What type of changes are made only when points on the control chart are outside acceptable ranges?

The selection of process changes as the correct answer is justified by the fundamental principles of control charts and the Six Sigma methodology. Control charts are tools used to monitor the stability of processes over time. They help identify variations and determine whether those variations are due to common causes (inherent to the process) or special causes (indicating something has changed).

When points on a control chart fall outside the established control limits, it signals that the process may be experiencing special cause variation. This typically prompts process changes to address the underlying issues causing the deviations from the expected performance. The goal of making process changes in response to these outlier points is to restore the process to a state of control, ensuring it operates within the acceptable ranges once again.

The other types of changes mentioned, including scheduling, management, and personnel changes, typically do not directly address variations highlighted by control charts. While they could play a role in broader organizational improvements, they don’t specifically target the root causes of outlier points in the context of process stability as effectively as process changes do.