8.6. In Example 6.6, a 24 factorial design was used to improve the response rate to a credit card mail marketing offer. Suppose that the researchers had used the 24!1 fractional factorial design with I $ ABCD instead. Set up the design and select the responses for the runs from the full factorial data in Example 6.6. Analyze the data and draw conclusions.

Compare your findings with those from the full factorial in Example 6.6.