystem.Sexualdeviation.

③Epäluotettava ja virheellinen

Inthiscase,theresultsofstatisticalsurveysarescattered,anditisdifficulttoobtaineffectiveresultsfromthequestionnaires.Thisisthemeasurementapplication.Typestoavoid.AsshowninFigure8-8(c).