Rによる心理統計再入門6：２つの平均値の差の検定と信頼限界

よく使われる２つの平均値の差の検定と、差の95％の信頼区間をもとめる例。


> x1<-c(3,4,5,6,7)
> x2<-c(0,1,2,3,4)
> t.test(x1,x2)

Welch Two Sample t-test

data: x1 and x2
t = 3, df = 8, p-value = 0.01707
alternative hypothesis: true difference in means is not equal to 0
95 percent confidence interval:
0.6939959 5.3060041
sample estimates:
mean of x mean of y
5 2

同様にデータに対応がある場合：
> x2<-c(1,1,2,3,4)
> x1<-c(3,4,5,6,6)
> t.test(x1,x2,paired=TRUE)

Paired t-test

data: x1 and x2
t = 10.6145, df = 4, p-value = 0.0004460
alternative hypothesis: true difference in means is not equal to 0
95 percent confidence interval:
1.919913 3.280087
sample estimates:
mean of the differences
2.6