基础统计学(英文版)

基础统计学(英文版)

Chapter11\nChapterOneWhatisStatistics?ONEUnderstandwhywestudystatistics.TWOExplainwhatismeantbydescriptivestatisticsandinferentialstatistics.THREEDistinguishbetweenaqualitativevariableandaquantitativevariable.FOURDistinguishbetweenadiscretevariableandacontinuousvariable.FIVEDistinguishamongthenominal,ordinal,interval,andratiolevelsofmeasurement.SIXDefinethetermsmutuallyexclusiveandexhaustive.GOALSWhenyouhavecompletedthischapter,youwillbeableto:2\nWhystudystatistics?NumericalinfoiseverywhereButhowdoweknowifconclusionsreportedareaccurate?StatisticaltechniquesareusedtomakedecisionsthataffectourlivesThisiswhyyoungerpeoplepaymoreforinsurance…KnowledgeofstatisticalmethodsatleasthelpsyouunderstandwhydecisionsaremadeInfutureyouwillmakedecisionsthatinvolvedata3\nWhatisMeantbyStatistics?Statisticsisthescienceofcollecting,organizing,presenting,analyzing,andinterpretingnumericaldatatoassistinmakingmoreeffectivedecisions.Incommonusagestatisticsreferstonumericalinformation…..Butinthiscoursethetermhasawidermeaning….4\nWhoUsesStatistics?Statisticaltechniquesareusedextensivelybymanagersinmarketing,accounting,qualitycontrol,consumers,professionalsportspeople,hospitaladministrators,educators,politicians,physicians,gamblers,etc...5\nTypesofStatisticsDescriptiveStatistics:Methodsoforganizing,summarizing,andpresentingdatainaninformativeway.EXAMPLE1:AGalluppollfoundthat49%ofthepeopleinasurveyknewthenameofthefirstbookoftheBible.Thestatistic49describesthenumberoutofevery100personswhoknewtheanswer.6\nTypesofStatisticsDescriptiveStatistics:Methodsoforganizing,summarizing,andpresentingdatainaninformativeway.EXAMPLE2:AccordingtoConsumerReports,GeneralElectricwashingmachineownersreported9problemsper100machinesduring2002.Thestatistic9describesthenumberofproblemsoutofevery100machines.7\nTypesofStatisticsDescriptiveStatistics:Methodsoforganizing,summarizing,andpresentingdatainaninformativeway.EXAMPLE3:TheCanadiangovernmentreportsthatthepopulationofCanadawas18,238,000in1961,21,568,000in1971,24,820,000in1981,28,031,000in1991,and31,050,700in2001.Ifwecalculatepercentagegrowthoverthedecadesitisalsodescriptivestatistics.8\nTypesofStatisticsInferentialStatistics:Themethodsusedtodeterminesomethingaboutapopulation,basedonasample.OEXAMPLE1:IntheprecedingexampleonCanadianpopulationchanges,ifyouusethepastdatatoforecastthepopulationofCanadaintheyear2021orexpectedpercentageofgrowthfrom2000to2021,thenthisisconsideredinferentialstatistics.9\nTypesofStatisticsInferentialStatistics:Themethodsusedtodeterminesomethingaboutapopulation,basedonasample.EXAMPLE2:Theaccountingdepartmentofalargefirmwillselectasampleoftheinvoicestocheckforaccuracyforalltheinvoicesofthecompany.10\nTypesofStatisticsInferentialStatistics:Themethodsusedtodeterminesomethingaboutapopulation,basedonasample.EXAMPLE3:Winetasterssipafewdropsofwinetomakeadecisionwithrespecttoallthewinewaitingtobereleasedforsale.11\nPopulationvs.SamplePopulationistheentiresetofindividualsorobjectsofinterestorthemeasurementsobtainedfromallindividualsorobjectsofinterest.Sampleisaportion,orpart,ofthepopulationofinterest12\nSeealsop.7Population:AllitemsSample:Itemsselectedfromthepopulation13\nNB:don’tconfusepopulationinstatisticswithacountry’spopulation!ApopulationmightconsistofallthepeopleinNanaimobutalsomaymeanthePEratiosforallchemicalstocks,ortotalassetsofthe20largestbanksinNorthAmerica,totalcollectionofprices,ages,squarefootageofretailspaceinNanaimo,andsoon.14\nTypesofVariablesForaQualitativeorAttributevariablethecharacteristicbeingstudiedisnonnumeric.EXAMPLES:Gender,religiousaffiliation,typeofautomobileowned,countryofbirth,eyecolourareexamples.15\nTypesofVariablesInaQuantitativevariableinformationisreportednumerically.EXAMPLES:balanceinyourchequingaccount,minutesremaininginclass,ornumberofchildreninafamily.16\nTypesofVariablesQuantitativevariablescanbeclassifiedaseitherdiscreteorcontinuous.Discretevariables:canonlyassumecertainvaluesandthereareusually“gaps”betweenvalues.EXAMPLE:thenumberofbedroomsinahouse,orthenumberofhammerssoldatthelocalHomeDepot(1,2,3,…,etc).Butyoucannothave2.3bedroomsor10.6hammers…Thusdiscretevariablesresultfromcounting.17\nTypesofVariablesAcontinuousvariablecanassumeanyvaluewithinaspecifiedrange.Examplesare:Thepressureinatire,theweightofaporkchop,ortheheightofstudentsinaclass.Typically,continuousvariablesaretheresultofmeasuringsomething.18\nSummaryofTypesofVariables19\nLevelsofMeasurementDatamaybeclassifiedintofourclassesorlevelsofmeasurement:nominal,ordinal,interval,andratio.Nominallevel:Datathatisclassifiedandcounted.EXAMPLES:eyecolour,gender,religiousaffiliation.20\nLevelsofMeasurementMutuallyexclusive:Anindividual,object,ormeasurementisincludedinonlyonecategory.Exhaustive:Eachindividual,object,ormeasurementmustappearinoneofthecategories.Nominaldatahavenoparticularorderorrankandaremutuallyexclusive.21\nMaritalStatus2000(population15yearsandolder)StatusNumberSingle(nevermarried)7,285,560Married(legally,separated,common-law)14,614,564Divorced1,452,000Widowed1,527,075Total24,879,199Thesedataareanominallevelofmeasurementbecauseitcanonlybeclassifiedintoclassesandtheorderofthemaritalstatusisnotimportant.Theclassesarealsomutuallyexclusiveandexhaustive.22\nLevelsofMeasurementOrdinallevel:involvesdataarrangedinsomeorder,butthedifferencesbetweendatavaluescannotbedeterminedoraremeaningless.EXAMPLE:Duringatastetestof4softdrinks,MountainDewwasrankednumber1,Spritenumber2,Seven-upnumber3,andOrangeCrushnumber4.23\nLevelsofMeasurementIntervallevelissimilartotheordinallevel,withtheadditionalpropertythatmeaningfulamountsofdifferencesbetweendatavaluescanbedetermined.Thereisnonaturalzeropoint.EXAMPLE:TemperatureontheCelsiusscale.0degreesdoesnotrepresenttheabsenceoftemperature,justthatitiscold!24\nLevelsofMeasurementRatiolevelistheintervallevelwithaninherentzerostartingpoint.Differencesandratiosaremeaningfulforthislevelofmeasurement.EXAMPLES:Monthlyincomeofsurgeons,ordistancetraveledbymanufacturer’srepresentativespermonth.25\n26\n27\n28\n29\n30