Which statement below is TRUE about control chart patterns?

The statement that refers to 14 points alternating up or down is correct regarding control chart patterns. This pattern is known as a "oscillating" or "alternating" sequence, which can be indicative of a lack of control in a process. Identifying patterns like these is crucial for understanding process behavior.

In quality control, a control chart is used to monitor process variation over time. While the presence of points oscillating can indicate a potential issue, it is important to note that some patterns, such as sustained trends, may signal a need for investigation into the process. Control limits serve to help differentiate between common cause variation and special cause variation, which is significant in deciding whether a process is under control or if adjustments are needed.

The other statements do not accurately describe control chart patterns in this context. For instance, all points being within control limits does not necessarily imply the absence of patterns; the analysis focuses more on the arrangement of points than their strict adherence to the limits alone. Similarly, stating that all trends must exceed 10 points is misleading, as control charts can show trends regardless of the number of points. Lastly, the requirement for points to lie exactly on the average line contradicts the fundamental concept of variability, which is inherent