Problem:
The satisfaction rate of customers is to be monitored with a P Chart. The company sells software on-line (i.e., 7 days per week) to an average of 28 customers per day and asks each customer a few questions after they purchase the software. A key question asks "Overall, are you satisfied with our web site." Historically, 29.3% of customers answer the questions and 77.8% of customers answer "yes" to this question. For the P Chart, would it be most appropriate to setup subgroups based on a daily frequency, a weekly frequency, a monthly frequency, a quarterly frequency, or an annual frequency? Justify your results from both management and statistical perspectives (show calculations).