Certified Production & Operations Manager (POM) Practice Exam

When measuring defects in a process, which control chart is most appropriate?

1. c-chart

2. p-chart

3. R-chart

4. x-bar chart

The correct answer is: c-chart

The c-chart is the most appropriate choice for measuring defects in a process, particularly when dealing with count data where the number of defects can vary. This chart is specifically designed to monitor the count of defects per unit of output, making it ideal for quality control situations where the focus is on the number of nonconformities found in a specific sample size. This chart is suited for situations where the opportunity for defects is constant, and it allows for the detection of process behavior over time. In applications such as manufacturing, using a c-chart helps organizations understand the stability of their processes and identify when the number of defects surpasses normal variation, signaling a need for corrective action. Other chart types may not be as suitable. For instance, the p-chart is used for proportions of defective items in a sample, rather than counting the total number of defects. The R-chart and x-bar chart focus on variations in sample means and ranges, which may not directly relate to defect counting. Therefore, in contexts specifically centered around measuring and managing defect counts, the c-chart stands out as the appropriate tool.