统计学-基于R第3版习题答案(第三章)

第3章 数据的描述统计习题3.1 1. 平均数、标准差、极差、四分位差 load(D:工作总结人大R语言统计学基于R（第3版）例题和习题数据（公开资源）exercisech3exercise3_1.RData) mean(exercise3_1$网购金额) 1 1032.64 median(exercise3_1$网购金额)1 985.5 sd(exercise3_1$网购金额)1 385.3728 R IQR(exercise3_1$网购金额,type=6) #四分位差，Q75%-Q25%1 422.752. 计算分位数 quantile(exercise3_1$网购金额,probs=c(0.1,0.25,0.5,0.75,0.9),type=6) 10% 25% 50% 75% 90% 532.20 825.75 985.50 1248.50 1490.90 3. 计算标准分数，检测离群点 as.vector(round(scale(exercise3_1$网购金额),4) 1 -0.0743 -0.2897 -0.2715 0.2993 0.9948 -1.1175 -0.1106 0.2656 -0.4039 0.9014 1.3165 0.7171 -0.6322 3.210815 -1.3484 -1.3251 -1.3095 -0.0380 -0.1963 1.0129 -0.4013 -0.5051 -0.3312 -0.4999 0.4966 -0.3027 1.1920 -0.253429 -1.1849 -1.9297 0.3461 -0.2715 -0.2430 0.2007 0.5562 0.0762 0.6912 -0.7879 -1.2005 -0.9747 -1.7869 0.193043 1.9964 0.5718 2.0327 0.4343 -0.1340 -1.0059 0.2604 1.1634 cbind(exercise3_1$网购金额,scale(exercise3_1$网购金额),scale(exercise3_1$网购金额)3)正负三个标准差 ,1 ,2 ,3。14, 2270 3.21081302 115, 513 -1.34840861 0。4. 计算偏度，峰度 library(agricolae) skewness(exercise3_1$网购金额) # 偏度，中等偏斜分布，右偏1 0.6633022 kurtosis(exercise3_1$网购金额) # 峰度，尖峰分布，比正态分布高1 1.220333.2产品数量的分布特点 load(D:工作总结人大R语言统计学基于R（第3版）例题和习题数据（公开资源）exercisech3exercise3_2.RData) library(psych) describe(exercise3_2) vars n mean sd median trimmed mad min max range skew kurtosis se方法A 1 15 165.60 2.13 165 165.54 1.48 162 170 8 0.28 -0.79 0.55方法B 2 15 128.73 1.75 129 128.77 1.48 125 132 7 -0.14 -0.44 0.45方法C 3 15 125.53 2.77 126 126.08 1.48 116 128 12 -2.62 6.36 0.72 library(pastecs) round(stat.desc(exercise3_2),4) 方法A 方法B 方法Cnbr.val 15.0000 15.0000 15.0000nbr.null 0.0000 0.0000 0.0000nbr.na 0.0000 0.0000 0.0000min 162.0000 125.0000 116.0000max 170.0000 132.0000 128.0000range 8.0000 7.0000 12.0000sum 2484.0000 1931.0000 1883.0000median 165.0000 129.0000 126.0000mean 165.6000 128.7333 125.5333SE.mean 0.5503 0.4522 0.7163CI.mean.0.95 1.1803 0.9698 1.5362var 4.5429 3.0667 7.6952std.dev 2.1314 1.7512 2.7740coef.var 0.0129 0.0136 0.0221方法A最好，均值最高，右偏数值比较集中右边，离散程度最小 boxplot(exercise3_2)3.3 library(aplpack) stem.leaf.b