An experiment was performed to explore the effect of a marketing campaign on web site traffic. The data in webtraff .txt are the number of weeks into the marketing campaign and the web site traffic. The traffic measure is a daily average for two random 24-hour periods during the particular week. The day that the traffic was sampled was determined before the study began and only weekdays were considered. The values are in lOOO's of hits per day.

(a) Make a scatter plot of the data and suggest a suitable polynomial model.

(b) Fit the model you chose in part (a).

(c) What does the data at time zero represent? Why is this important?

(d) Predict the web site traffic for the third week of the study.

(e) Plot your fitted model on your scatter plot (you may need to do this by hand), and comment on the fit. How precise do you think your predictions will be?