Weekly sales of a company’s product (y) and those of its main competitor (x) were recorded for one year.

a. Conduct a regression analysis of these data.

b. Plot the residuals versus the time periods. Does there appear to be autocorrelation?

c. Perform the Durbin-Watson test. Is there evidence of autocorrelation? Use α = .10.

d. If autocorrelation was detected in Part c, propose an alternative regression model to remedy the problem. Use the computer to generate the statistics associated with this model.

e. Redo Parts b and c. Compare the two models.