CAPM Practice: Demonstrate an understanding of common problem-solving tools and techniques

A run of seven or more consecutive points on one side of the mean (some standards say eight or nine) is a signal of special cause variation, even if no points exceed the control limits. This non-random pattern suggests the process has shifted, and root cause investigation is warranted. Common-cause variation produces random scatter around the mean.

**Why not A:** Concluding that the data collection methodology is flawed without investigation is premature. A run of nine points above the mean is a recognized pattern indicating special cause variation, not necessarily a data quality issue. Investigation should determine the actual cause.

**Why not B:** Recalculating control limits is not the correct response to a detected pattern. Control limits are based on the process's natural variation and should not be adjusted to accommodate non-random patterns. The pattern signals an underlying process shift that needs investigation.

**Why not D:** The process is not in control. A run of seven or more consecutive points on one side of the mean is a well-established signal of special cause variation in statistical process control. This non-random pattern indicates the process has shifted and requires investigation.