26 Summary of Measures Range X – X Total Spread largestsmallestStandard DeviationXni21Dispersion about(Sample)Sample MeanStandard DeviationXNi2Dispersion about(Population)Population MeanVariance(XX)2Squared Dispersioni(Sample)n– 1about Sample Mean
34 The Coefficient of Variation Coefficient of Variation of a population:This can be used to compare two distributions directly to see which has more dispersion because it does not depend on units of the distribution.
36 Coefficient of Variation of Wealth = /= 1.749The standard deviation is 1.75% of the mean.
37 Sample statistics versus population parameters MeasurePopulation ParameterSample StatisticMeanVarianceStandard Deviation
38 Pitfalls in Numerical Descriptive Measures Data analysis is objectiveShould report the summary measures that best describe and communicate the important aspects of the data setData interpretation is subjectiveShould be done in fair, neutral and clear manner