Exercise_0323_2

第二題 ＃先從網路抓取資料

theURL <-"http://www1.aucegypt.edu/faculty/hadi/RABE5/Data5/P005.txt"
dta<- read.table(file = theURL, header = T, sep = "\t")
head(dta) #看一下前六欄的資料

##          City COL   PD URate     Pop Taxes Income RTWL
## 1     Atlanta 169  414  13.6 1790128  5128   2961    1
## 2      Austin 143  239  11.0  396891  4303   1711    1
## 3 Bakersfield 339   43  23.7  349874  4166   2122    0
## 4   Baltimore 173  951  21.0 2147850  5001   4654    0
## 5 Baton Rouge  99  255  16.0  411725  3965   1620    1
## 6      Boston 363 1257  24.4 3914071  4928   5634    0

#把要比較的變項取出來
dta_compare <- dta[, c('Income', 'Taxes')]
round(cor(dta_compare), 3)#只取到小數點後第三位

##        Income Taxes
## Income  1.000 0.056
## Taxes   0.056 1.000

#另一種方法
round(cor(dta$Income, dta$Taxes),3)

## [1] 0.056

#可以進一步檢定相關是否顯著，以及信賴區間
cor.test(~ Income + Taxes, data = dta_compare)

## 
##  Pearson's product-moment correlation
## 
## data:  Income and Taxes
## t = 0.33696, df = 36, p-value = 0.7381
## alternative hypothesis: true correlation is not equal to 0
## 95 percent confidence interval:
##  -0.2684231  0.3691383
## sample estimates:
##       cor 
## 0.0560718