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1、1DataCharacteristicsDataconsistsofobservationsacrossdifferenttypesofvariables,anditisvitalthatanyDataAnalystunderstandstheseintricaciesattheearlieststageofexposuretostatisticalanalysis.Thischapterrecognizestheimportanceofdataandbeginswithatemplateofadummyquestionnaireandthen
2、proceedswiththenitty-grittiesofthesubject.Wethenexplainhowuncertaintycreepsintothedomainofcomputerscience.Thechaptercloseswithcoverageofimportantfamiliesofdiscreteandcontinuousrandomvariables.Wewillcoverthefollowingtopics:Identificationofthemainvariabletypesasnominal,categor
3、ical,andcontinuousvariablesTheuncertaintyarisinginmanyrealexperimentsRinstallationandpackagesThemathematicalformofdiscreteandcontinuousrandomvariablesandtheirapplicationsDataCharacteristicsQuestionnaireanditscomponentsThegoalofthissectionisintroductionofnumerousvariabletypes
4、atthefirstpossibleoccasion.Traditionally,anintroductorycoursebeginswiththeelementsofprobabilitytheoryandthenbuildsuptherequisitesleadingtorandomvariables.Thisconventionisdroppedinthisbookandwebeginstraightawaywithdata.Thereisaprimaryreasonforchoosingthispath.Theapproachbuild
5、sonwhatthereaderisalreadyfamiliarwithandthenconnectsitwiththeessentialframeworkofthesubject.Itisverylikelythattheuserisfamiliarwithquestionnaires.Aquestionnairemaybeaskedafterthebirthofababywithaviewtoaidthehospitalinthestudyabouttheexperienceofthemother,thehealthstatusofthe
6、baby,andtheconcernsofimmediateguardiansofthenewborn.Amulti-storedepartmentmayinstantlyrequestthecustomertofillinashortquestionnaireforcapturingthecustomer'ssatisfactionafterthesaleofaproduct.Acustomer'ssatisfactionfollowingtheserviceoftheirvehicle(seethedetailedexamplediscus
7、sedlater)canbecapturedthroughafewqueries.Thequestionnairesmayariseindifferentformsthanjustmerelyonpaper.Theymaybesentviae-mail,telephone,shortmessageservice(SMS),andsoon.Asanexample,onemayreceiveanSMSthatseeksamandatoryresponseinaYes/Noform.Ane-mailmayarriveintheOutlookinbox
8、,whichrequirestherecipienttorespondthroughavoteforanyofthesethreeoptions,"W