Refer to the previous exercise. We could instead use the Tukey method to construct multiple comparison confidence intervals. The Tukey confidence intervals having overall confidence level 95% have margins of error of 5.7, compared to 4.7 for the separate 95% confidence intervals in the previous exercise.
a. According to this method, which groups are significantly different?
b. Why are the margins of error larger than with the separate 95% intervals?