determining sample size.ppt

ExploringMarketingResearchWilliamG.Zikmund,Chapter17:DeterminingSampleSize,天马行空官方博客：,Copyright2000byHarcourt,Inc.Allrightsreserved.,WhatdoesStatisticsMean?,DescriptiveStatisticsNumberofPeopleTrendsinEmploymentDataInferentialStatisticsMakeaninferenceaboutapopulationfromasample,PopulationParameterVersusSampleStatistics,Copyright2000byHarcourt,Inc.Allrightsreserved.,Copyright2000byHarcourt,Inc.Allrightsreserved.,PopulationParameter,VariablesinapopulationMeasuredcharacteristicsofapopulationGreeklower-caselettersasnotation,Copyright2000byHarcourt,Inc.Allrightsreserved.,SampleStatistics,VariablesinasampleMeasurescomputedfromdataEnglishlettersfornotation,Copyright2000byHarcourt,Inc.Allrightsreserved.,MakingDataUsable,FrequencyDistributionsProportionsCentralTendencyMeanMedianModeMeasuresofDispersion,Copyright2000byHarcourt,Inc.Allrightsreserved.,FrequencyDistributionofDeposits,Frequency(numberofpeoplemakingdepositsAmountineachrange),lessthan$3,000499$3,000-$4,999530$5,000-$9,999562$10,000-$14,999718$15,000ormore8113,120,Copyright2000byHarcourt,Inc.Allrightsreserved.,AmountPercent,lessthan$3,00016$3,000-$4,99917$5,000-$9,99918$10,000-$14,99923$15,000ormore26100,PercentageDistributionofAmountsofDeposits,Copyright2000byHarcourt,Inc.Allrightsreserved.,AmountProbability,lessthan$3,000.16$3,000-$4,999.17$5,000-$9,999.18$10,000-$14,999.23$15,000ormore.261.00,ProbabilityDistributionofAmountsofDeposits,Copyright2000byHarcourt,Inc.Allrightsreserved.,MeasuresofCentralTendency,Mean-ArithmeticAverage,population;,sampleMedian-MidpointoftheDistributionMode-theValuethatoccursmostoften,PopulationMean,Copyright2000byHarcourt,Inc.Allrightsreserved.,SampleMean,Copyright2000byHarcourt,Inc.Allrightsreserved.,Copyright2000byHarcourt,Inc.Allrightsreserved.,NumberofSalesCallsPerDaybySalespersons,NumberofSalespersonSalescalls,Mike4Patty3Billie2Bob5John3Frank3Chuck1Samantha526,Copyright2000byHarcourt,Inc.Allrightsreserved.,SalesforProductsAandB,BothAverage200,ProductAProductB,196150198160199176199181200192200200200201201202201213201224202240202261,Copyright2000byHarcourt,Inc.Allrightsreserved.,MeasuresofDispersion,TheRangeStandardDeviation,Copyright2000byHarcourt,Inc.Allrightsreserved.,MeasuresofDispersionorSpread,RangeMeanabsolutedeviationVarianceStandarddeviation,Copyright2000byHarcourt,Inc.Allrightsreserved.,TheRangeasaMeasureofSpread,Therangeisthedistancebetweenthesmallestandthelargestvalueintheset.Range=largestvaluesmallestvalue,Copyright2000byHarcourt,Inc.Allrightsreserved.,DeviationScores,Thedifferencesbetweeneachobservationvalueandthemean:,Copyright2000byHarcourt,Inc.Allrightsreserved.,LowDispersionVersesHighDispersion,150160170180190200210,54321,LowDispersion,ValueonVariable,Frequency,Copyright2000byHarcourt,Inc.Allrightsreserved.,150160170180190200210,54321,Frequency,Highdispersion,ValueonVariable,AverageDeviation,Copyright2000byHarcourt,Inc.Allrightsreserved.,MeanSquaredDeviation,Copyright2000byHarcourt,Inc.Allrightsreserved.,TheVariance,Copyright2000byHarcourt,Inc.Allrightsreserved.,Variance,Copyright2000byHarcourt,Inc.Allrightsreserved.,Copyright2000byHarcourt,Inc.Allrightsreserved.,ThevarianceisgiveninsquaredunitsThestandarddeviationisthesquarerootofvariance:,SampleStandardDeviation,Copyright2000byHarcourt,Inc.Allrightsreserved.,Copyright2000byHarcourt,Inc.Allrightsreserved.,TheNormalDistribution,NormalCurveBellShapedAlmostallofitsvaluesarewithinplusorminus3standarddeviationsI.Q.isanexample,Copyright2000byHarcourt,Inc.Allrightsreserved.,NormalDistribution,MEAN,Copyright2000byHarcourt,Inc.Allrightsreserved.,2.14%,13.59%,34.13%,34.13%,13.59%,NormalDistribution,2.14%,Copyright2000byHarcourt,Inc.Allrightsreserved.,NormalCurve:IQExample,85,115,100,145,70,Copyright2000byHarcourt,Inc.Allrightsreserved.,StandardizedNormalDistribution,SymetricalaboutitsmeanMeanidentifieshighestpointInfinitenumberofcases-acontinuousdistributionAreaundercurvehasaprobabilitydensity=1.0Meanofzero,standarddeviationof1,Copyright2000byHarcourt,Inc.Allrightsreserved.,StandardNormalCurve,Thecurveisbell-shapedorsymmetricalAbout68%oftheobservationswillfallwithin1standarddeviationofthemeanAbout95%oftheobservationswillfallwithinapproximately2(1.96)standarddeviationsofthemeanAlmostalloftheobservationswillfallwithin3standarddeviationsofthemean,Copyright2000byHarcourt,Inc.Allrightsreserved.,AStandardizedNormalCurve,0,1,-1,-2,2,z,Copyright2000byHarcourt,Inc.Allrightsreserved.,TheStandardizedNormalistheDistributionofZ,z,+z,StandardizedScores,Copyright2000byHarcourt,Inc.Allrightsreserved.,Copyright2000byHarcourt,Inc.Allrightsreserved.,StandardizedValues,Usedtocompareanindividualvaluetothepopulationmeaninunitsofthestandarddeviation,LinearTransformationofAnyNormalVariableintoaStandardizedNormalVariable,-2-1012,Sometimesthescaleisstretched,Sometimesthescaleisshrunk,m,m,s,s,X,Copyright2000byHarcourt,Inc.Allrightsreserved.,Copyright2000byHarcourt,Inc.Allrightsreserved.,PopulationDistributionSampleDistributionSamplingDistribution,Copyright2000byHarcourt,Inc.Allrightsreserved.,PopulationDistribution,m,x,s,-s,Copyright2000byHarcourt,Inc.Allrightsreserved.,SampleDistribution,_C,X,S,Copyright2000byHarcourt,Inc.Allrightsreserved.,SamplingDistribution,Copyright2000byHarcourt,Inc.Allrightsreserved.,StandardErroroftheMean,Standarddeviationofthesamplingdistribution,CENTRALLIMITTHEORM,Copyright2000byHarcourt,Inc.Allrightsreserved.,StandardErroroftheMean,Copyright2000byHarcourt,Inc.Allrightsreserved.,Copyright2000byHarcourt,Inc.Allrightsreserved.,Copyright2000byHarcourt,Inc.Allrightsreserved.,ParameterEstimates,PointEstimatesConfidenceintervalestimates,ConfidenceInterval,Copyright2000byHarcourt,Inc.Allrightsreserved.,Copyright2000byHarcourt,Inc.Allrightsreserved.,Copyright2000byHarcourt,Inc.Allrightsreserved.,Copyright2000byHarcourt,Inc.Allrightsreserved.,EstimatingtheStandardErroroftheMean,Copyright2000byHarcourt,Inc.Allrightsreserved.,Copyright2000byHarcourt,Inc.Allrightsreserved.,Copyright2000byHarcourt,Inc.Allrightsreserved.,RandomSamplingErrorandSampleSizeareRelated,Copyright2000byHarcourt,Inc.Allrightsreserved.,SampleSize,Variance(StandardDeviation)MagnitudeofErrorConfidenceLevel,SampleSizeFormula,Copyright2000byHarcourt,Inc.Allrightsreserved.,SampleSizeFormula,Copyright2000byHarcourt,Inc.Allrightsreserved.,SampleSizeFormula-example,Supposeasurveyresearcher,studyingexpendituresonlipstick,wishestohavea95percentconfidentlevel(Z)andarangeoferror(E)oflessthan$2.00.Theest