a.-d. Answer the same questions as in parts (a) through (d) in Problem 1 regarding an analysis of covariance designed to control for both AGE and QUET. (AGE = 53.250.) Use the results from Problem 9 in Chapter 12.
e. Is it necessary to control for both AGE and QUET as opposed to controlling just one of the two covariates?
In Problem 1
a. State the appropriate ANACOVA regression model to use for comparing the mean blood pressures in the two smoking categories, controlling for QUET.
b. Determine the adjusted SBP means for smokers and nonsmokers. Compare these values to the unadjusted mean values
SBP(smokers) = 147.823 and SBP( nonsmokers) = 140.800
c. Test whether the true adjusted mean blood pressures in the two groups are equal. State the null hypothesis in terms of the regression coefficients in the ANACOVA model given in part (a).
d. Obtain a 95% confidence interval for the true difference in adjusted SBP means.