p chart for a high-quality process. A manufacturer of consumer electronic equipment makes full use not only of statistical process control but also of automated testing equipment that efficiently tests all completed products. Data from the testing equipment show that finished products have only 3.5 defects per million opportunities.
(a) What is p‾ for the manufacturing process? If the process turns out 5000 pieces per day, how many defects do you expect to see per day? In a typical month of 24 working days, how many defects do you expect to see?
(b) What are the center line and control limits for a p chart for plotting daily defect proportions?
(c) Explain why a p chart is of no use at such high levels of quality.