Basic Skills and Concepts

Monitoring Aspirin: The labels on a bottle of Bayer aspirin indicate that the tablets contain 325 mg of aspirin. Supposed manufacturing specifications require that tablets have between 315 mg and 335 mg of aspirin, so a tablet is considered to be a defect if the amount of aspirin is not within those limits. If the proportion of defects is monitored with a p chart and is found to be within statistical control, can we conclude that almost all of the tablets meet the manufacturing specifications? Why or why not?

Interpreting a Control Chart: Assume that the proportion of defective Bayer aspirin tablets is monitored with a control chart and we conclude that the process is not within statistical control because there is a downward pattern that is not random. Should the downward pattern be corrected? What should the company do?

1 What is process data?

2 What is the difference between random variation and assignable variation ?

Identify three specific criteria for determining when a process is out of statistical control.