Copyright©2009CengageLearning1.1ChapterFiveDataCollectionandSamplingCopyright©2009CengageLearning5.2Recall…Statisticsisatoolforconvertingdataintoinformation:DataStatisticsInformationButwherethendoesdatacomefrom?Howisitgathered?Howdoweensureitsaccurate?Isthedatareliable?Isitrepresentativeofthepopulationfromwhichitwasdrawn?Thischapterexploressomeoftheseissues.Copyright©2009CengageLearning5.3MethodsofCollectingData…Therearemanymethodsusedtocollectorobtaindataforstatisticalanalysis.Threeofthemostpopularmethodsare:•Directobservation(E.g.Numberofcustomersenteringabankperhour)•Experiments(E.g.newwaystoproducethingstominimizecosts)•SurveysCopyright©2009CengageLearning5.4Surveys…Asurveysolicitsinformationfrompeople;e.g.Galluppolls;pre-electionpolls;marketingsurveys.TheResponseRate(i.e.theproportionofallpeopleselectedwhocompletethesurvey)isakeysurveyparameter.Surveysmaybeadministeredinavarietyofways,e.g.•Personalinterview,•Telephoneinterview•Self-administeredquestionnaireCopyright©2009CengageLearning5.5QuestionnaireDesign…Overtheyears,alotofthoughthasbeenputintothescienceofthedesignofsurveyquestions.Keydesignprinciples:1.Keepthequestionnaireasshortaspossible.2.Askshort,simple,andclearlywordedquestions.3.Startwithdemographicquestionstohelprespondentsgetstartedcomfortably.4.Usedichotomous(yes|no)andmultiplechoicequestions.5.Useopen-endedquestionscautiously.6.Avoidusingleading-questions.7.Pretestaquestionnaireonasmallnumberofpeople.8.Thinkaboutthewayyouintendtousethecollecteddatawhenpreparingthequestionnaire.Copyright©2009CengageLearning5.6Sampling…Recallthatstatisticalinferencepermitsustodrawconclusionsaboutapopulationbasedonasample.Sampling(i.e.selectingasub-setofawholepopulation)isoftendoneforreasonsofcost(it’slessexpensivetosample1,000televisionviewersthan100millionTVviewers)andpracticality(e.g.performingacrashtestoneveryautomobileproducedisimpractical).Inanycase,thesampledpopulationandthetargetpopulationshouldbesimilartooneanother.Copyright©2009Cengage...
