Data<-read.table("liver_weights.txt")
x=Data[(Data$dosage==1),2]
y=Data[(Data$dosage==2),2]
boxplot(x,y)
t.test(x, y, alternative = "less", mu = 0, paired = FALSE, var.equal = TRUE,conf.level = 0.95)
z=c((x-mean(x))/sd(x),(y-mean(y))/sd(y))
qqnorm(z)
abline(a=0,b=1)