For the study discussed in the text that investigates the effect of carbon monoxide exposure on patients with coronary artery disease, baseline measures of pulmonary function were examined across medical centers. Another characteristic that you might wish to investigate is age. The relevant measurements are saved in a data set called cad. Indicators of center are saved under center.
a. Do you feel that it is appropriate to use ANOVA to evaluate these data? Explain.
b. For each medical center, what are the sample mean and standard deviation for the values of age?
c. What is the between-groups estimate of the variance?
d. What is the within-groups estimate of the variance?
e. Test the null hypothesis that at the time when the study was conducted, the mean ages for men at all three centers were identical. What do you conclude?