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1、Part1GatheringandExploringData(descriptivestatistics)DifferentTypesofData(2.1)VariableAvariableisanycharacteristicobservedonthesubjectsinastudy.Examples:Maritalstatus,Height,Weight,IQ,Sqft,Price,NE.AvariablecanbeclassifiedaseitherCategorical(inCategories),orQuantitative(Numerical)Ava
2、riablecanbeclassifiedascategoricalifeachobservationbelongstooneofasetofcategories:Examples:Gender(MaleorFemale)ReligiousAffiliation(Catholic,Jewish,…)TypeofResidence(Apartment,Condo,…)BeliefinLifeAfterDeath(YesorNo)NE(Locatedinnortheastsectorofcity(1)ornot(0))Avariableiscalledquantit
3、ativeifobservationsonittakenumericalvaluesthatrepresentdifferentmagnitudesofthevariable.Examples:Age,NumberofSiblings,AnnualIncome,Sellingprice,SqftDiscreteversuscontinuousquantitativevariablesAquantitativevariableisdiscreteifitspossiblevaluesformasetofseparatenumbers,suchas0,1,2,3,
4、…ThesetofpossiblevaluesisnotdenseExamples:oNumberofpetsinahouseholdoNumberofchildreninafamilyoNumberofforeignlanguagesspokenbyanindividualAquantitativevariableiscontinuousifitspossiblevaluesformanintervalThesetofpossiblevaluesisdenseExamples:oHeight/WeightoAgeoBloodpressureExercis
5、eIdentifythevariabletype1.Numberofsiblingsinafamily2.Countyofresidence3.Distance(inmiles)ofcommutetoschool4.Maritalstatus5.Lengthoftimetotakeatest6.Numberofpeoplewaitinginline7.Numberofspeedingticketsreceivedlastyear8.Yourdog’sweightProportion&Percentage(RelativeFrequencies)Thepropor
6、tionoftheobservationsthatfallinacertaincategoryisthefrequency(count)ofobservationsinthatcategorydividedbythetotalnumberofobservationsFrequencyofthatcategorySumofallfrequenciesThepercentageistheproportionmultipliedby100ProportionsandpercentagesarealsocalledrelativefrequenciesExampleTa
7、bleclassifiesthe630parliamentaryseatsoftheItalianchamberofdeputiesbycoalition(2013elections).CoalitionSeatsFreq.Prop.Perc.PierluigiBersani3450.54854.8SilvioBerlusconi1250.19819.8BeppeGrillo1090.17317.3MarioMonti470.0757.46Valleed'Aoste10.0020.16MAIAE20.0030.32USEI10.0020.16AntonioIng
8、roia000Total
