Consider the 25 design in Problem 6.24. Suppose that only a one-half fraction could be run. Furthermore, two days were required to take the 16 observations, and it was necessary to confound the 25-1 design in two blocks. Construct the design and analyze the data.
Problem 6.24:
A company markets its products by direct mail. An experiment was conducted to study the effects of three factors on the customer response rate for a particular product. The three factors are A = type of mail used (3rd class, 1st class), B = type of descriptive brochure (color, black-and-white), and C = offered price ($19.95, $24.95). The mailings are made to two groups of 8000 randomly selected customers, with 1000 customers in each group receiving each treatment combination. Each group of customers is considered as a replicate. The response variable is the number of orders placed. The experimental data are shown in Table P6.6.
(a) Analyze the data from this experiment. Which factors significantly affect the customer response rate?
(b) Analyze the residuals from this experiment. Are there any indications of model inadequacy?
(c) What would you recommend to the company?