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ID:12589423
大小:1.54 MB
页数:55页
时间:2018-07-17
《chap 5 the normal distribution & sampling distributions:第一章5正态分布与抽样分布》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、ImportanceofNormalDistributionDescribesmanyrandomprocessesorcontinuousphenomenaCanbeusedtoapproximatediscreteprobabilitydistributionsBinomialPoissonBasisforclassicalstatisticalinferenceNormalDistribution‘Bell-shaped’&symmetricalMean,median,modeareequal‘Middlespread’is1.33sRandomvariableh
2、asinfiniterangeMeanMedianModeStandardizetheNormalDistributionOnetable!NormalDistributionStandardizedNormalDistributionStandardizingExampleNormalDistributionStandardizingExampleNormalDistributionStandardizedNormalDistributionObtainingtheProbability.0478.020.1.0478StandardizedNormalPro
3、babilityTable(Portion)ProbabilitiesShadedareaexaggeratedExampleP(3.8£X£5)ExampleP(3.8£X£5)NormalDistribution.0478StandardizedNormalDistributionShadedareaexaggeratedExampleP(2.9£X£7.1)ExampleP(2.9£X£7.1)NormalDistribution.1664.0832.0832StandardizedNormalDistributionShadedareaexaggera
4、tedExampleP(X³8)ExampleP(X³8)NormalDistributionStandardizedNormalDistribution.1179.5000.3821ShadedareaexaggeratedCentralLimitTheoremAssamplesizegetslargeenough(³30)...samplingdistributionbecomesalmostnormal.IntroductiontoEstimationStatisticalMethodsEstimationProcessMean,m,isunknown
5、PopulationRandomSampleIam95%confidentthatmisbetween40&60.Mean`X=50SampleJJJJJJJJJJJPopulationParametersAreEstimatedPointEstimationProvidessinglevalueBasedonobservationsfrom1sampleGivesnoinformationabouthowclosevalueistotheunknownpopulationparameterExample:Samplemean`X=3ispointestimateofun
6、knownpopulationmeanIntervalEstimationProvidesrangeofvaluesBasedonobservationsfrom1sampleGivesinformationaboutclosenesstounknownpopulationparameterStatedintermsofprobabilityExample:Unknownpopulationmeanliesbetween50&70with95%confidenceKeyElementsofIntervalEstimationConfidenceintervalSampl
7、estatistic(pointestimate)Confidencelimit(lower)Confidencelimit(upper)Aprobabilitythatthepopulationparameterfallssomewherewithintheinterval.ConfidenceLimitsforPopulationMeanParameter=Statistic±Error©1984-1994T/MakerCo.ManySamplesHaveSameInterval90%Samplessx_`Xm`X=
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