r:\fcs\oc\h125\im2cours\mktrsch\mrprac.doc5/4/20255/4/2025PRACTICEAIDSAMPLESELECTIONMETHODSTypeofSamplingDescriptionAdvantagesDisadvantagesA.Assigntoeachpopulationmemberauniquenumber;selectsamplebyuseofatableofrandomnumbers.Requiresminimumknowledgeofpopulationinadvance.Simplestofallsamplingmethods.Easytoconduct,analyzedata,andcomputeerrors.Doesnotmakeuseofknowledgeofpopulationwhichresearchermayhave.Largererrorsforsamesamplesizethaninstratifiedsampling.B.Subdividethepopulationintosubgroups;randomlyselectgivennumberofrespondentsfromeachsubgroup.Assuresrepresentativeswithrespecttocharacteristicwhichformsbasisofclassifyingunits;therefore,yieldslessvariabilitythanA.Decreaseschanceoffailingtoincludeadequatenumbersofpopulationsegmentsbecauseofclassificationprocess.Characteristicsofeachsubgroupcanbeestimated,andhencecomparisonscanbemade.Requiresaccurateinformationonproportionofpopulationineachsubgroup,otherwiseincreaseserror.165392MR-106/92MarketResearchr:\fcs\oc\h125\im2cours\mktrsch\mrprac.doc5/4/20255/4/2025Ifstratifiedlistsarenotavailable,maybecostlytopreparethem;possibilityoffaultyclassificationandhenceincreaseinvariability.OftenrequireslargersamplesizethanA.Needatleast20peopletomakestatisticalcomparisonsmeaningful.165392MR-206/92MarketResearchr:\fcs\oc\h125\im2cours\mktrsch\mrprac.doc5/4/20255/4/2025TypeofSamplingDescriptionAdvantagesDisadvantagesC.Selectgroups/clustersofrespondentsbysomeformofrandomsampling;surveyallindividualswhoaremembersoftheseunits.Ifclustersaregeographicallydefined,yieldslowestfieldcosts.Requireslistingonlyindividualsinselectedclusters.Characteristicsofclustersaswellasthoseofpopulationcanbeestimated.Canbeusedforsubsequentsamples,sinceclusters,notindividuals,areselected,andsubstitutionofindividualsmaybepermissible.Largererrorsforcomparablesizethanotherprobabilitysamples.Requiresabilitytoassigneachmemberofpopulationuniquelytoacluster;inabilitytodosomayresultinduplicationoromissionofindividuals.D.Usenaturalorderingororderpopulation:selectrandomstartingpoint;selectitemsatintervalofnearestintegertosamplingratio.Ifpopulationisorderedwithrespecttopertinentcharacteristics,givesstratificationeffect,andhencereducesvariabilitycomparedtoA.Simplicityofdrawingsample;easytocheck.Ifsamplingintervalisrelatedtoaperiodicorderingofthepopulation,increasedvariabilitymaybeintroduced.Estimatesoferrorlikelytobehighwherethereisstratificationeffect.165392MR-306/92MarketResearchr:\fcs\oc\h125\im2cours\mktrsch\mrprac.doc5/4/20255/4/2025E.Selectionbasedonwhoisavailable.Itisconvenient.Usuallyveryunconvincingtoclientandotherusers.Cancontainagreatdealofbias.165392MR-406/92MarketResearchr:\fcs\oc\h125\im2cours\mktrsch\mrprac.doc5/4/20255/4/2025TypeofSamplingDescriptionAdvantagesDisadvantagesF.Selectingrespondentsbasedonpersonaljudgement.Canproduceacrediblesample.Cangethighquality,detailedinformation.Samplecanbeverybiasedduetopoorjudgement.Maybedifficulttogeneralizeresults.165392MR-506/92MarketResearch
