环境数据分析课件 (7).pdf

Chapter 2 Descriptive StatisticsData and features determine the upper limit of“analysis”learning Frequencies&Histograms Central Tendency Statistical Dispersion Shapes of DistributionChapter 2 Descriptive StatisticsFigure x Histogram showing the distribution of soil health index Unimodal DistributionBimodal DistributionUnimodal and Symmetrical3311()/1nkiiSxxsnSkewnessSk0Sk0Sk=0Unimodal and SymmetricalMean=Median=Mode=10Mean=4.1Median=3.5Mode=2Mean=245（ms）Mean=1445（ms）Median=250（ms）Median=250（ms）2002502802501802002202402602803001234reaction times(ms)2002502802505000010002000300040005000600012345reaction times(ms)2002502802505000010002000300040005000600012345reaction times(ms)1144()/31nuiKxxsinKurtosisLeptokurtic PlatykurticNormalHomeworkEvery variable has a distribution.The distribution can be described using a frequency table and histogram.It can also be described by skeweness and kurtosis.The central tendency-the mean,median,and mode.The variability,average deviation,standard deviation and coefficient of variance.