diff <- Stress$prestress - Stress$poststress
qqnorm(diff)
qqline(diff)
t.test(diff)
t.test(Stress$prestress, Stress$poststress, paired = TRUE)
if (FALSE) {
wilcox.test(Stress$prestress, Stress$poststress, paired = TRUE)
}
Run the code above in your browser using DataLab