环境数据分析课件 (6).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.Histograms Showing Hypothetical Distributions With the Same Mean,Median,and Mode(10)but With Low Variability(Top)and High Variability(Bottom)02468100 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20FrequencyX024681012141618200 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20FrequencyXIn other words,dispersion helps to understand the distribution of the data.1.Range 2.Quartile Deviation 3.Average Deviation 4.Standard Deviation5.Coefficient of variation Soil health indexFrequency2432352210218205193183170163Range is the interval between the highest and the lowest score in the distribution,which is absolute range of values.Plot numberCoverage(%)N1100N294N392N492N598N695N795N898N993N1093N1194N1296N1398N1490N1594N1697N1799N1890N1997Plot numberCoverage(%)N1100N294N392N492N598N695N795N898N993N1093N1194N1296N1398N1490N1594N1697N1799N1890N1997N20304)1(niRoughly speaking,the standard deviation of a distribution is,the average distance between the numbers and the mean.XiDiscrepancy(Xi-mean)（Xi-mean)22-112-113005244111-24411300300Mean=3s=1.225s2=1.5212)(1niixN212)(11xxnsnii)(11xxnDxnii100%sVxCoefficient of variation
