統(tǒng)計學-基于R第3版習題答案(第三章)

第3章 數(shù)據(jù)的描述統(tǒng)計習題3.1 1. 平均數(shù)、標準差、極差、四分位差 load(D:工作總結(jié)人大R語言統(tǒng)計學基于R（第3版）例題和習題數(shù)據(jù)（公開資源）exercisech3exercise3_1.RData) mean(exercise3_1$網(wǎng)購金額) 1 1032.64 median(exercise3_1$網(wǎng)購金額)1 985.5 sd(exercise3_1$網(wǎng)購金額)1 385.3728 R IQR(exercise3_1$網(wǎng)購金額,type=6) #四分位差，Q75%-Q25%1 422.752. 計算分位數(shù) quantile(exercise3_1$網(wǎng)購金額,probs=c(0.1,0.25,0.5,0.75,0.9),type=6) 10% 25% 50% 75% 90% 532.20 825.75 985.50 1248.50 1490.90 3. 計算標準分數(shù)，檢測離群點 as.vector(round(scale(exercise3_1$網(wǎng)購金額),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$網(wǎng)購金額,scale(exercise3_1$網(wǎng)購金額),scale(exercise3_1$網(wǎng)購金額)3)正負三個標準差 ,1 ,2 ,3。14, 2270 3.21081302 115, 513 -1.34840861 0。4. 計算偏度，峰度 library(agricolae) skewness(exercise3_1$網(wǎng)購金額) # 偏度，中等偏斜分布，右偏1 0.6633022 kurtosis(exercise3_1$網(wǎng)購金額) # 峰度，尖峰分布，比正態(tài)分布高1 1.220333.2產(chǎn)品數(shù)量的分布特點 load(D:工作總結(jié)人大R語言統(tǒng)計學基于R（第3版）例題和習題數(shù)據(jù)（公開資源）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，右偏數(shù)值比較集中右邊，離散程度最小 boxplot(exercise3_2)3.3 library(aplpack) stem.leaf.b