Certified Production & Operations Manager (POM) Practice Exam

What does it imply if a control chart signals that a process is no longer in control?

1. The process needs no adjustments

2. There may be an assignable cause affecting the process

3. The quality of raw materials is poor

4. The employees are not performing well

The correct answer is: There may be an assignable cause affecting the process

When a control chart indicates that a process is no longer in control, it suggests that there are variations present that can be attributed to specific, identifiable factors rather than random chance alone. This situation implies the presence of an assignable cause affecting the process. Assignable causes are variations that can be traced back to specific issues that are not part of the inherent process variability, such as machine malfunctions, changes in raw materials, or human error. Identifying and investigating these assignable causes is essential for reinstating control within the process. It allows management to take corrective actions to eliminate the root causes of the variability, thereby improving process stability and consistency. While the other options may seem relevant, they are too specific or misinterpret the implications of the control chart signals. For instance, the idea that the process needs no adjustments contradicts the fact that a process signaled as out of control necessitates intervention. Similarly, attributing the lack of control to poor quality raw materials or employee performance overlooks the broader aspects of process variability, which could stem from various assignable causes. Thus, recognizing an assignable cause is pivotal in ensuring effective process management and quality control.