Chapter 2: Q.13-8OQ (page 340)
Question: A shirt manufacturer buys cloth by the 100-yard roll from a supplier. For setting up a control chart to manage the irregularities (e.g., loose threads and tears), the following data were collected from a sample provided by the supplier.
Sample | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
Irregularities | 3 | 5 | 2 | 6 | 5 | 4 | 6 | 3 | 4 | 5 |
a. Using these data, set up a c-chart with z = 2.
b. Suppose the next five rolls from the supplier had three, two, five, three, and seven irregularities. Is the supplier process under control?
Short Answer
Answer
Statistical quality control (SQC) could be some various techniques designed to evaluate quality from a conformance view; that's, how well are we doing at meeting the specifications that have been set during the planning of the parts or services that we are providing. Managing quality performance using SQC techniques usually involves the periodic sampling of a process and analysis of those data using statistically derived performance criteria.