Chapter 10.3, Problem 5E

A newly designed quality-control program for a certain process involves sampling 20 items each day and counting the number of defective items. The numbers of defectives in the first 10 samples are 0, 0, 1, 0, 1, 0, 0, 0, 1, 0. A member of the quality-control team asks for advice, expressing concern that the numbers of defectives are too small to construct an accurate p chart. Which of the following is the best advice?

1. i. Nothing needs to be changed. An accurate p chart can be constructed when the number of defective items is this small.
2. ii. Since the proportion of items that are defective is so small, it isn’t necessary to construct a p chart for this process.
3. iii. Increase the value of p to increase the number of defectives per sample.
4. iv. Increase the sample size to increase the number of defectives per sample.