You used sales and number of orders to predict distribution costs at a mail-order catalog business.
a. Plot the residuals versus i.
b. Plot the residuals versus X1i.
c. Plot the residuals versus X2(.
d. Plot the residuals versus time.
e. In the residual plots created in (a) through (d), is there any evidence of a violation of the regression assumptions? Explain.
f. Determine the Durbin-Watson statistic.
g. At the 0.05 level of significance, is there evidence of positive autocorrelation in the residuals?
For Information: Problem 14.4