Certified Production & Operations Manager Exam Practice 2026 – Complete Study Guide

When assignable variation is detected in a process, the appropriate action is to identify and investigate the cause. Assignable variation refers to variability in a process that can be attributed to a specific factor or event. Unlike common cause variation, which is inherent to the process and varies randomly, assignable variation indicates that something unusual is influencing the process performance.

Taking the time to identify and investigate the cause is crucial for several reasons. It enables the practitioner to understand whether the variation is due to a one-time event, a change in materials, equipment malfunction, human error, or any other identifiable source. By pinpointing the cause, steps can then be taken to correct the issue, thereby preventing similar variations from recurring in the future. This approach leads to improved process stability, enhanced quality, and more efficient operations.

In contrast, ignoring it as normal fluctuation would risk allowing significant issues to go unaddressed, potentially leading to larger problems down the line. Adjusting the process settings immediately may not resolve the underlying issue and could introduce new problems. Similarly, merely documenting the variation without investigation does not proactively address the cause and may overlook opportunities for process improvement. Prioritizing the analysis of assignable variation helps develop a culture of continuous improvement and operational excellence.