##### Example 10.6 ##### dat <- read.table(file = "http://www.stat.umn.edu/~wuxxx725/data/class.txt", header = TRUE) head(dat) # Sample of Male Haircuts MaleHair <- dat$Haircut[dat$Gender == "M"] # Sample of Female Haircuts FemaleHair <- dat$Haircut[dat$Gender == "F"] # Confidence Interval for the Mean Difference t.test(x = MaleHair, y = FemaleHair, alternative = "two.sided", conf.level = 0.95) # Two-Sample t-test t.test(x = MaleHair, y = FemaleHair, alternative = "less", conf.level = 0.95) ##### Example 10.3 ##### BAC.sl <- c(0.007, 0.010, 0.009, 0.011, 0.008, 0.006) BAC.ha <- c(0.013, 0.017, 0.015, 0.014, 0.010, 0.009) t.test(x = BAC.sl, y = BAC.ha, paired = TRUE, alternative = "less", conf.level = 0.95) # or equivalently: perform one sample t-test on the difference t.test(x = BAC.sl - BAC.ha, alternative = "less", conf.level = 0.95)