商务统计学（第7版）英文ppt课件7 Sampling Distributions、8 Confidence Interval Estimation .ppt

SamplingDistributionsChapter7

ObjectivesInthischapter,youlearn:TheconceptofthesamplingdistributionTocomputeprobabilitiesrelatedtothesamplemeanandthesampleproportionTheimportanceoftheCentralLimitTheorem

SamplingDistributionsAsamplingdistributionisadistributionofallofthepossiblevaluesofasamplestatisticforagivensamplesizeselectedfromapopulation.Forexample,supposeyousample50studentsfromyourcollegeregardingtheirmeanGPA.Ifyouobtainedmanydifferentsamplesofsize50,youwillcomputeadifferentmeanforeachsample.WeareinterestedinthedistributionofallpotentialmeanGPAswemightcalculateforanysampleof50students.DCOVA

DevelopingaSamplingDistributionAssumethereisapopulation…PopulationsizeN=4Randomvariable,X,

isageofindividualsValuesofX:18,20,

22,24(years)ABCDDCOVA

.3.2.1018202224ABCDUniformDistributionP(x)x(continued)SummaryMeasuresforthePopulationDistribution:DevelopingaSamplingDistributionDCOVA

16possiblesamples(samplingwithreplacement)Nowconsiderallpossiblesamplesofsizen=2(continued)DevelopingaSamplingDistribution16SampleMeans1stObs2ndObservation182022241818,1818,2018,2218,242020,1820,2020,2220,242222,1822,2022,2222,242424,1824,2024,2224,24DCOVA

SamplingDistributionofAllSampleMeans181920212223240.1.2.3P(X)XSampleMeansDistribution16SampleMeans_DevelopingaSamplingDistribution(continued)(nolongeruniform)_DCOVA

SummaryMeasuresofthisSamplingDistribution:DevelopingASamplingDistribution(continued)DCOVANote: Herewedivideby16becausethereare16 differentsamplesofsize2.

ComparingthePopulationDistribution

totheSampleMeansDistribution181920212223240.1.2.3P(X)X18202224ABCD0.1.2.3PopulationN=4P(X)X_SampleMeansDistributionn=2_DCOVA

Sample