The market research department of a soft drink

manufacturer is investigating the effectiveness of a price discount

coupon on the purchase of a two-liter beverage product.

A sample of 5500 customers was given coupons for varying

price discounts between 5 and 25 cents. The response variable

was the number of coupons in each price discount category

redeemed after one month. The data follow in Table E11-15.

(a) Fit a logistic regression model to the data. Use a simple linear

regression model as the structure for the linear predictor.

(b) Is the logistic regression model in part (a) adequate?

(c) Draw a graph of the data and the fitted logistic regression model.

(d) Expand the linear predictor to include a quadratic term. Is

there any evidence that this quadratic term is required in the model?

(e) Draw a graph of this new model on the same plot that you prepared

in part (c). Does the expanded model visually provide a

better fit to the data than the original model from part (a)?