Learning Outcomes

After completing this section, students should be able to do the following.

  • Be able to give examples of causes of variation.
  • Be able to discuss characteristics of an in-control and out-of-control process.
  • Be able to explain the use of X-bar and R control charts.
  • Be able to find the upper and lower control limits for an X-bar chart.
  • Be able to describe how the sample size affects control limits for an X-bar chart.
  • Be able to apply Nelson’s rules to X-bar charts to determine when a process is not in statistical control.

Prerequisites

It is assumed that students are familiar with the following concepts.

  • Sampling distribution
  • Central Limit Theorem
  • The Empirical Rule