统计学第二章.ppt

DescribingData:

FrequencyTables,Frequency

Distributions,andGraphicPresentationChapter2

GOALSOrganizequalitativedataintoafrequencytable.Presentafrequencytableasabarchartorapiechart.Organizequantitativedataintoafrequencydistribution.Presentafrequencydistributionforquantitativedatausinghistograms,frequencypolygons,andcumulativefrequencypolygons.2

BarCharts3

PieCharts4

PieChartUsingExcel5

FrequencyDistribution AFrequencydistributionisagroupingofdataintomutuallyexclusivecategoriesshowingthenumberofobservationsineachclass.6

FrequencyTable7

RelativeClassFrequenciesClassfrequenciescanbeconvertedtorelativeclassfrequenciestoshowthefractionofthetotalnumberofobservationsineachclass.Arelativefrequencycapturestherelationshipbetweenaclasstotalandthetotalnumberofobservations.8

FrequencyDistributionClassmidpoint:Apointthatdividesaclassintotwoequalparts.Thisistheaverageoftheupperandlowerclasslimits.Classfrequency:Thenumberofobservationsineachclass.Classinterval:Theclassintervalisobtainedbysubtractingthelowerlimitofaclassfromthelowerlimitofthenextclass. 9

EXAMPLE–CreatingaFrequencyDistributionTableMs.KathrynBallofAutoUSAwantstodeveloptables,charts,andgraphstoshowthetypicalsellingpriceonvariousdealerlots.Thetableontherightreportsonlythepriceofthe80vehiclessoldlastmonthatWhitnerAutoplex.10

ConstructingaFrequencyTable-ExampleStep1:Decideonthenumberofclasses. Ausefulrecipetodeterminethenumberofclasses(k)isthe“2tothekrule.”suchthat2kn. Therewere80vehiclessold.Son=80.Ifwetryk=6,whichmeanswewoulduse6classes,then26=64,somewhatlessthan80.Hence,6isnotenoughclasses.Ifweletk=7,then27128,whichisgreaterthan80.Sotherecommendednumberofclassesis7.Step2:Determinetheclassintervalorwidth. The